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Anesthesia: Essays and Researches
Review Article
Epilepsy and nonepilepsy surgery: Recent advancements in anesthesia management Sukhminder Jit Singh Bajwa, Ravi Jindal1 Departments of Anaesthesiology and Intensive Care, Gian Sagar Medical College and Hospital, Ram Nagar, Banur, Patiala, Punjab, 1 Amar Hospital, Patiala, India Correspondnce author: Dr. Sukhminder Jit Singh Bajwa, Department of Anaesthesiology and Intensive Care, Gian Sagar Medical College and Hospital, Ram Nagar, Banur, Punjab, House No‑27‑A, Ratan Nagar, Tripuri, Patiala, Punjab, India. E‑mail: [email protected]
Abstract Epilepsy is one of the most common encountered neurological disorders. Surgical procedures in epileptic patient throw numerous challenges to the attending anesthesiologist during the perioperative period. Various anesthetic drug interactions with antiepileptics, intraoperative and postoperative seizures management and management of status epilepticus are few considerations which an anesthesiologist can confront both during emergency or elective surgery. The role of anesthesiologist acquires significant dimensions in management of epilepsy ranging from operative procedure, status epilepticus to the intensive care management of such patients. It requires a skilful and clinically precise handling of such patients during pre‑op, peri‑op and post‑op period. Majority of times these patients present with co‑morbidities which makes the prophylactic management of epilepsy extremely difficult during surgical procedures. The responsibilities of anesthesiologist involve management of epileptic patients not only during epilepsy and nonepilepsy surgery but for other diagnostic and therapeutic procedures as well where sedation or anesthesia services are required. Postoperative management of such patients include careful observation for any seizures and/or pseudo‑seizures so as to manage appropriately. The knowledge regarding various antiepileptic agents and their potential side effects and interactions with anesthetic agents are of prime concern during surgical procedures for epilepsy and nonepileptic surgeries. The present article discusses the various anesthetic implications and considerations during management of such patients for epilepsy and nonepilepsy surgery. Key words: Anesthesia, epilepsy, pseudo‑seizures, seizures, status epilepticus
Introduction Epilepsy is the second most common neurological disorder, after stroke. The age‑adjusted incidence in developed countries is 24‑53 per 1,00, 000 person years. The incidence Access this article online Website
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is higher in males and in lower socioeconomic class. In India the overall prevalence rate of epilepsy is 5.59 per 1000 population.[1‑3] Management of an epileptic patient is a huge challenge for the attending anesthesiologist during the perioperative period. Various drug interactions of anesthetics with antiepileptics, intraoperative and postoperative seizures management and management of status epilepticus are few considerations which an anesthesiologist can confront both during emergency or elective surgery.
Classification of epileptic seizures
Epileptic seizures can be classified as partial, generalized, pseudoseizures, nonepileptic seizures and status epilepticus[4-6] [Table 1]. 10
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Bajwa and Jindal: Anesthesia in patient with epilepsy
Table 1: Showing the classification pattern of various seizure disorders Partial seizures
Generalized seizures
Simple Complex Partial onset with generalization
Inhibitory Absence: Typical and atypical Atonic Excitatory Myoclonic Clonic Tonic Tonic–clonic
Pseudoseizures
Causes of epilepsy
It is extremely difficult to ascertain the exact cause of epilepsy and only in 25‑35% of the patients, one can possibly be sure of the exact aetiology.[5,6] Following are few of the known causes of epilepsy: a. Genetic: Juvenile myoclonic epilepsy, benign rolandic epilepsy. b. Trauma: Depressed skull fractures or evidence of intracranial hemorrhage. c. Tumor: Epilepsy is more common with slow‑growing tumors, anterior hemisphere tumors and may be generalized or focal in nature. d. Infection: Bacterial, fungal or tuberculous meningitis and viral encephalitis. e. Cerebral degeneration: Alzheimer’s disease and multi‑infarct dementia. f. Cerebrovascular disease: Cerebral infarction or hemorrhage. g. Multiple sclerosis. h. Alcohol: Lowers seizure threshold. Seizures may occur with binge drinking or withdrawal. i. Metabolic disorders: Hypocalcemia, hyper‑calcemia, hypomagnesemia, hypoglycemia, hyponatremia and hypernatremia. Hepatic and renal failure can also precipitate seizures. In the developed countries predominant causes include developmental disorders and idiopathic causes in children and vascular and degenerative causes in adults, in the developing nations infections, parasites and trauma are the leading causes.[4]
Differential diagnosis
It is extremely essential to diagnose a case of epilepsy for an appropriate and timely therapeutic management. The diseases which are important for differential diagnosis of epilepsy includes syncope, transient ischemic attack, migraine, hyperventilation, narcolepsy, cataplexy, and nonepileptic seizures.[5]
Responsibilities of anesthesiologist in managing an epileptic patient Managing a surgical epileptic patient is a huge challenging task for the attending anesthesiologist and requires a lot of skilful and knowledgeable measures on his part to evaluate
Nonepileptic seizures
Status epilepticus
completely and conduct safe anesthetic procedure.[7] The role of the anesthesiologist in case of epileptic patient acquires important dimensions which includes, 1. Management of status epilepticus in the intensive care. 2. Perioperative management for epilepsy surgery. 3. Perioperative management for nonepilepsy surgery. 4. Management of postoperative seizures in previously normal patient. 5. Management of associated comorbid diseases.
Status epilepticus
Status epilepticus is one of the most dreaded medical emergencies which an anesthesiologist can encounter during emergency or elective surgery in a case of known epileptic patient. Status epilepticus can be defined as a continuous seizure activity lasting >30 min or intermittent seizure activity lasting >30 min during which consciousness is not regained.[1] Status epilepticus should be managed as early as possible, preferably within 30 minutes.[1]
Management of status epilepticus
The diagnosis of status epilepticus is basically made on clinical grounds and the symptomatology is characterized by tonic‑clonic seizures, loss of consciousness, tongue biting, urinary incontinence.[1,8-11] The management of status epilepticus should be initiated as early as possible and includes the following definite measures. • ABC (Airway, breathing and circulation). Primary resuscitative measures to manage an attack of epilepsy are extremely important as these patients are at high risk of injury, airway compromise and other potential serious complications. These primary measures involves. • Airway management. • Administering 100% oxygen. • Securing an IV access. • Sending venous blood sample for biochemical analysis (including RBS). • Closely monitoring the vital signs, ECG and SpO2. • Start IV infusion with normal saline. If hypoglycemia suspected or documented, give glucose. (adults: 100 mg thiamine IV followed by 50 ml of 50% glucose, children: 2 ml/kg of 25% glucose). 11
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• First line therapy: IV Benzodiazipines – Lorazepam (0.1 mg/kg max 2 mg/kg upto 4 mg total dose) or Diazepam (0.1 mg/kg max 5 mg/kg upto 20 mg total dose). • Second line therapy: IV Phenytoin (20 mg/kg max rate adults: 50 mg/min, children: 1 mg/kg/min) or Fosphenytoin (20 mg/kg Phenytoin equivalent (PE) @ 150 mg/min). • If seizures persist: Additional phenytoin (5‑10 mg/kg) or fosphenytoin (5‑10 mg/kg PE). • If seizures still persist: Phenobarbital 20 mg/kg (max @ 60 mg/min). • Intubation and ventilation to maintain normal PaO2 and PaCO2. • Fluid resuscitation should be continued. • If seizures remain uncontrolled propofol or thiopentone infusion. Taper infusions at 12 hours to observe further seizure activity.
Pharmacological therapy and possible drug interactions with anesthetics
Management of an epileptic patient, whether in operative suite or in intensive care unit always involve dedicated team efforts. However, the various drugs used to control epilepsy are not absolutely free from side effects and have their own complications. The current knowledge of potential interactions between anesthetic drugs and antiepileptic agents is limited to few percentage of medical fraternity. Table 2 gives an elaborative review of the antiepileptic medications and their possible interactions with other drugs during the perioperative period.[4,12-14]
Anesthetic management for epilepsy surgery
Surgical management may be indicated for cases with refractory epilepsy. It may be done to resect an epileptogenic focus or to interrupt a seizure pathway and includes[1] i. Temporal lobectomy. ii. Amygdalohippocampectomy. iii. Extratemporal cortical excision. iv. Hemispherectomy. v. Corpus callosotomy. vi. Vagal stimulation. vii. Electrical stimulation of centromedian thalamic nucleus.
Anesthetic considerations
Anesthesia for epilepsy surgery may be required either in the form of general anesthesia or local anesthesia supplemented with sedation. The possible roles of an anesthesiologist during epilepsy surgery include:[15] 1. Monitored anesthesia care during awake craniotomy. 2. Inducing intraoperative seizures for intraoperative electrocorticograhy. 3. Brain protection, maintenance of intracranial hemodynamics and preventing rise in intracranial pressure. 12
Bajwa and Jindal: Anesthesia in patient with epilepsy
4. Rapid postoperative recovery to provide for early neurological assessment. 5. Management of refractory seizures. Besides the possible role in epilepsy surgery, the responsibilities of anesthesiologist also extend to the preoperative period. During the diagnostic interventions preoperatively the role of anesthesiologists includes[1] 1. Providing monitored anesthesia care for radiological procedures like magnetic resonance imaging and positron emission tomography. 2. Monitored anesthesia care for stereotactic electrode insertion. 3. General anesthesia for epidural electrode and grid placement. 4. Thiopentone test for localisation of seizure focus. With gradual increase in thiopentone blood levels, β‑activity occurs in normal neural tissue on electroencephalography while seizure focus shows abnormal response. 5. Wada test is used to determine dominant cerebral hemisphere using amobarbital injected into carotid artery (to lateralize cerebral speech dominance).
Anesthetic management
Anesthetic management of patients with epilepsy involves numerous considerations preoperatively, perioperatively and during the postoperative period.
Preanesthetic evaluation
In addition to routine preanesthetic evaluation, one should assess for differential diagnosis of associated seizure disorders which can be attributed to various disease states such as Huntington’s chorea, tuberous sclerosis, neurofibromatosis, lesch nyhan sundrome.[1] Similarly, possible anesthetic and antiepileptic drug interactions should be considered as hepatic enzyme induction can lead to requirement of higher doses of nondepolarizing muscle relaxants and opioids. The clinical history and examination should also include for the possible presence of various side effects of ongoing epileptics such as gingival hypertrophy, megaloblastic anemia and so on.
Premedication
Premedicate with benzodiazepine, atropine or glycopyrrolate (as patients head and neck are inaccessible during intra‑op period) and continue with anticonvulsants on the morning of surgery.[1]
Monitoring
Intraoperative monitoring includes electrocardiography, noninvasive blood pressure, pulse oximetery, end tidal carbon dioxide, temperature and urine output. Central venous pressure monitoring may be required if significant blood loss is anticipated.[1,15,16]
Awake craniotomy
It is performed when epileptogenic focus is close to eloquent areas of the brain,[1] usually temporal
Mech of action
Modulating postsynaptic inhibitory action of γ‑aminobutyric acid (GABA) and blocking postsynaptic excitation by glutamate
Inhibitor of enzyme systems that inactivate GABA
Decreases sodium ion current, enhances effect of GABA, blocks N‑methyl‑D‑aspartate (NMDA) receptors
Blocks votage dependant sodium channels
Changes ionic conductance of sodium channels with membrane stabilising effect
Designed to prevent formation of epoxide metabolite of carbazepine
Stabilizing voltage sensitive sodium channels
Inhibits votage sensitive sodium current and facilitates GABA action
Metabolized to phenobarbital and other active metabolite
Facilitaes GABAergic action
Blocks non‑NMDA glutamate receptors and sodium channels, potentiates GABA action
Drug
Phenobarbital
Valproic acid
Felbamate
Phenytoin
Carbamazepine
Oxcarbazepine
Lamotrigine
Gabapentine
Primidone
Clonazepam
Topiramate
Partial seizures, tonic clonic seizures, lennox gastaut syndrome
Myoclonic seizures
Partial and generalized partial seizures, pain syndromes like erythromelalgia, reflex sympathetic dystrophy and neuropathic pain
Adult partial and generalised epilepsy, lennox gastaut syndrome
Convulsive and nonconvulsive partial epilepsy, trigeminal and glossopharyngeal neuralgia, bipolar disorder and alchohol withdrawl syndrome
Partial and generalised epilepsy
Isolated partial epilepsy, secondary generalise epilepsy, lennox gastaut sundrome
All types of epilepsy
For all types of epilepsy except primary generalized nonconvulsive type
Uses
Dizziness, nervousness, cognitive disturbances, ataxia, depression, diarrhea, glaucoma, loss of appetite and weight loss, paresthesias and urolithiasis, metabolic acidosis
Personality changes manifested as behavioral disorders, hyperactivity, irritability and difficulty concentrating, especially in children. Depression in the elderly. Sialorrhea and increased bronchial secretion
Fatigue, depression, psychosis, decreased libido, skin changes, leukopenia, thrombocytopenia and SLE
Sedation, diplopia, dizziness, ataxia, skin changes, weight gain, nausea and leucopenia
Dizziness, diplopia, tremor, insomnia, aggression, ataxia, allergic dermatitis, Stevens‑Johnson syndrome, headache, nausea, vomiting and blood dyscrasias
Sedation, dizziness, headache, amnesia, ataxia, diplopia, depression, insomnia, anxiety, nausea and vomiting, diarrhoea, hyponatremia, acne, alopecia and urticaria
Sedation, diplopia, dizziness, neutropenia, nausea, drowsiness, diarrhea, jaundice, oliguria, hypertension, cardiac arrhythmias, hyponatremia, agranulocytosis, aplastic anemia, allergic dermatitis, Stevens‑Johnson syndrome and systemic lupus erythematosus
nystagmus, diplopia, dizziness (vestibular cerebellar dysfunction), ataxia, nausea and vomiting, gingival hyperplasia, depression, megaloblastic anemia, drowsiness, agranulocytosis, aplastic anemia, allergic dermatitis, Stevens‑Johnson syndrome, hyperglycemia, hepatotoxicity, pancreatitis, acne, rough skin, hirsutism, teratogenicity and Dupuytren’s contracture
Insomnia, anorexia, nausea, headache, irritability, aplastic anemia and hepatotoxic effects
Tremors, weight gain, dyspepsia, nausea and vomiting, anorexia, alopecia, edema, encephalopathy (due to increased levels of ammonia), teratogenicity, agranulocytosis, aplastic anemia, allergic dermatitis, Stevens‑Johnson syndrome, hepatotoxicity, platelet changes that can lead to bleeding, and pancreatitis
Sedation, depression, hyperactivity (in children), confusion (in elderly), skin changes, megaloblastic anemia, osteomalacia, nystagmus, ataxia, abnormal collagen deposition (Dupuytren’s contracture), attacks of porphyria
Side effects
Table 2: Showing the indications, side effects and clinical actions/significance of various anti‑epileptic drugs
Contd...
Chronic use induces metabolism of enflurane, halothane and isoflurane
Induces hepatic microsomal system
Enhances hepatic oxidation and conjugation of liposomal drugs
Induces oxidative metabolism of liposomal drugs including thiopentone, propofol, midazolam, opiods and nondepolarising neuromuscular blockers
When used with other anticonvulsants its dose should be reduced by 20‑30%
Displaces diazepam from the binding site, hepatic microsomal enzyme inhibitor
Hepatic microsomal enzyme induction
Interaction
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Bajwa and Jindal: Anesthesia in patient with epilepsy
13
Irritability, Cushing syndrome, electrolyte disturbances (hypokalemia), impaired glucose tolerance, dilation of cerebral ventricles, increased cerebrospinal fluid, hypertension, cardiomyopathy, and sepsis
Sedation, asthenia, diplopia, hypohidrosis, skin changes, StevensJohnson syndrome, dizziness, headache, ataxia, anorexia, agitation, irritability, and nephrolithiasis, metabolic acidosis
Numerous drugs used in anesthesia have potential drug interactions with anti-epileptic agents which can be highly detrimental during surgical procedures.[1,4,7,15]
Benzodiazepines
It is also used as first‑line anticonvulsant drugs besides sedation purpose.
Propofol
West syndrome
Blocking voltage dependent sodium channels and T‑type calcium channels,
Cholinergic and serotonergic modulation
Zonisamide
ACTH and corticosteroids
Partial seizures
At ususal doses it is epileptogenic and thus should be avoided.
Uses
Etomidate
Blockage of GABA reuptake
its antiepileptic activity is related to inhibition of pre and postsynaptic chloride channels mediated by GABA. It is used for sedation, induction and maintenance of general anesthesia. It can cause abnormal movements as opisthotonus and myoclonia in normal as well as epileptic patients.
Tiagabine
Partial, secondarily generalised, generalised tonic clonic, myoclonic seizures, lennox gastaut syndrome
Dizziness, asthenia, somnolence, anxiety, nausea, nervousness, tremors, abdominal pain and cognitive disorders
Anesthetic drugs and epilepsy
Binds to protein A2 related to release of glutamate
Partial seizures, tonic clonic seizures
For other surgeries where general anesthesia is used, induction may be done with thiopentone or propofol. Maintenance is done using nitrous oxide, narcotic and sub‑MAC concentrations of isoflurane or sevoflurane. Early awakening allows rapid neurological assessment. Postoperatively pain relief is important. Blood levels of antiepileptics should be obtained to adjust the doses accordingly.
Levetiracetam
Drowsiness, weakness, dizziness, ataxia, amnesia, depression, anxiety, anorexia, diarrhea, dyspepsia, skin changes and pancytopenia
lobe epilepsy. Electrocorticography (ECoG) may be used to identify the epileptogenic focus. However, anesthetics have a depressant effect on ECoG. Neurolept anesthesia (combination of droperidol and fentanyl) was traditionally used for management of anesthesia. However, the side effects include postoperative extrapyramidal excitation, unconsciousness, restlessness and confusion. Propofol is now the preferred agent. Alfentanil, remifentanil or fentanyl are used for intraoperative analgesia. Field block is used to provide local anesthesia.
Mech of action
Table 2: Contd... 14
Bajwa and Jindal: Anesthesia in patient with epilepsy
Drug
Side effects
Interaction
Anesthesia: Essays and Researches; 7(1); Jan-Apr 2013
It is anticonvulsant at high doses and proconvulsant at clinical doses.
Ketamine
Droperidol
It has no proconvulsant activity.
Dexmeditomidine
It has no pro or anticonvulsant activity. Sedation due to dexmeditomidine shows EEG pattern similar to stage II sleep. It is used in autistic children for EEG recording. However, this drug has numerous beneficial effects when used through different routes. It prolongs analgesia of local anesthetics when used in neuraxial blocks, attenuates pressor response when used before induction of anesthesia, reduces requirement of postoperative analgesics and causes reduction of shivering postoperatively after general anesthesia.[17‑19]
Anesthesia: Essays and Researches; 7(1); Jan-Apr 2013
Bajwa and Jindal: Anesthesia in patient with epilepsy
Clonidine
It has been used in autistic patients for sedation during EEG recording. Its role is similar to dexmedetomidine when used through all the above mentioned routes but has lesser affinity at α‑2 receptors as compared to dexmedetomidine.[17,20,21] All barbiturates, except methohexitol, have significant anticonvulsant activity.
Opioids
Mepiridine, due to its metabolite normeperidine, has proconvulsant activity. In patients with renal failure, advanced malignancy, sickle cell disease, prolonged use, enzymatic induction with anticonvulsants, normeperidine gets accumulated and can lead to seizures. Morphine, though devoid of anticonvulsant activity, can cause tonic clonic activity when used in epidural space. High doses of phenylpiperidine derivatives (fentanyl, alfentanil, sufenanil and remifentanil) should be avoided in epileptic patients.
Nitrous oxide
Its epileptogenic potential is very low and can be safely used in epileptic patients.
Halothane
Has a potent anticonvulsant activity. Can cause epileptiform EEG and contraindicated in epileptic patients.
seizures,
is
Isoflurane
Has potent anticonvulsant activity.
Sevoflurane
Avoid use at concentration above 1.5 MAC and in presence of hypocapnia.
Desflurane
Has no proconvulsant activity.
Neuromuscular blockers
No reported proconvulsant activity.
Anticholinergics
Atropine, scopolamine and glycopyrrolate can be used in epileptics.
Local anesthetics
Barbiturates
Enflurane
Anticholinesterases
a. Nondepolarizing blockers: Phenytoin and carbamazepine used chronically increases hepatic clearance of rocuronium, pancuronium, vecuronium, cisatracurium, decreasing their duration of action. Atracurium and mivacurium are not metabolised by hepatic enzymes and hence their duration if action is not affected. Acute administration of phenytoin potentiates the neuromuscular blockade of rocuronium. Though laudanosine, an atracurium metabolite has been postulated to be proconvulsant, yet there is no report of such episode in human beings. b. Depolarizing blocker succinylcholine: Its duration of action is slightly increased.
At subtoxic doses they are anticonvulsants, sedatives and analgesics while at higher concentrations can cause seizure activity.
Antiemetics
Are of five main classes; dopamine antagonists, anticholinergics, antihistaminics, 5‑HT3 anatgonists, steroids. Dopamine antagonists (phenothiazines‑prochlorperazine, butyrophenones‑droperidol, benzamides‑metoclopramide) can cause extrapyramidal effects and dystonia which can be confused with epileptic activity.
Anesthetic management for nonepilepsy surgery
• Preoperatively a careful review of medical history, factors triggering seizures (fasting, stress, sleep deprivation, alcohol, and drugs), comorbidities, mental retardation, hypotonia, risk factors for aspiration and difficult airway should be assessed.[4,7,15] Evaluation by a neurologist preoperatively is preferable. Anticonvulsants should be continued as scheduled on the day of surgery. Midazolam is usually used for premedication. However, some anticonvulsants and ketogenic diet can lead to sedation. • Intraoperative monitoring depends upon the surgical procedure and the patients clinical condition. • For induction propofol or thiopentone may be used. Ketamine and etomidate are best avoided. Opioids other than meperidine may be used. Total intravenous anesthesia (TIVA) with propofol and fentanyl can also be used safely in such patients. [Ref] Neuraxial opioids can also be safely used. • Avoid intraoperative hypoxia, hypotension, hypocapnia and hyponatremia. • Regional anesthesia can be safely used. Coagulation profile, however, should be assessed because of propensity of certain anticonvulsants to precipitate coagulation disturbances. • Postoperatively anticonvulsants should be started as early as possible. If fasting time is 12‑14 hours, parenteral replacement for oral drugs may not be required. However, where fasting time exceeds 24 hours parenteral replacement is necessary.
Seizures occurring as a complication of anesthesia
Postoperative seizures, though rare, are a recognized complication of anesthetics.[4,7,15] Patients at risk are generally those who already have epilepsy, especially those with poor preoperative control and those undergoing brain surgeries. Rarely seizures can occur as isolated 15
Anesthesia: Essays and Researches; 7(1); Jan-Apr 2013
event in previously normal patient. This should prompt search for structural or chemical brain abnormality.
Risk factors for seizures postperatively
Vigil has to be exercised during post-operative period as numerous risk factors listed below can be potential cause of seizures.[22] 1. Pre‑existing epilepsy or seizure disorder, especially if poorly controlled. 2. Lengthy surgery or surgery that lasts longer than the effectiveness of the last dose of seizure medication in epileptics. 3. Pre‑existing brain abnormality such as tumor, aneurysm or scarring. 4. Alcoholism and alcohol withdrawal. 5. Illicit drug use. 6. Local anesthesia in large doses. 7. Certain anesthetics in combination with any of the above. 8. Chemical or electrolyte abnormality. Perioperative seizures, if prolonged, can cause brain damage due to hypoxia, apnea, prolonged postoperative mechanical ventilation, and delayed awakening from anesthesia. Physiological cardiac and respiratory regulation may be impaired. There may be tachycardia and tachypnea, apnea and bradycardia or sudden death due to autonomic instability, which causes cardiac arrhythmias or neurogenic pulmonary edema.[4]
Bajwa and Jindal: Anesthesia in patient with epilepsy
dystonic movements or epileptiform activity, but drug‑induced seizures are rare. Postoperative seizures are more common after neurosurgery. Pseudo‑epileptic seizures in the postoperative period resemble tonic–clonic seizures but are not associated with abnormal electrical discharges in the brain.[22] They tend to be associated with a history of convulsions and/or psychosomatic illness. They are characteristically flamboyant, last longer than 90 s and are associated with asynchronous limb movements, side‑to‑side head movements, closed eyes (including a resistanxce to eye opening) and maintenance of papillary reflexes. There is no cyanosis or postictal period but there may be incontinence or tongue‑biting. Seizures may settle with reassurance. Plasma prolactin concentrations tend to be raised after epileptic seizures and normal after pseudo‑seizures. However, the diagnosis of pseudo‑seizures remains primarily clinical. It is possible for both epileptic and pseudo‑epileptic seizures to coexist.
References 1. 2. 3. 4.
Management includes maintaining a patent airway with adequate ventilation and protect the patient from injuries resulting from seizures. Monitoring should be performed using cardioscope, blood pressure and pulse oximetry.[4]
5.
Should convulsions persist for more than 5 minutes, intravenous benzodiazepine should be used. Preffered drug is lorazepam. Alternatively diazepam (5‑20 mg) may be used. If convulsions persist, a second dose of benzodiazepine with phenytoin (20 mg/kg over 30 minutes) may be used. For refractory seizures, phenobarbital (1.5 mg/kg/min or 100 mg/70 kg/min can be used with a maximum dose of 20 mg/kg or 1,000 mg/70 kg), midazolam (0.1‑0.3 mg/kg in 2‑5 minutes, followed by infusion of 0.05 to 0.4 mg/kg/hour), propofol (1‑2 mg/kg followed infusion of 2‑10 mg/kg/h), thiopental (5‑10 mg/kg in 10 minutes, followed by infusion of 100‑400 mg/h), lidocaine (1.5‑2 mg/kg in 2‑5 minutes, followed by infusion of 2‑3 mg/kg/h for 12 hours), isoflurane (0.5‑1.5%) and ketamine (50‑100 mg followed by infusion of 50‑100 mg/h).[4]
7.
Postoperative pseudo‑epileptic seizures
Postoperative shivering is common complication of anesthesia. Various drugs and adjuvants have been successfully used during peri‑op period for the prevention of postoperative shivering.[19] It can be confused with epileptic seizures. Some anesthetic drugs can cause 16
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Anesthesia: Essays and Researches; 7(1); Jan-Apr 2013 18. Bajwa SS, Kaur J, Singh A, Parmar SS, Singh G, Kulshrestha A, et al.Attenuation of pressor response and dose sparing of opioids and anaesthetics with pre‑operative dexmedetomidine. Indian J Anaesth 2012;56:123‑8. 19. Bajwa SJ, Gupta S, Kaur J, Singh A, Parmar SS. Reduction in the incidence of shivering with perioperative dexmedetomidine: A randomized prospective study. J Anaesthesiol Clin Pharmacol 2012;28:86‑91. 20. Bajwa SJ, Kaur J, Bajwa SK, Bakshi G, Singh K, Panda A. Caudal ropivacaine‑clonidine: A better post‑operative analgesic approach. Indian J Anaesth 2010;54:226‑30. 21. Bajwa SJ, Bajwa SK, Kaur J, Singh A, Singh A, Parmar SS. Prevention of hypotension and prolongation of postoperative analgesia in emergency
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How to cite this article: Bajwa SJ, Jindal R. Epilepsy and nonepilepsy surgery: Recent advancements in anesthesia management. Anesth Essays Res 2013;7:10-7. Source of Support: Nil, Conflict of Interest: None declared.
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Anesthesia: Essays and Researches
Review Article
Epilepsy and nonepilepsy surgery: Recent advancements in anesthesia management Sukhminder Jit Singh Bajwa, Ravi Jindal1 Departments of Anaesthesiology and Intensive Care, Gian Sagar Medical College and Hospital, Ram Nagar, Banur, Patiala, Punjab, 1 Amar Hospital, Patiala, India Correspondnce author: Dr. Sukhminder Jit Singh Bajwa, Department of Anaesthesiology and Intensive Care, Gian Sagar Medical College and Hospital, Ram Nagar, Banur, Punjab, House No‑27‑A, Ratan Nagar, Tripuri, Patiala, Punjab, India. E‑mail: [email protected]
Abstract Epilepsy is one of the most common encountered neurological disorders. Surgical procedures in epileptic patient throw numerous challenges to the attending anesthesiologist during the perioperative period. Various anesthetic drug interactions with antiepileptics, intraoperative and postoperative seizures management and management of status epilepticus are few considerations which an anesthesiologist can confront both during emergency or elective surgery. The role of anesthesiologist acquires significant dimensions in management of epilepsy ranging from operative procedure, status epilepticus to the intensive care management of such patients. It requires a skilful and clinically precise handling of such patients during pre‑op, peri‑op and post‑op period. Majority of times these patients present with co‑morbidities which makes the prophylactic management of epilepsy extremely difficult during surgical procedures. The responsibilities of anesthesiologist involve management of epileptic patients not only during epilepsy and nonepilepsy surgery but for other diagnostic and therapeutic procedures as well where sedation or anesthesia services are required. Postoperative management of such patients include careful observation for any seizures and/or pseudo‑seizures so as to manage appropriately. The knowledge regarding various antiepileptic agents and their potential side effects and interactions with anesthetic agents are of prime concern during surgical procedures for epilepsy and nonepileptic surgeries. The present article discusses the various anesthetic implications and considerations during management of such patients for epilepsy and nonepilepsy surgery. Key words: Anesthesia, epilepsy, pseudo‑seizures, seizures, status epilepticus
Introduction Epilepsy is the second most common neurological disorder, after stroke. The age‑adjusted incidence in developed countries is 24‑53 per 1,00, 000 person years. The incidence Access this article online Website
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is higher in males and in lower socioeconomic class. In India the overall prevalence rate of epilepsy is 5.59 per 1000 population.[1‑3] Management of an epileptic patient is a huge challenge for the attending anesthesiologist during the perioperative period. Various drug interactions of anesthetics with antiepileptics, intraoperative and postoperative seizures management and management of status epilepticus are few considerations which an anesthesiologist can confront both during emergency or elective surgery.
Classification of epileptic seizures
Epileptic seizures can be classified as partial, generalized, pseudoseizures, nonepileptic seizures and status epilepticus[4-6] [Table 1]. 10
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Bajwa and Jindal: Anesthesia in patient with epilepsy
Table 1: Showing the classification pattern of various seizure disorders Partial seizures
Generalized seizures
Simple Complex Partial onset with generalization
Inhibitory Absence: Typical and atypical Atonic Excitatory Myoclonic Clonic Tonic Tonic–clonic
Pseudoseizures
Causes of epilepsy
It is extremely difficult to ascertain the exact cause of epilepsy and only in 25‑35% of the patients, one can possibly be sure of the exact aetiology.[5,6] Following are few of the known causes of epilepsy: a. Genetic: Juvenile myoclonic epilepsy, benign rolandic epilepsy. b. Trauma: Depressed skull fractures or evidence of intracranial hemorrhage. c. Tumor: Epilepsy is more common with slow‑growing tumors, anterior hemisphere tumors and may be generalized or focal in nature. d. Infection: Bacterial, fungal or tuberculous meningitis and viral encephalitis. e. Cerebral degeneration: Alzheimer’s disease and multi‑infarct dementia. f. Cerebrovascular disease: Cerebral infarction or hemorrhage. g. Multiple sclerosis. h. Alcohol: Lowers seizure threshold. Seizures may occur with binge drinking or withdrawal. i. Metabolic disorders: Hypocalcemia, hyper‑calcemia, hypomagnesemia, hypoglycemia, hyponatremia and hypernatremia. Hepatic and renal failure can also precipitate seizures. In the developed countries predominant causes include developmental disorders and idiopathic causes in children and vascular and degenerative causes in adults, in the developing nations infections, parasites and trauma are the leading causes.[4]
Differential diagnosis
It is extremely essential to diagnose a case of epilepsy for an appropriate and timely therapeutic management. The diseases which are important for differential diagnosis of epilepsy includes syncope, transient ischemic attack, migraine, hyperventilation, narcolepsy, cataplexy, and nonepileptic seizures.[5]
Responsibilities of anesthesiologist in managing an epileptic patient Managing a surgical epileptic patient is a huge challenging task for the attending anesthesiologist and requires a lot of skilful and knowledgeable measures on his part to evaluate
Nonepileptic seizures
Status epilepticus
completely and conduct safe anesthetic procedure.[7] The role of the anesthesiologist in case of epileptic patient acquires important dimensions which includes, 1. Management of status epilepticus in the intensive care. 2. Perioperative management for epilepsy surgery. 3. Perioperative management for nonepilepsy surgery. 4. Management of postoperative seizures in previously normal patient. 5. Management of associated comorbid diseases.
Status epilepticus
Status epilepticus is one of the most dreaded medical emergencies which an anesthesiologist can encounter during emergency or elective surgery in a case of known epileptic patient. Status epilepticus can be defined as a continuous seizure activity lasting >30 min or intermittent seizure activity lasting >30 min during which consciousness is not regained.[1] Status epilepticus should be managed as early as possible, preferably within 30 minutes.[1]
Management of status epilepticus
The diagnosis of status epilepticus is basically made on clinical grounds and the symptomatology is characterized by tonic‑clonic seizures, loss of consciousness, tongue biting, urinary incontinence.[1,8-11] The management of status epilepticus should be initiated as early as possible and includes the following definite measures. • ABC (Airway, breathing and circulation). Primary resuscitative measures to manage an attack of epilepsy are extremely important as these patients are at high risk of injury, airway compromise and other potential serious complications. These primary measures involves. • Airway management. • Administering 100% oxygen. • Securing an IV access. • Sending venous blood sample for biochemical analysis (including RBS). • Closely monitoring the vital signs, ECG and SpO2. • Start IV infusion with normal saline. If hypoglycemia suspected or documented, give glucose. (adults: 100 mg thiamine IV followed by 50 ml of 50% glucose, children: 2 ml/kg of 25% glucose). 11
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• First line therapy: IV Benzodiazipines – Lorazepam (0.1 mg/kg max 2 mg/kg upto 4 mg total dose) or Diazepam (0.1 mg/kg max 5 mg/kg upto 20 mg total dose). • Second line therapy: IV Phenytoin (20 mg/kg max rate adults: 50 mg/min, children: 1 mg/kg/min) or Fosphenytoin (20 mg/kg Phenytoin equivalent (PE) @ 150 mg/min). • If seizures persist: Additional phenytoin (5‑10 mg/kg) or fosphenytoin (5‑10 mg/kg PE). • If seizures still persist: Phenobarbital 20 mg/kg (max @ 60 mg/min). • Intubation and ventilation to maintain normal PaO2 and PaCO2. • Fluid resuscitation should be continued. • If seizures remain uncontrolled propofol or thiopentone infusion. Taper infusions at 12 hours to observe further seizure activity.
Pharmacological therapy and possible drug interactions with anesthetics
Management of an epileptic patient, whether in operative suite or in intensive care unit always involve dedicated team efforts. However, the various drugs used to control epilepsy are not absolutely free from side effects and have their own complications. The current knowledge of potential interactions between anesthetic drugs and antiepileptic agents is limited to few percentage of medical fraternity. Table 2 gives an elaborative review of the antiepileptic medications and their possible interactions with other drugs during the perioperative period.[4,12-14]
Anesthetic management for epilepsy surgery
Surgical management may be indicated for cases with refractory epilepsy. It may be done to resect an epileptogenic focus or to interrupt a seizure pathway and includes[1] i. Temporal lobectomy. ii. Amygdalohippocampectomy. iii. Extratemporal cortical excision. iv. Hemispherectomy. v. Corpus callosotomy. vi. Vagal stimulation. vii. Electrical stimulation of centromedian thalamic nucleus.
Anesthetic considerations
Anesthesia for epilepsy surgery may be required either in the form of general anesthesia or local anesthesia supplemented with sedation. The possible roles of an anesthesiologist during epilepsy surgery include:[15] 1. Monitored anesthesia care during awake craniotomy. 2. Inducing intraoperative seizures for intraoperative electrocorticograhy. 3. Brain protection, maintenance of intracranial hemodynamics and preventing rise in intracranial pressure. 12
Bajwa and Jindal: Anesthesia in patient with epilepsy
4. Rapid postoperative recovery to provide for early neurological assessment. 5. Management of refractory seizures. Besides the possible role in epilepsy surgery, the responsibilities of anesthesiologist also extend to the preoperative period. During the diagnostic interventions preoperatively the role of anesthesiologists includes[1] 1. Providing monitored anesthesia care for radiological procedures like magnetic resonance imaging and positron emission tomography. 2. Monitored anesthesia care for stereotactic electrode insertion. 3. General anesthesia for epidural electrode and grid placement. 4. Thiopentone test for localisation of seizure focus. With gradual increase in thiopentone blood levels, β‑activity occurs in normal neural tissue on electroencephalography while seizure focus shows abnormal response. 5. Wada test is used to determine dominant cerebral hemisphere using amobarbital injected into carotid artery (to lateralize cerebral speech dominance).
Anesthetic management
Anesthetic management of patients with epilepsy involves numerous considerations preoperatively, perioperatively and during the postoperative period.
Preanesthetic evaluation
In addition to routine preanesthetic evaluation, one should assess for differential diagnosis of associated seizure disorders which can be attributed to various disease states such as Huntington’s chorea, tuberous sclerosis, neurofibromatosis, lesch nyhan sundrome.[1] Similarly, possible anesthetic and antiepileptic drug interactions should be considered as hepatic enzyme induction can lead to requirement of higher doses of nondepolarizing muscle relaxants and opioids. The clinical history and examination should also include for the possible presence of various side effects of ongoing epileptics such as gingival hypertrophy, megaloblastic anemia and so on.
Premedication
Premedicate with benzodiazepine, atropine or glycopyrrolate (as patients head and neck are inaccessible during intra‑op period) and continue with anticonvulsants on the morning of surgery.[1]
Monitoring
Intraoperative monitoring includes electrocardiography, noninvasive blood pressure, pulse oximetery, end tidal carbon dioxide, temperature and urine output. Central venous pressure monitoring may be required if significant blood loss is anticipated.[1,15,16]
Awake craniotomy
It is performed when epileptogenic focus is close to eloquent areas of the brain,[1] usually temporal
Mech of action
Modulating postsynaptic inhibitory action of γ‑aminobutyric acid (GABA) and blocking postsynaptic excitation by glutamate
Inhibitor of enzyme systems that inactivate GABA
Decreases sodium ion current, enhances effect of GABA, blocks N‑methyl‑D‑aspartate (NMDA) receptors
Blocks votage dependant sodium channels
Changes ionic conductance of sodium channels with membrane stabilising effect
Designed to prevent formation of epoxide metabolite of carbazepine
Stabilizing voltage sensitive sodium channels
Inhibits votage sensitive sodium current and facilitates GABA action
Metabolized to phenobarbital and other active metabolite
Facilitaes GABAergic action
Blocks non‑NMDA glutamate receptors and sodium channels, potentiates GABA action
Drug
Phenobarbital
Valproic acid
Felbamate
Phenytoin
Carbamazepine
Oxcarbazepine
Lamotrigine
Gabapentine
Primidone
Clonazepam
Topiramate
Partial seizures, tonic clonic seizures, lennox gastaut syndrome
Myoclonic seizures
Partial and generalized partial seizures, pain syndromes like erythromelalgia, reflex sympathetic dystrophy and neuropathic pain
Adult partial and generalised epilepsy, lennox gastaut syndrome
Convulsive and nonconvulsive partial epilepsy, trigeminal and glossopharyngeal neuralgia, bipolar disorder and alchohol withdrawl syndrome
Partial and generalised epilepsy
Isolated partial epilepsy, secondary generalise epilepsy, lennox gastaut sundrome
All types of epilepsy
For all types of epilepsy except primary generalized nonconvulsive type
Uses
Dizziness, nervousness, cognitive disturbances, ataxia, depression, diarrhea, glaucoma, loss of appetite and weight loss, paresthesias and urolithiasis, metabolic acidosis
Personality changes manifested as behavioral disorders, hyperactivity, irritability and difficulty concentrating, especially in children. Depression in the elderly. Sialorrhea and increased bronchial secretion
Fatigue, depression, psychosis, decreased libido, skin changes, leukopenia, thrombocytopenia and SLE
Sedation, diplopia, dizziness, ataxia, skin changes, weight gain, nausea and leucopenia
Dizziness, diplopia, tremor, insomnia, aggression, ataxia, allergic dermatitis, Stevens‑Johnson syndrome, headache, nausea, vomiting and blood dyscrasias
Sedation, dizziness, headache, amnesia, ataxia, diplopia, depression, insomnia, anxiety, nausea and vomiting, diarrhoea, hyponatremia, acne, alopecia and urticaria
Sedation, diplopia, dizziness, neutropenia, nausea, drowsiness, diarrhea, jaundice, oliguria, hypertension, cardiac arrhythmias, hyponatremia, agranulocytosis, aplastic anemia, allergic dermatitis, Stevens‑Johnson syndrome and systemic lupus erythematosus
nystagmus, diplopia, dizziness (vestibular cerebellar dysfunction), ataxia, nausea and vomiting, gingival hyperplasia, depression, megaloblastic anemia, drowsiness, agranulocytosis, aplastic anemia, allergic dermatitis, Stevens‑Johnson syndrome, hyperglycemia, hepatotoxicity, pancreatitis, acne, rough skin, hirsutism, teratogenicity and Dupuytren’s contracture
Insomnia, anorexia, nausea, headache, irritability, aplastic anemia and hepatotoxic effects
Tremors, weight gain, dyspepsia, nausea and vomiting, anorexia, alopecia, edema, encephalopathy (due to increased levels of ammonia), teratogenicity, agranulocytosis, aplastic anemia, allergic dermatitis, Stevens‑Johnson syndrome, hepatotoxicity, platelet changes that can lead to bleeding, and pancreatitis
Sedation, depression, hyperactivity (in children), confusion (in elderly), skin changes, megaloblastic anemia, osteomalacia, nystagmus, ataxia, abnormal collagen deposition (Dupuytren’s contracture), attacks of porphyria
Side effects
Table 2: Showing the indications, side effects and clinical actions/significance of various anti‑epileptic drugs
Contd...
Chronic use induces metabolism of enflurane, halothane and isoflurane
Induces hepatic microsomal system
Enhances hepatic oxidation and conjugation of liposomal drugs
Induces oxidative metabolism of liposomal drugs including thiopentone, propofol, midazolam, opiods and nondepolarising neuromuscular blockers
When used with other anticonvulsants its dose should be reduced by 20‑30%
Displaces diazepam from the binding site, hepatic microsomal enzyme inhibitor
Hepatic microsomal enzyme induction
Interaction
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Bajwa and Jindal: Anesthesia in patient with epilepsy
13
Irritability, Cushing syndrome, electrolyte disturbances (hypokalemia), impaired glucose tolerance, dilation of cerebral ventricles, increased cerebrospinal fluid, hypertension, cardiomyopathy, and sepsis
Sedation, asthenia, diplopia, hypohidrosis, skin changes, StevensJohnson syndrome, dizziness, headache, ataxia, anorexia, agitation, irritability, and nephrolithiasis, metabolic acidosis
Numerous drugs used in anesthesia have potential drug interactions with anti-epileptic agents which can be highly detrimental during surgical procedures.[1,4,7,15]
Benzodiazepines
It is also used as first‑line anticonvulsant drugs besides sedation purpose.
Propofol
West syndrome
Blocking voltage dependent sodium channels and T‑type calcium channels,
Cholinergic and serotonergic modulation
Zonisamide
ACTH and corticosteroids
Partial seizures
At ususal doses it is epileptogenic and thus should be avoided.
Uses
Etomidate
Blockage of GABA reuptake
its antiepileptic activity is related to inhibition of pre and postsynaptic chloride channels mediated by GABA. It is used for sedation, induction and maintenance of general anesthesia. It can cause abnormal movements as opisthotonus and myoclonia in normal as well as epileptic patients.
Tiagabine
Partial, secondarily generalised, generalised tonic clonic, myoclonic seizures, lennox gastaut syndrome
Dizziness, asthenia, somnolence, anxiety, nausea, nervousness, tremors, abdominal pain and cognitive disorders
Anesthetic drugs and epilepsy
Binds to protein A2 related to release of glutamate
Partial seizures, tonic clonic seizures
For other surgeries where general anesthesia is used, induction may be done with thiopentone or propofol. Maintenance is done using nitrous oxide, narcotic and sub‑MAC concentrations of isoflurane or sevoflurane. Early awakening allows rapid neurological assessment. Postoperatively pain relief is important. Blood levels of antiepileptics should be obtained to adjust the doses accordingly.
Levetiracetam
Drowsiness, weakness, dizziness, ataxia, amnesia, depression, anxiety, anorexia, diarrhea, dyspepsia, skin changes and pancytopenia
lobe epilepsy. Electrocorticography (ECoG) may be used to identify the epileptogenic focus. However, anesthetics have a depressant effect on ECoG. Neurolept anesthesia (combination of droperidol and fentanyl) was traditionally used for management of anesthesia. However, the side effects include postoperative extrapyramidal excitation, unconsciousness, restlessness and confusion. Propofol is now the preferred agent. Alfentanil, remifentanil or fentanyl are used for intraoperative analgesia. Field block is used to provide local anesthesia.
Mech of action
Table 2: Contd... 14
Bajwa and Jindal: Anesthesia in patient with epilepsy
Drug
Side effects
Interaction
Anesthesia: Essays and Researches; 7(1); Jan-Apr 2013
It is anticonvulsant at high doses and proconvulsant at clinical doses.
Ketamine
Droperidol
It has no proconvulsant activity.
Dexmeditomidine
It has no pro or anticonvulsant activity. Sedation due to dexmeditomidine shows EEG pattern similar to stage II sleep. It is used in autistic children for EEG recording. However, this drug has numerous beneficial effects when used through different routes. It prolongs analgesia of local anesthetics when used in neuraxial blocks, attenuates pressor response when used before induction of anesthesia, reduces requirement of postoperative analgesics and causes reduction of shivering postoperatively after general anesthesia.[17‑19]
Anesthesia: Essays and Researches; 7(1); Jan-Apr 2013
Bajwa and Jindal: Anesthesia in patient with epilepsy
Clonidine
It has been used in autistic patients for sedation during EEG recording. Its role is similar to dexmedetomidine when used through all the above mentioned routes but has lesser affinity at α‑2 receptors as compared to dexmedetomidine.[17,20,21] All barbiturates, except methohexitol, have significant anticonvulsant activity.
Opioids
Mepiridine, due to its metabolite normeperidine, has proconvulsant activity. In patients with renal failure, advanced malignancy, sickle cell disease, prolonged use, enzymatic induction with anticonvulsants, normeperidine gets accumulated and can lead to seizures. Morphine, though devoid of anticonvulsant activity, can cause tonic clonic activity when used in epidural space. High doses of phenylpiperidine derivatives (fentanyl, alfentanil, sufenanil and remifentanil) should be avoided in epileptic patients.
Nitrous oxide
Its epileptogenic potential is very low and can be safely used in epileptic patients.
Halothane
Has a potent anticonvulsant activity. Can cause epileptiform EEG and contraindicated in epileptic patients.
seizures,
is
Isoflurane
Has potent anticonvulsant activity.
Sevoflurane
Avoid use at concentration above 1.5 MAC and in presence of hypocapnia.
Desflurane
Has no proconvulsant activity.
Neuromuscular blockers
No reported proconvulsant activity.
Anticholinergics
Atropine, scopolamine and glycopyrrolate can be used in epileptics.
Local anesthetics
Barbiturates
Enflurane
Anticholinesterases
a. Nondepolarizing blockers: Phenytoin and carbamazepine used chronically increases hepatic clearance of rocuronium, pancuronium, vecuronium, cisatracurium, decreasing their duration of action. Atracurium and mivacurium are not metabolised by hepatic enzymes and hence their duration if action is not affected. Acute administration of phenytoin potentiates the neuromuscular blockade of rocuronium. Though laudanosine, an atracurium metabolite has been postulated to be proconvulsant, yet there is no report of such episode in human beings. b. Depolarizing blocker succinylcholine: Its duration of action is slightly increased.
At subtoxic doses they are anticonvulsants, sedatives and analgesics while at higher concentrations can cause seizure activity.
Antiemetics
Are of five main classes; dopamine antagonists, anticholinergics, antihistaminics, 5‑HT3 anatgonists, steroids. Dopamine antagonists (phenothiazines‑prochlorperazine, butyrophenones‑droperidol, benzamides‑metoclopramide) can cause extrapyramidal effects and dystonia which can be confused with epileptic activity.
Anesthetic management for nonepilepsy surgery
• Preoperatively a careful review of medical history, factors triggering seizures (fasting, stress, sleep deprivation, alcohol, and drugs), comorbidities, mental retardation, hypotonia, risk factors for aspiration and difficult airway should be assessed.[4,7,15] Evaluation by a neurologist preoperatively is preferable. Anticonvulsants should be continued as scheduled on the day of surgery. Midazolam is usually used for premedication. However, some anticonvulsants and ketogenic diet can lead to sedation. • Intraoperative monitoring depends upon the surgical procedure and the patients clinical condition. • For induction propofol or thiopentone may be used. Ketamine and etomidate are best avoided. Opioids other than meperidine may be used. Total intravenous anesthesia (TIVA) with propofol and fentanyl can also be used safely in such patients. [Ref] Neuraxial opioids can also be safely used. • Avoid intraoperative hypoxia, hypotension, hypocapnia and hyponatremia. • Regional anesthesia can be safely used. Coagulation profile, however, should be assessed because of propensity of certain anticonvulsants to precipitate coagulation disturbances. • Postoperatively anticonvulsants should be started as early as possible. If fasting time is 12‑14 hours, parenteral replacement for oral drugs may not be required. However, where fasting time exceeds 24 hours parenteral replacement is necessary.
Seizures occurring as a complication of anesthesia
Postoperative seizures, though rare, are a recognized complication of anesthetics.[4,7,15] Patients at risk are generally those who already have epilepsy, especially those with poor preoperative control and those undergoing brain surgeries. Rarely seizures can occur as isolated 15
Anesthesia: Essays and Researches; 7(1); Jan-Apr 2013
event in previously normal patient. This should prompt search for structural or chemical brain abnormality.
Risk factors for seizures postperatively
Vigil has to be exercised during post-operative period as numerous risk factors listed below can be potential cause of seizures.[22] 1. Pre‑existing epilepsy or seizure disorder, especially if poorly controlled. 2. Lengthy surgery or surgery that lasts longer than the effectiveness of the last dose of seizure medication in epileptics. 3. Pre‑existing brain abnormality such as tumor, aneurysm or scarring. 4. Alcoholism and alcohol withdrawal. 5. Illicit drug use. 6. Local anesthesia in large doses. 7. Certain anesthetics in combination with any of the above. 8. Chemical or electrolyte abnormality. Perioperative seizures, if prolonged, can cause brain damage due to hypoxia, apnea, prolonged postoperative mechanical ventilation, and delayed awakening from anesthesia. Physiological cardiac and respiratory regulation may be impaired. There may be tachycardia and tachypnea, apnea and bradycardia or sudden death due to autonomic instability, which causes cardiac arrhythmias or neurogenic pulmonary edema.[4]
Bajwa and Jindal: Anesthesia in patient with epilepsy
dystonic movements or epileptiform activity, but drug‑induced seizures are rare. Postoperative seizures are more common after neurosurgery. Pseudo‑epileptic seizures in the postoperative period resemble tonic–clonic seizures but are not associated with abnormal electrical discharges in the brain.[22] They tend to be associated with a history of convulsions and/or psychosomatic illness. They are characteristically flamboyant, last longer than 90 s and are associated with asynchronous limb movements, side‑to‑side head movements, closed eyes (including a resistanxce to eye opening) and maintenance of papillary reflexes. There is no cyanosis or postictal period but there may be incontinence or tongue‑biting. Seizures may settle with reassurance. Plasma prolactin concentrations tend to be raised after epileptic seizures and normal after pseudo‑seizures. However, the diagnosis of pseudo‑seizures remains primarily clinical. It is possible for both epileptic and pseudo‑epileptic seizures to coexist.
References 1. 2. 3. 4.
Management includes maintaining a patent airway with adequate ventilation and protect the patient from injuries resulting from seizures. Monitoring should be performed using cardioscope, blood pressure and pulse oximetry.[4]
5.
Should convulsions persist for more than 5 minutes, intravenous benzodiazepine should be used. Preffered drug is lorazepam. Alternatively diazepam (5‑20 mg) may be used. If convulsions persist, a second dose of benzodiazepine with phenytoin (20 mg/kg over 30 minutes) may be used. For refractory seizures, phenobarbital (1.5 mg/kg/min or 100 mg/70 kg/min can be used with a maximum dose of 20 mg/kg or 1,000 mg/70 kg), midazolam (0.1‑0.3 mg/kg in 2‑5 minutes, followed by infusion of 0.05 to 0.4 mg/kg/hour), propofol (1‑2 mg/kg followed infusion of 2‑10 mg/kg/h), thiopental (5‑10 mg/kg in 10 minutes, followed by infusion of 100‑400 mg/h), lidocaine (1.5‑2 mg/kg in 2‑5 minutes, followed by infusion of 2‑3 mg/kg/h for 12 hours), isoflurane (0.5‑1.5%) and ketamine (50‑100 mg followed by infusion of 50‑100 mg/h).[4]
7.
Postoperative pseudo‑epileptic seizures
Postoperative shivering is common complication of anesthesia. Various drugs and adjuvants have been successfully used during peri‑op period for the prevention of postoperative shivering.[19] It can be confused with epileptic seizures. Some anesthetic drugs can cause 16
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Anesthesia: Essays and Researches; 7(1); Jan-Apr 2013 18. Bajwa SS, Kaur J, Singh A, Parmar SS, Singh G, Kulshrestha A, et al.Attenuation of pressor response and dose sparing of opioids and anaesthetics with pre‑operative dexmedetomidine. Indian J Anaesth 2012;56:123‑8. 19. Bajwa SJ, Gupta S, Kaur J, Singh A, Parmar SS. Reduction in the incidence of shivering with perioperative dexmedetomidine: A randomized prospective study. J Anaesthesiol Clin Pharmacol 2012;28:86‑91. 20. Bajwa SJ, Kaur J, Bajwa SK, Bakshi G, Singh K, Panda A. Caudal ropivacaine‑clonidine: A better post‑operative analgesic approach. Indian J Anaesth 2010;54:226‑30. 21. Bajwa SJ, Bajwa SK, Kaur J, Singh A, Singh A, Parmar SS. Prevention of hypotension and prolongation of postoperative analgesia in emergency
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How to cite this article: Bajwa SJ, Jindal R. Epilepsy and nonepilepsy surgery: Recent advancements in anesthesia management. Anesth Essays Res 2013;7:10-7. Source of Support: Nil, Conflict of Interest: None declared.
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