Clinical Neurology and Neurosurgery 136 (2015) 5–9
Contents lists available at ScienceDirect
Clinical Neurology and Neurosurgery journal homepage: www.elsevier.com/locate/clineuro
Management of idiopathic intracranial hypertension with a programmable lumboperitoneal shunt: Early experience Fahad Alkherayf a,b,c,∗,1 , Hussam Abou Al-Shaar d,1 , Michael Awad a,b a
C2 Clinic – Division of Neurosurgery, The Ottawa Hospital, 1053 Carling Avenue, Ottawa, Ontario, Canada Division of Neurosurgery, The University of Ottawa, Ottawa, Canada The Ottawa Hospital Research Institute (OHRI), Ottawa, Canada d College of Medicine, Alfaisal University, Riyadh, Saudi Arabia b c
a r t i c l e
i n f o
Article history: Received 1 April 2015 Received in revised form 11 May 2015 Accepted 13 May 2015 Available online 27 May 2015 Keywords: Idiopathic intracranial hypertension Programmable valve Lumboperitoneal shunt Hydrocephalus Complications
a b s t r a c t Objective: To evaluate the clinical outcomes and complications rate among idiopathic intracranial hypertension (IIH) patients who underwent lumboperitoneal (LP) shunt insertion with a programmable Strata valve. Methods: We retrospectively evaluated patients who underwent LP shunt with a programmable Strata valve insertion at the University of Ottawa Civic Hospital from November 2012 to June 2013. The demographic data, clinical symptoms, opening pressure, pre-operative and post-operative visual fields, neuroimaging, visual acuity, disc status, and complications were recorded and analyzed. Results: Seven female patients with IIH underwent insertion of an LP shunt with a programmable Strata valve. The mean opening pressure was 35.8 cm H2 O. The initial valve setting was 1.5, and four patients required post-operative valve pressure adjustment. All patients showed significant improvement in objective visual testing at follow-up as well as less frequent headaches. None of the patients developed intra- or post-operative complications. Conclusion: LP shunts with programmable Strata valve systems are a potential alternative to conventional LP and programmable ventriculoperitoneal shunt systems as well as optic nerve sheath fenestration, due to their potential in avoiding brain injury, lower failure and complication rates, lower intracranial hypotension incidence, and flexibility in adjusting valve pressure settings post-operatively evading under- and overdrainage complications. They should be considered for the management of IIH instead of early design LP systems and VP shunts. A randomized multi-center trial should be conducted to compare the efficacy of these surgical techniques. © 2015 Elsevier B.V. All rights reserved.
1. Introduction The use of lumboperitoneal (LP) shunts has been well documented as a treatment modality for patients with idiopathic intracranial hypertension (IIH). There are a number of advantages to LP shunts when compared with other treatment modalities for IIH, such as stereotactic ventriculoperitoneal shunts (VP) and optic nerve sheath fenestrations (ONSF). LP shunts avoid intracranial risks, such as cerebral hemorrhage, seizures, and shunt
Abbreviations: IIH, idiopathic intracranial hypertension. ∗ Corresponding author at: C2 Clinic – Division of Neurosurgery, The Ottawa Hospital, 1053 Carling Avenue, Ottawa, Ontario, Canada. Tel.: +1 6137971239. E-mail address: [email protected] (F. Alkherayf). 1 Both the authors contributed equally to this study. http://dx.doi.org/10.1016/j.clineuro.2015.05.018 0303-8467/© 2015 Elsevier B.V. All rights reserved.
malposition. Additionally, LP shunts may be preferable for patients with small ventricles because of the ease of shunt insertion [1,2]. Early designs of LP shunt systems were composed of a valveless silastic tube, and the diversion of cerebrospinal fluid (CSF) is entirely dependent on the resistance and gravity encountered through the silicon catheter. One criticism of LP shunts is the potential development of low-pressure symptoms caused by CSF overdrainage. Therefore, it was necessary to incorporate a valve into the LP shunt system, which was established by Murtagh in 1967 in order to decrease the incidence of such a complication [3]. A limitation of these valves was the fixed pressure setting established at the time of surgery, which may result in under- or overdrainage complications post-operatively, requiring subsequent shunt revision(s). The development of low-pressure symptoms requiring LP shunt revision has been reported to be as high as 25% [4]. However, with the recent advances in modern technology, such as the introduction
6
F. Alkherayf et al. / Clinical Neurology and Neurosurgery 136 (2015) 5–9
Fig. 1. Photographs of the programmable Strata valve (Medtronic, Inc.).
of programmable valves and small lumen peritoneal catheters, the incidence of intracranial hypotension has decreased, and it is now possible to adjust the valve pressure setting post-operatively to avoid symptoms of over- or underdrainage [1,5]. Therefore, the use of these programmable LP shunts has drastically reduced the need for subsequent revision procedures [1,2,4]. Various programmable valve LP shunt systems have been introduced to the market, and each has its advantages and disadvantages. The Strata LP valve (Medtronic, Inc.) incorporates a ball-and-cone pressure valve (Fig. 1). With this shunt, flow control depends on the resistance of the ball and cone and the degree of resistance determines the performance level of the valve. In addition, retrograde flow is prevented by the ball and cone [2]. The valve pressure setting can be adjusted easily using an external magnet to reach the desired pressure setting. Therefore, it is essential to check and adjust the valve pressure setting in patients after the exposure to large magnetic fields like magnetic resonance imaging (MRI). Programmable valves have been used in VP shunts for decades. However, their use in LP shunt procedures is relatively new. Most of the reported literature describes the use of traditional LP shunts in the management of IIH, and there are few reports in the literature describing the use of programmable valve LP shunts in IIH patients. In addition, most of the current literature comparing the efficacy between LP and VP shunt systems does not consider the LP shunts with programmable valves, resulting in an underestimation of this potentially highly effective alternative. In this account, we report our early experience with programmable LP shunts in the management of IIH at the Ottawa Hospital. 2. Methods We performed a retrospective review and analysis of the clinical records of patients who underwent programmable Strata (Medtronic, Inc.) LP shunt placement by the senior author (F.A.) at the Ottawa Hospital between May 2012 and June 2013 with a minimum follow up of one year. Our inclusion criteria included adult patients who were newly diagnosed with IIH (based on modified Dandy criteria (Table 1)) [6] with visual impairment and with an LP opening pressure of 25 cm H2 O or more at the time of presentation. Patients with previous CSF diversion or previous cranial or abdominal surgeries were excluded. The study was approved by Table 1 Modified Dandy criteria for idiopathic intracranial hypertension [6]. Symptoms of elevated intracranial pressure (headache, nausea, vomiting, transient visual obscurations, or papilledema) Absence of localizing signs in neurological examination with the exception of false localizing signs (e.g., abducens or facial nerve palsies) Patient is awake and alert Normal CT/MRI findings without evidence of thrombosis Lumbar puncture opening pressure of >25 cm H2 O and normal biochemical/cytological composition of CSF No other explanation for raised intracranial pressure
the Research Ethic Board at the Ottawa Hospital Research Institute (OHRI). Informed consent was obtained from all patients involved in the study. Patient demographics, including age, gender, diagnosis, clinical symptoms, opening pressure, pre- and post-operative visual acuity, visual fields, disc status, neuroimaging, and intraand post-operative complications were assessed. The initial valve settings and subsequent adjustments were also reviewed. The Strata programmable valve (Medtronic, Inc.) provides the following full range of performance levels (acceptable pressure ranges are given in parentheses): 0.5 setting (0–3 cm H2 O), 1.0 setting (1–6 cm H2 O), 1.5 setting (5.5–11.5 cm H2 O), 2.0 setting (10.5–17 cm H2 O), and 2.5 setting (15.5–22.5 cm H2 O). The valve is composed of a reservoir and proximal and distal occluders that allow for injection, CSF sampling, and proximal or distal flushing. The valve performance level can be verified through the use of a built-in adjustment system or using a radiographic confirmation. The small lumen peritoneal catheter consists of firmer catheter tubing than conventional LP shunts, which reduces the risk of occlusion or kinking. The small inner diameter provides an average flow resistance of 0.1 cm H2 O/cm catheter length at a constant flow rate of 20 ml/h. The flow-limiting properties of the small lumen peritoneal catheter may decrease the risk of overdrainage [2]. The lumbar catheter can reach up to 84 cm in length while the peritoneal catheter can reach up to 120 cm in length. 3. Surgical technique Patients underwent general anesthesia and endotracheal intubation in the lateral decubitus position with routine skin preparation and draping. Three incisions were made, including a 1cm lumbar incision (L3–L4), a 5-cm flank incision, and a transverse abdominal incision. A total of 10–20 cm of the lumbar catheter was inserted into the subarachnoid space using a Tuohy needle, and the placement of the catheter was confirmed via CSF flow. A subcutaneous pouch was fashioned using curved mayo scissors to house the valve. Following the dissection of the abdominal wall layers into the peritoneum, a small lumen peritoneal catheter was inserted and tunneled between the lumbar and abdominal incisions. The lateral incision was used to move the catheter through the subcutaneous pouch. The pre-programmed valve was anchored with the use of sutures. Flow confirmation was obtained and all three incisions were closed in layers. 4. Results Between May 2012 and June 2013, seven female patients underwent placement of an LP shunt with a programmable Strata valve (Medtronic, Inc.) at the Ottawa Hospital (Table 2). The mean patient age was 33.2 years (range 23–46). Data for pre- and post-operative visual acuity, visual fields, and optic disc status are shown in Table 3. One patient (14.3%) failed to attend the follow-up with their ophthalmologist for a postoperative visual assessment.
F. Alkherayf et al. / Clinical Neurology and Neurosurgery 136 (2015) 5–9
7
Table 2 Patients demographics. Patient
Age
Gender
Urgency
Opening pressure (cm H2 O)
Initial valve pressure setting
Final valve pressure setting
1 2 3 4 5 6 7
33 32 46 34 33 32 23
F F F F F F F
Elective Elective Elective Emergent Elective Elective Elective
42 29 27 27 30 40 >55
1.5 1.5 1.5 1.5 1.5 1.5 1.5
0.5 2 2 1 1.5 1.5 1.5
Table 3 Pre-operative vs. post-operative visual function. Pre-Op VA
Pre-Op VF
Pre-Op disc status
Post-Op VA
Post-Op VF
Post-Op disc status
1
OD: 20/30 OS: 20/25
Papilledema (OU)
OD: 20/25 OS: 20/20
Improved (OU)
Normal (OU)
2
OD: 20/20 OS: 20/150* OU: 20/20 OD: 20/25 OS: 20/30 OD: 20/20 OS: 20/20* OD: 20/20 OS: 20/25* OU: 20/20
Generalized constriction extended from inferior quadrant (OU) Mild loss (OD) Depressed (OS) Normal (OU) Constriction (OU)
Optic atrophy L > R (OU) Mild gliotic changes (nasal surface) (OU) Papilledema (OU)
OD: 20/20 OS: 20/80 OU: 20/20 OD: 20/20 OS: 20/25 OD: 20/20 OS: 20/20* OD: 20/20 OS: 20/20* –
Improved (OU)
Optic atrophy (OU)
Normal (OU) Normal (OU)
Mild gliotic changes (OU) Normal (OU)
Normal (OD) Mild inferior field loss (OS) Normal (OU)
Normal (OU)
3 4 5 6 7
Mildly depressed (OD) Significant reduction (OS) Enlarged blind spot (OU)
Papilledema (OU)
Loss of peripheral vision (OU)
Papilledema (OU)
Papilledema (OU) + Secondary exudate
–
Minimal disc fullness nasally (OU) -
OD, oculus dexter (right eye); OS, oculus sinister (left eye); OU, oculus uterque (bilateral); VA, visual acuity; VF, visual fields; –, no follow-up; *, afferent pupillary defect detected.
The mean opening pressure detected at the initial evaluation was 35.8 cm H2 O (range 26 to >55 cm H2 O). Six out of seven (85.7%) procedures were elective. The valve pressure setting during the operation was set at 1.5. Because of the high intracranial pressure (ICP) encountered among patients with IIH, we elected to start our shunts with this pressure setting with serial patient assessments post-operatively, monitoring for the development of overor underdrainage symptoms, which requires pressure adjustment. The valve pressure was adjusted in 4 patients based on their postoperative symptoms and clinical and radiological findings at 4 week follow-up as indicated in Table 2. No intra- or post-operative complications were noted in our series. All patients demonstrated post-operative improvements in visual function. 5. Discussion IIH is an uncommon condition, defined as elevated intracranial pressure (ICP) without the presence of a brain mass, hydrocephalus, or changes in the cerebrospinal fluid profile [1]. Quincke was the first to describe this condition in 1893 as a meningitis serosa after his observation of patients with elevated ICP in the absence of a brain lesion [7]. In 1904, Nonne described the condition as a pseudotumor cerebri to highlight the high ICP levels commonly observed in these patients mimicking the findings of brain tumors [8]. This condition was further characterized by Walter E. Dandy in 1937 when he outlined the IIH Inclusion Criteria [9]. A diagnosis of IIH is based on excluding other causes of elevated ICP. Dandy’s original criteria were refined by Digre and Corbett in 2001 (Table 1) and are currently used in clinical practice [6]. Imaging techniques can aid in the diagnosis of IIH. Most of our patients demonstrated the typical imaging findings encountered among IIH patients. The ventricular size is typically decreased or normal in computed tomography (CT) scans [10]. Other CT findings have been reported in the literature, including the widening of the optic nerves and empty sella syndrome [11]. MRI may demonstrate flattening of the posterior sclera, empty sella syndrome, tortuosity and dilation of the optic nerves, and slight enhancement of
the optic disc upon contrast administration [12,13]. Moreover, a lumbar puncture should be performed in IIH patients when other modalities have failed to confirm a diagnosis. The management of IIH remains controversial and can be classified into behavioral modifications, medical treatment, or surgical intervention [1,14,15]. Surgical management is essential when behavioral and medical interventions fail to control patients’ symptoms [1,14,15]. LP and VP shunting, venous sinus stenting, and ONSF are potential surgical therapeutic modalities, with VP and LP shunts being the most commonly used for the management of IIH [1,15]. ONSF and sinus stenting are not typically the first line of surgical treatment and are generally considered only when CSF diversion fails to relieve patients’ symptoms [16,17]. Studies have demonstrated that ONSF can prevent further deterioration of visual function with moderate efficacy in the treatment of papilledema in IIH patients [16]. Nonetheless, a great number of patients who underwent ONSF had a recurrence of symptoms within one year of the procedure, indicating high failure rates [15,17]. According to Spoor et al., only 75% of ONSFs remain functional 6 months after surgery. This value decreased to 66% at 12 months, 55% at 36 months, 38% at 60 months, and 16% at 72 months [17]. Typically, patients with IIH have small ventricles making the placement of the VP shunt catheter challenging, with an increased risk of shunt malfunctions and/or intracranial injuries. Additionally, non-programmable VP shunts are typically associated with over- or underdrainage of CSF leading to shunt malfunction. The use of programmable VP shunts with neuronavigation has helped to reduce the incidence of these complications [18–21]; however, they remain the primary challenge that lead to shunt malfunction. Recent studies have shown a failure rate of nearly 14% in patients managed with VP shunts [5]. VP shunts also carry the risk of intracranial infection; the rate of infection is variable in the literature, with a rate of 4–7% reported in many studies [22]. LP shunting is an alternative method for the treatment of IIH patients. It avoids the risk of intracranial injuries. However, the increased risk of developing acquired Chiari malformation is one of the major side effects of LP shunting. This complication is most
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likely related to the unregulated CSF flow through the standard LP shunts [18–21]. Additionally, standard LP shunts are associated with high failure rates, which can reach up to 11% [5]. Since the establishments of LP shunt systems with valves in 1967, various refinements have been attempted to allow noninvasive post-operative valve pressure adjustments. The Codman Hakim programmable valve was one of the first systems employed to allow such adjustment. The Codman Hakim programmable valve is a differential pressure valve that utilizes digitally-coded magnetic impulses to position a magnetically driven rotor regulating the preload of a flat spring that rests on a ruby ball valve. The opening pressure of the valve is programmed in the range 3–20 cm H2 O [23]. However, CSF overdrainage due to sudden increase in hydrostatic pressure and the valve’s tendency to rotate in the soft tissues of the abdomen were the major limitations of that programmable valve system. Therefore, it was essential to add a flat-bottomed stage to prevent the valve from rotation and a Siphonguard add-on device to respond to rapid changes in hydrostatic pressure [19]. The development of the new LP shunt with a programmable Strata valve (Medtronic, Inc.) system may have the same advantages as the programmable VP shunt without having the intracranial complications. It also has the advantages of the standard LP shunt in addition to decreasing the risk of developing the acquired Chiari malformation. The literature suggests that 95% of patients experience resolution of headaches and up to 100% experience improvement of their symptoms after programmable LP shunt placement [18,24]. Low-pressure symptoms are a common complication reported in patients undergoing traditional LP valve insertions; however, two studies found that these symptoms were reversible with programmable valves. Additionally, acquired Chiari malformation was not observed in any of those patients [18–20]. Other complications associated with LP shunting including shunt obstruction, migration, malposition, infection, arachnoiditis, scoliosis, and radiculopathy have been reported in the literature [18,25]. None of our patients developed acquired Chiari malformation or any of the other complications after programmable LP shunt insertion. In our series, all patients demonstrated objective post-operative improvements in their visual symptoms as well as less frequent headaches. These results are comparable to a previous series by Toma et al., which demonstrated a resolution of visual symptoms in 13/15 (87%) patients who underwent programmable valve placement [2]. In our small series, we elected to start our shunt setting at 1.5 with continuous assessment of patient symptoms post-operatively. Because of the high ICP in IIH patients and based on our data, we recommend 1.5 as a suitable starting setting for IIH patients. We believe that this initial pressure setting is advisable in most patients to avoid post-operative under- and overdrainage complications. However, in the presence of under- or overdrainage complications, LP shunts with programmable Strata valves (Medtronic, Inc.) allow for flexible valve pressure setting adjustment post-operatively. In our cohort, 4 patients required post-operative pressure adjustment based on their post-operative symptoms and clinical and radiological findings. Based on our results, we believe that this programmable LP shunt system is a potential alternative for treating patients with IIH due to brain tissue avoidance and low long-term failure rates. It may also decrease the risk of developing acquired Chiari malformation and low-pressure symptoms. In our study, none of the patients developed intra- and/or post-operative complications or shunt failure. The retrospective nature of our study, the small sample size, the relatively short follow-up period, and the lack of a VP comparison group are the main limitations implicated in this study. However, our study highlights the effectiveness of LP shunt with
a programmable Strata valve (Medtronic, Inc.) in managing IIH patients; it also sheds light on this new modality to be considered in those patients. In addition, our study sets the basis for future prospective randomized multi-center clinical trials to compare this programmable LP shunt system with other IIH treatment modalities. 6. Conclusion LP shunting with a programmable Strata valve (Medtronic, Inc.) system is a promising surgical modality that improves the symptoms of IIH patients and may have fewer complications in comparison to the conventional LP and programmable VP shunt systems due to its potential in evading brain injury, its lower failure and complication rates, lower intracranial hypotension incidence, and flexibility in adjusting the valve pressure settings post-operatively to avoid under- and overdrainage complications. A prospective randomized multicenter clinical trial should be conducted to compare the efficacy of the different surgical techniques available for IIH treatment. Funding source No external funding was secured for this study. Financial disclosure The authors have no financial relationships relevant to this article to disclose. Conflicts of interest The author declares no competing interests. The content of this manuscript, in part or in full, has not been published elsewhere in any form. I, Fahad Alkherayf certify that this manuscript is a unique submission and is not being considered for publication with any other source in any medium. References [1] Brazis PW. Clinical review: the surgical treatment of idiopathic pseudotumour cerebri (idiopathic intracranial hypertension). Cephalalgia 2008;28(12):1361–73. [2] Toma AK, Dherijha M, Kitchen ND, Watkins LD. Use of lumboperitoneal shunts with the Strata NSC valve: a single-center experience. J Neurosurg 2010;113(6):1304–8. [3] Murtagh F, Lehman R. Peritoneal shunts in the management of hydrocephalus. JAMA 1967;202(11):1010–4. [4] Friedman DI, Jacobson DM. Idiopathic intracranial hypertension. J Neuroophthalmol 2004;24(2):138–45. [5] Abubaker K, Ali Z, Raza K, Bolger C, Rawluk D, O’Brien D. Idiopathic intracranial hypertension: lumboperitoneal shunts versus ventriculoperitoneal shunts – case series and literature review. Br J Neurosurg 2011;25(1):94–9. [6] Digre KB, Corbett JJ. Idiopathic intracranial hypertension (pseudotumor cerebri): a reappraisal. Neurologist 2001;7:2–67. [7] Quincke H. Über Meningitis serosa. Sammlung linische Vortra 67. Inn Med 1893;23:655–94. [8] Nonne M. Über Fälle vom Symptomenkomplex Tumor Cerebri mit Ausgang in Heilun (Pseudotumor Cerebri): Über letal verlaufene Fälle von Pseudotumor Cerebri mit Sektionsbefund. Dtsch Z Nervenheilkd 1904;27:169–216. [9] Dandy WE. Intracranial pressure without brain tumor: diagnosis and treatment. Ann Surg 1937;106(4):492–513. [10] Reid AC, Matheson MS, Teasdale G. Volume of the ventricles in benign intracranial hypertension. Lancet 1980;2(8184):7–8. [11] Hingwala DR, Kesavadas C, Thomas B, Kapilamoorthy TR, Sarma PS. Imaging signs in idiopathic intracranial hypertension: are these signs seen in secondary intracranial hypertension too? Ann Indian Acad Neurol 2013;16(2):229–33. [12] Suzuki H, Takanashi J, Kobayashi K, Nagasawa K, Tashima K, Kohno Y. MR imaging of idiopathic intracranial hypertension. AJNR Am J Neuroradiol 2001;22(1):196–9. [13] Brodsky MC, Vaphiades M. Magnetic resonance imaging in pseudotumor cerebri. Ophthalmology 1998;105(9):1686–93.
F. Alkherayf et al. / Clinical Neurology and Neurosurgery 136 (2015) 5–9 [14] Fraser C, Plant GT. The syndrome of pseudotumour cerebri and idiopathic intracranial hypertension. Curr Opin Neurol 2011;24(1):12–7. [15] Binder DK, Horton JC, Lawton MT, McDermott MW. Idiopathic intracranial hypertension. Neurosurgery 2004;54(3):538–51 [discussion 551–552]. [16] Feldon SE. Visual outcomes comparing surgical techniques for management of severe idiopathic intracranial hypertension. Neurosurg Focus 2007;23(5):E6. [17] Spoor TC, McHenry JG. Long-term effectiveness of optic nerve sheath decompression for pseudotumor cerebri. Arch Ophthalmol 1993;111(5):632–5. [18] Wang VY, Barbaro NM, Lawton MT, Pitts L, Kunwar S, Parsa AT, et al. Complications of lumboperitoneal shunts. Neurosurgery 2007;60(6):1045–8 [discussion 1049]. [19] Nadkarni TD, Rekate HL, Wallace D. Concurrent use of a lumboperitoneal shunt with programmable valve and ventricular access device in the treatment of pseudotumor cerebri: review of 40 cases. J Neurosurg Pediatr 2008;2(1):19–24. [20] Chang CC, Kuwana N, Ito S. Management of patients with normal-pressure hydrocephalus by using lumboperitoneal shunt system with the Codman Hakim programmable valve. Neurosurg Focus 1999;7(4):e8.
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[21] Aoki N. Lumboperitoneal shunt: clinical applications, complications, and comparison with ventriculoperitoneal shunt. Neurosurgery 1990;26(6):998–1003 [discussion 1003–1004]. [22] Moza K, McMenomey SO, Delashaw Jr JB. Indications for cerebrospinal fluid drainage and avoidance of complications. Otolaryngol Clin North Am 2005;38(4):577–82. [23] Kay AD, Fisher AJ, O’Kane C, Richards HK, Pickard JD, United Kingdom and Ireland Medos Shunt Audit Group. A clinical audit of the Hakim programmable valve in patients with complex hydrocephalus. Br J Neurosurg 2000;14(6):535–42. [24] McGirt MJ, Woodworth G, Thomas G, Miller N, Williams M, Rigamonti D. Cerebrospinal fluid shunt placement for pseudotumor cerebri-associated intractable headache: predictors of treatment response and an analysis of longterm outcomes. J Neurosurg 2004;101(4):627–32. [25] Selman WR, Spetzler RF, Wilson CB, Grollmus JW. Percutaneous lumboperitoneal shunt: review of 130 cases. Neurosurgery 1980;6(3):255–7.
Contents lists available at ScienceDirect
Clinical Neurology and Neurosurgery journal homepage: www.elsevier.com/locate/clineuro
Management of idiopathic intracranial hypertension with a programmable lumboperitoneal shunt: Early experience Fahad Alkherayf a,b,c,∗,1 , Hussam Abou Al-Shaar d,1 , Michael Awad a,b a
C2 Clinic – Division of Neurosurgery, The Ottawa Hospital, 1053 Carling Avenue, Ottawa, Ontario, Canada Division of Neurosurgery, The University of Ottawa, Ottawa, Canada The Ottawa Hospital Research Institute (OHRI), Ottawa, Canada d College of Medicine, Alfaisal University, Riyadh, Saudi Arabia b c
a r t i c l e
i n f o
Article history: Received 1 April 2015 Received in revised form 11 May 2015 Accepted 13 May 2015 Available online 27 May 2015 Keywords: Idiopathic intracranial hypertension Programmable valve Lumboperitoneal shunt Hydrocephalus Complications
a b s t r a c t Objective: To evaluate the clinical outcomes and complications rate among idiopathic intracranial hypertension (IIH) patients who underwent lumboperitoneal (LP) shunt insertion with a programmable Strata valve. Methods: We retrospectively evaluated patients who underwent LP shunt with a programmable Strata valve insertion at the University of Ottawa Civic Hospital from November 2012 to June 2013. The demographic data, clinical symptoms, opening pressure, pre-operative and post-operative visual fields, neuroimaging, visual acuity, disc status, and complications were recorded and analyzed. Results: Seven female patients with IIH underwent insertion of an LP shunt with a programmable Strata valve. The mean opening pressure was 35.8 cm H2 O. The initial valve setting was 1.5, and four patients required post-operative valve pressure adjustment. All patients showed significant improvement in objective visual testing at follow-up as well as less frequent headaches. None of the patients developed intra- or post-operative complications. Conclusion: LP shunts with programmable Strata valve systems are a potential alternative to conventional LP and programmable ventriculoperitoneal shunt systems as well as optic nerve sheath fenestration, due to their potential in avoiding brain injury, lower failure and complication rates, lower intracranial hypotension incidence, and flexibility in adjusting valve pressure settings post-operatively evading under- and overdrainage complications. They should be considered for the management of IIH instead of early design LP systems and VP shunts. A randomized multi-center trial should be conducted to compare the efficacy of these surgical techniques. © 2015 Elsevier B.V. All rights reserved.
1. Introduction The use of lumboperitoneal (LP) shunts has been well documented as a treatment modality for patients with idiopathic intracranial hypertension (IIH). There are a number of advantages to LP shunts when compared with other treatment modalities for IIH, such as stereotactic ventriculoperitoneal shunts (VP) and optic nerve sheath fenestrations (ONSF). LP shunts avoid intracranial risks, such as cerebral hemorrhage, seizures, and shunt
Abbreviations: IIH, idiopathic intracranial hypertension. ∗ Corresponding author at: C2 Clinic – Division of Neurosurgery, The Ottawa Hospital, 1053 Carling Avenue, Ottawa, Ontario, Canada. Tel.: +1 6137971239. E-mail address: [email protected] (F. Alkherayf). 1 Both the authors contributed equally to this study. http://dx.doi.org/10.1016/j.clineuro.2015.05.018 0303-8467/© 2015 Elsevier B.V. All rights reserved.
malposition. Additionally, LP shunts may be preferable for patients with small ventricles because of the ease of shunt insertion [1,2]. Early designs of LP shunt systems were composed of a valveless silastic tube, and the diversion of cerebrospinal fluid (CSF) is entirely dependent on the resistance and gravity encountered through the silicon catheter. One criticism of LP shunts is the potential development of low-pressure symptoms caused by CSF overdrainage. Therefore, it was necessary to incorporate a valve into the LP shunt system, which was established by Murtagh in 1967 in order to decrease the incidence of such a complication [3]. A limitation of these valves was the fixed pressure setting established at the time of surgery, which may result in under- or overdrainage complications post-operatively, requiring subsequent shunt revision(s). The development of low-pressure symptoms requiring LP shunt revision has been reported to be as high as 25% [4]. However, with the recent advances in modern technology, such as the introduction
6
F. Alkherayf et al. / Clinical Neurology and Neurosurgery 136 (2015) 5–9
Fig. 1. Photographs of the programmable Strata valve (Medtronic, Inc.).
of programmable valves and small lumen peritoneal catheters, the incidence of intracranial hypotension has decreased, and it is now possible to adjust the valve pressure setting post-operatively to avoid symptoms of over- or underdrainage [1,5]. Therefore, the use of these programmable LP shunts has drastically reduced the need for subsequent revision procedures [1,2,4]. Various programmable valve LP shunt systems have been introduced to the market, and each has its advantages and disadvantages. The Strata LP valve (Medtronic, Inc.) incorporates a ball-and-cone pressure valve (Fig. 1). With this shunt, flow control depends on the resistance of the ball and cone and the degree of resistance determines the performance level of the valve. In addition, retrograde flow is prevented by the ball and cone [2]. The valve pressure setting can be adjusted easily using an external magnet to reach the desired pressure setting. Therefore, it is essential to check and adjust the valve pressure setting in patients after the exposure to large magnetic fields like magnetic resonance imaging (MRI). Programmable valves have been used in VP shunts for decades. However, their use in LP shunt procedures is relatively new. Most of the reported literature describes the use of traditional LP shunts in the management of IIH, and there are few reports in the literature describing the use of programmable valve LP shunts in IIH patients. In addition, most of the current literature comparing the efficacy between LP and VP shunt systems does not consider the LP shunts with programmable valves, resulting in an underestimation of this potentially highly effective alternative. In this account, we report our early experience with programmable LP shunts in the management of IIH at the Ottawa Hospital. 2. Methods We performed a retrospective review and analysis of the clinical records of patients who underwent programmable Strata (Medtronic, Inc.) LP shunt placement by the senior author (F.A.) at the Ottawa Hospital between May 2012 and June 2013 with a minimum follow up of one year. Our inclusion criteria included adult patients who were newly diagnosed with IIH (based on modified Dandy criteria (Table 1)) [6] with visual impairment and with an LP opening pressure of 25 cm H2 O or more at the time of presentation. Patients with previous CSF diversion or previous cranial or abdominal surgeries were excluded. The study was approved by Table 1 Modified Dandy criteria for idiopathic intracranial hypertension [6]. Symptoms of elevated intracranial pressure (headache, nausea, vomiting, transient visual obscurations, or papilledema) Absence of localizing signs in neurological examination with the exception of false localizing signs (e.g., abducens or facial nerve palsies) Patient is awake and alert Normal CT/MRI findings without evidence of thrombosis Lumbar puncture opening pressure of >25 cm H2 O and normal biochemical/cytological composition of CSF No other explanation for raised intracranial pressure
the Research Ethic Board at the Ottawa Hospital Research Institute (OHRI). Informed consent was obtained from all patients involved in the study. Patient demographics, including age, gender, diagnosis, clinical symptoms, opening pressure, pre- and post-operative visual acuity, visual fields, disc status, neuroimaging, and intraand post-operative complications were assessed. The initial valve settings and subsequent adjustments were also reviewed. The Strata programmable valve (Medtronic, Inc.) provides the following full range of performance levels (acceptable pressure ranges are given in parentheses): 0.5 setting (0–3 cm H2 O), 1.0 setting (1–6 cm H2 O), 1.5 setting (5.5–11.5 cm H2 O), 2.0 setting (10.5–17 cm H2 O), and 2.5 setting (15.5–22.5 cm H2 O). The valve is composed of a reservoir and proximal and distal occluders that allow for injection, CSF sampling, and proximal or distal flushing. The valve performance level can be verified through the use of a built-in adjustment system or using a radiographic confirmation. The small lumen peritoneal catheter consists of firmer catheter tubing than conventional LP shunts, which reduces the risk of occlusion or kinking. The small inner diameter provides an average flow resistance of 0.1 cm H2 O/cm catheter length at a constant flow rate of 20 ml/h. The flow-limiting properties of the small lumen peritoneal catheter may decrease the risk of overdrainage [2]. The lumbar catheter can reach up to 84 cm in length while the peritoneal catheter can reach up to 120 cm in length. 3. Surgical technique Patients underwent general anesthesia and endotracheal intubation in the lateral decubitus position with routine skin preparation and draping. Three incisions were made, including a 1cm lumbar incision (L3–L4), a 5-cm flank incision, and a transverse abdominal incision. A total of 10–20 cm of the lumbar catheter was inserted into the subarachnoid space using a Tuohy needle, and the placement of the catheter was confirmed via CSF flow. A subcutaneous pouch was fashioned using curved mayo scissors to house the valve. Following the dissection of the abdominal wall layers into the peritoneum, a small lumen peritoneal catheter was inserted and tunneled between the lumbar and abdominal incisions. The lateral incision was used to move the catheter through the subcutaneous pouch. The pre-programmed valve was anchored with the use of sutures. Flow confirmation was obtained and all three incisions were closed in layers. 4. Results Between May 2012 and June 2013, seven female patients underwent placement of an LP shunt with a programmable Strata valve (Medtronic, Inc.) at the Ottawa Hospital (Table 2). The mean patient age was 33.2 years (range 23–46). Data for pre- and post-operative visual acuity, visual fields, and optic disc status are shown in Table 3. One patient (14.3%) failed to attend the follow-up with their ophthalmologist for a postoperative visual assessment.
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Table 2 Patients demographics. Patient
Age
Gender
Urgency
Opening pressure (cm H2 O)
Initial valve pressure setting
Final valve pressure setting
1 2 3 4 5 6 7
33 32 46 34 33 32 23
F F F F F F F
Elective Elective Elective Emergent Elective Elective Elective
42 29 27 27 30 40 >55
1.5 1.5 1.5 1.5 1.5 1.5 1.5
0.5 2 2 1 1.5 1.5 1.5
Table 3 Pre-operative vs. post-operative visual function. Pre-Op VA
Pre-Op VF
Pre-Op disc status
Post-Op VA
Post-Op VF
Post-Op disc status
1
OD: 20/30 OS: 20/25
Papilledema (OU)
OD: 20/25 OS: 20/20
Improved (OU)
Normal (OU)
2
OD: 20/20 OS: 20/150* OU: 20/20 OD: 20/25 OS: 20/30 OD: 20/20 OS: 20/20* OD: 20/20 OS: 20/25* OU: 20/20
Generalized constriction extended from inferior quadrant (OU) Mild loss (OD) Depressed (OS) Normal (OU) Constriction (OU)
Optic atrophy L > R (OU) Mild gliotic changes (nasal surface) (OU) Papilledema (OU)
OD: 20/20 OS: 20/80 OU: 20/20 OD: 20/20 OS: 20/25 OD: 20/20 OS: 20/20* OD: 20/20 OS: 20/20* –
Improved (OU)
Optic atrophy (OU)
Normal (OU) Normal (OU)
Mild gliotic changes (OU) Normal (OU)
Normal (OD) Mild inferior field loss (OS) Normal (OU)
Normal (OU)
3 4 5 6 7
Mildly depressed (OD) Significant reduction (OS) Enlarged blind spot (OU)
Papilledema (OU)
Loss of peripheral vision (OU)
Papilledema (OU)
Papilledema (OU) + Secondary exudate
–
Minimal disc fullness nasally (OU) -
OD, oculus dexter (right eye); OS, oculus sinister (left eye); OU, oculus uterque (bilateral); VA, visual acuity; VF, visual fields; –, no follow-up; *, afferent pupillary defect detected.
The mean opening pressure detected at the initial evaluation was 35.8 cm H2 O (range 26 to >55 cm H2 O). Six out of seven (85.7%) procedures were elective. The valve pressure setting during the operation was set at 1.5. Because of the high intracranial pressure (ICP) encountered among patients with IIH, we elected to start our shunts with this pressure setting with serial patient assessments post-operatively, monitoring for the development of overor underdrainage symptoms, which requires pressure adjustment. The valve pressure was adjusted in 4 patients based on their postoperative symptoms and clinical and radiological findings at 4 week follow-up as indicated in Table 2. No intra- or post-operative complications were noted in our series. All patients demonstrated post-operative improvements in visual function. 5. Discussion IIH is an uncommon condition, defined as elevated intracranial pressure (ICP) without the presence of a brain mass, hydrocephalus, or changes in the cerebrospinal fluid profile [1]. Quincke was the first to describe this condition in 1893 as a meningitis serosa after his observation of patients with elevated ICP in the absence of a brain lesion [7]. In 1904, Nonne described the condition as a pseudotumor cerebri to highlight the high ICP levels commonly observed in these patients mimicking the findings of brain tumors [8]. This condition was further characterized by Walter E. Dandy in 1937 when he outlined the IIH Inclusion Criteria [9]. A diagnosis of IIH is based on excluding other causes of elevated ICP. Dandy’s original criteria were refined by Digre and Corbett in 2001 (Table 1) and are currently used in clinical practice [6]. Imaging techniques can aid in the diagnosis of IIH. Most of our patients demonstrated the typical imaging findings encountered among IIH patients. The ventricular size is typically decreased or normal in computed tomography (CT) scans [10]. Other CT findings have been reported in the literature, including the widening of the optic nerves and empty sella syndrome [11]. MRI may demonstrate flattening of the posterior sclera, empty sella syndrome, tortuosity and dilation of the optic nerves, and slight enhancement of
the optic disc upon contrast administration [12,13]. Moreover, a lumbar puncture should be performed in IIH patients when other modalities have failed to confirm a diagnosis. The management of IIH remains controversial and can be classified into behavioral modifications, medical treatment, or surgical intervention [1,14,15]. Surgical management is essential when behavioral and medical interventions fail to control patients’ symptoms [1,14,15]. LP and VP shunting, venous sinus stenting, and ONSF are potential surgical therapeutic modalities, with VP and LP shunts being the most commonly used for the management of IIH [1,15]. ONSF and sinus stenting are not typically the first line of surgical treatment and are generally considered only when CSF diversion fails to relieve patients’ symptoms [16,17]. Studies have demonstrated that ONSF can prevent further deterioration of visual function with moderate efficacy in the treatment of papilledema in IIH patients [16]. Nonetheless, a great number of patients who underwent ONSF had a recurrence of symptoms within one year of the procedure, indicating high failure rates [15,17]. According to Spoor et al., only 75% of ONSFs remain functional 6 months after surgery. This value decreased to 66% at 12 months, 55% at 36 months, 38% at 60 months, and 16% at 72 months [17]. Typically, patients with IIH have small ventricles making the placement of the VP shunt catheter challenging, with an increased risk of shunt malfunctions and/or intracranial injuries. Additionally, non-programmable VP shunts are typically associated with over- or underdrainage of CSF leading to shunt malfunction. The use of programmable VP shunts with neuronavigation has helped to reduce the incidence of these complications [18–21]; however, they remain the primary challenge that lead to shunt malfunction. Recent studies have shown a failure rate of nearly 14% in patients managed with VP shunts [5]. VP shunts also carry the risk of intracranial infection; the rate of infection is variable in the literature, with a rate of 4–7% reported in many studies [22]. LP shunting is an alternative method for the treatment of IIH patients. It avoids the risk of intracranial injuries. However, the increased risk of developing acquired Chiari malformation is one of the major side effects of LP shunting. This complication is most
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likely related to the unregulated CSF flow through the standard LP shunts [18–21]. Additionally, standard LP shunts are associated with high failure rates, which can reach up to 11% [5]. Since the establishments of LP shunt systems with valves in 1967, various refinements have been attempted to allow noninvasive post-operative valve pressure adjustments. The Codman Hakim programmable valve was one of the first systems employed to allow such adjustment. The Codman Hakim programmable valve is a differential pressure valve that utilizes digitally-coded magnetic impulses to position a magnetically driven rotor regulating the preload of a flat spring that rests on a ruby ball valve. The opening pressure of the valve is programmed in the range 3–20 cm H2 O [23]. However, CSF overdrainage due to sudden increase in hydrostatic pressure and the valve’s tendency to rotate in the soft tissues of the abdomen were the major limitations of that programmable valve system. Therefore, it was essential to add a flat-bottomed stage to prevent the valve from rotation and a Siphonguard add-on device to respond to rapid changes in hydrostatic pressure [19]. The development of the new LP shunt with a programmable Strata valve (Medtronic, Inc.) system may have the same advantages as the programmable VP shunt without having the intracranial complications. It also has the advantages of the standard LP shunt in addition to decreasing the risk of developing the acquired Chiari malformation. The literature suggests that 95% of patients experience resolution of headaches and up to 100% experience improvement of their symptoms after programmable LP shunt placement [18,24]. Low-pressure symptoms are a common complication reported in patients undergoing traditional LP valve insertions; however, two studies found that these symptoms were reversible with programmable valves. Additionally, acquired Chiari malformation was not observed in any of those patients [18–20]. Other complications associated with LP shunting including shunt obstruction, migration, malposition, infection, arachnoiditis, scoliosis, and radiculopathy have been reported in the literature [18,25]. None of our patients developed acquired Chiari malformation or any of the other complications after programmable LP shunt insertion. In our series, all patients demonstrated objective post-operative improvements in their visual symptoms as well as less frequent headaches. These results are comparable to a previous series by Toma et al., which demonstrated a resolution of visual symptoms in 13/15 (87%) patients who underwent programmable valve placement [2]. In our small series, we elected to start our shunt setting at 1.5 with continuous assessment of patient symptoms post-operatively. Because of the high ICP in IIH patients and based on our data, we recommend 1.5 as a suitable starting setting for IIH patients. We believe that this initial pressure setting is advisable in most patients to avoid post-operative under- and overdrainage complications. However, in the presence of under- or overdrainage complications, LP shunts with programmable Strata valves (Medtronic, Inc.) allow for flexible valve pressure setting adjustment post-operatively. In our cohort, 4 patients required post-operative pressure adjustment based on their post-operative symptoms and clinical and radiological findings. Based on our results, we believe that this programmable LP shunt system is a potential alternative for treating patients with IIH due to brain tissue avoidance and low long-term failure rates. It may also decrease the risk of developing acquired Chiari malformation and low-pressure symptoms. In our study, none of the patients developed intra- and/or post-operative complications or shunt failure. The retrospective nature of our study, the small sample size, the relatively short follow-up period, and the lack of a VP comparison group are the main limitations implicated in this study. However, our study highlights the effectiveness of LP shunt with
a programmable Strata valve (Medtronic, Inc.) in managing IIH patients; it also sheds light on this new modality to be considered in those patients. In addition, our study sets the basis for future prospective randomized multi-center clinical trials to compare this programmable LP shunt system with other IIH treatment modalities. 6. Conclusion LP shunting with a programmable Strata valve (Medtronic, Inc.) system is a promising surgical modality that improves the symptoms of IIH patients and may have fewer complications in comparison to the conventional LP and programmable VP shunt systems due to its potential in evading brain injury, its lower failure and complication rates, lower intracranial hypotension incidence, and flexibility in adjusting the valve pressure settings post-operatively to avoid under- and overdrainage complications. A prospective randomized multicenter clinical trial should be conducted to compare the efficacy of the different surgical techniques available for IIH treatment. Funding source No external funding was secured for this study. Financial disclosure The authors have no financial relationships relevant to this article to disclose. Conflicts of interest The author declares no competing interests. The content of this manuscript, in part or in full, has not been published elsewhere in any form. I, Fahad Alkherayf certify that this manuscript is a unique submission and is not being considered for publication with any other source in any medium. References [1] Brazis PW. Clinical review: the surgical treatment of idiopathic pseudotumour cerebri (idiopathic intracranial hypertension). Cephalalgia 2008;28(12):1361–73. [2] Toma AK, Dherijha M, Kitchen ND, Watkins LD. Use of lumboperitoneal shunts with the Strata NSC valve: a single-center experience. J Neurosurg 2010;113(6):1304–8. [3] Murtagh F, Lehman R. Peritoneal shunts in the management of hydrocephalus. JAMA 1967;202(11):1010–4. [4] Friedman DI, Jacobson DM. Idiopathic intracranial hypertension. J Neuroophthalmol 2004;24(2):138–45. [5] Abubaker K, Ali Z, Raza K, Bolger C, Rawluk D, O’Brien D. Idiopathic intracranial hypertension: lumboperitoneal shunts versus ventriculoperitoneal shunts – case series and literature review. Br J Neurosurg 2011;25(1):94–9. [6] Digre KB, Corbett JJ. Idiopathic intracranial hypertension (pseudotumor cerebri): a reappraisal. Neurologist 2001;7:2–67. [7] Quincke H. Über Meningitis serosa. Sammlung linische Vortra 67. Inn Med 1893;23:655–94. [8] Nonne M. Über Fälle vom Symptomenkomplex Tumor Cerebri mit Ausgang in Heilun (Pseudotumor Cerebri): Über letal verlaufene Fälle von Pseudotumor Cerebri mit Sektionsbefund. Dtsch Z Nervenheilkd 1904;27:169–216. [9] Dandy WE. Intracranial pressure without brain tumor: diagnosis and treatment. Ann Surg 1937;106(4):492–513. [10] Reid AC, Matheson MS, Teasdale G. Volume of the ventricles in benign intracranial hypertension. Lancet 1980;2(8184):7–8. [11] Hingwala DR, Kesavadas C, Thomas B, Kapilamoorthy TR, Sarma PS. Imaging signs in idiopathic intracranial hypertension: are these signs seen in secondary intracranial hypertension too? Ann Indian Acad Neurol 2013;16(2):229–33. [12] Suzuki H, Takanashi J, Kobayashi K, Nagasawa K, Tashima K, Kohno Y. MR imaging of idiopathic intracranial hypertension. AJNR Am J Neuroradiol 2001;22(1):196–9. [13] Brodsky MC, Vaphiades M. Magnetic resonance imaging in pseudotumor cerebri. Ophthalmology 1998;105(9):1686–93.
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