Epifrpsiu, 33(5):829-835, 1992 Raven Press, Ltd., N e w York 0 International League Against Epilepsy
Nonconvulsive Status Epilepticus in Adults: Thirty-Two Consecutive Patients from a General Hospital Population Torbjorn Tornson, Ulla Lindbom, and Bengt Y. Nilsson Departments of Neurology and Clinical Neurophysiology, Karolinska Institutet, Siider Hospital, Stockholm, Sweden
Summary: We studied all adult patients who between 1984 and 1989 were initially diagnosed at our hospital as having nonconvulsive status epilepticus. Thirty-two patients fulfilled the criteria, which included ictal EEG recordings. The annual incidence was 1.5 in 100,000 inhabitants. The median age at onset of status was 51 years. Ten patients had status as their first epileptic manifestation, but most patients had a previous history of epilepsy. Median duration of epilepsy at onset of status was 4 years. Fourteen patients had focal ictal seizure activity on EEG and thus met the criteria for complex partial status.
Eighteen patients had generalized seizure activity on EEG, but only 6 of these had a history of absence epilepsy or juvenile myoclonic epilepsy. None had LennoxGastaut syndrome. The clinical features of status in the remaining 12 patients were in some respects similar to those of the patients with complex partial status. We hypothesize that the EEG seizure activity in these patients may have been generalized from an initial focus. Key Words: Status epilepticus-Nonconvulsive status epilepticus-Complex partial status epilepticus-Absence status epilepticus-Petit ma1 status epilepticus-Adult.
Nonconvulsive status epilepticus is divided into two main subgroups, generalized nonconvulsive status and complex partial status. Generalized nonconvulsive status has been described by various terms (spike wave stupor, epilepsia minoris continua, minor epileptic status, epileptic twilight state, petit ma1 status, and absence status) but may in a strict sense be considered the status form of absence seizures. Gastaut (1983) suggested that the term absence status be used for all forms of nonconvulsive generalized status and that these may be subdivided into typical and atypical absence status. Typical absence status would be the status form of childhood absence epilepsy and be accompanied by rhythmic 3-Hz spike wave discharges. Atypical absence status would appear in patients with atypical absence as part of an epileptic syndrome such as Lennox-Gastaut and be associated with more variable EEG patterns. Several clinical observations indicate, however, that the concept of absence status is poorly defined and covers a large spectrum of varied electroclinical conditions with uncertain boundaries, particularly in adults (Geier, 1978; Porter and Penry, 1983; Fujiwara et al., 1988).
Whereas epilepsy with complex partial seizures is by far more common than absence epilepsy, the number of reported patients with complex partial status are few as compared with patients with absence status (Ballenger et al., 1983; Porter and Penry, 1983). Absence epilepsy occurs in children, but absence status frequently presents de novo in adult patients (Schwartz and Scott, 1971; Berkovic and Bladin, 1982; Ballenger et al., 1983; Bateman et al., 1983; Porter and Penry, 1983). When absence status in adults is compared with absence status in children, differences are evident in both clinical and EEG manifestations (Fujiwara et al., 1988). Cases of adult absence status have been successfully treated with phenytoin (PHT) and phenobarbital (PB), drugs devoid of effect on absence seizures (Ellis and Lee, 1978). Antiabsence drugs have shown no prophylactic effect in many adults with absence status (Fujiwara et al., 1988). These observations have led some investigators to suggest that nonconvulsive generalized status in later life is an entity distinct from absence status of early onset (Lee, 1985). Others have suggested that cases classified as absence status may actually be complex partial status in which the initial focal ictal discharges in the EEG have become generalized (Roger et al., 1974; Markand et al., 1978). This would explain some of the apparently conflicting previous observations.
Received September 1991 ; revision accepted January 1992. Address correspondence and reprint requests to Dr. T. Tomson at Department of Neurology, Soder Hospital S-118 83 Stockholm, Sweden.
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T . TOMSON ET AL.
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Most previous studies of nonconvulsive status derive from epilepsy centers and thus carry the inherent risk of referral bias. It is difficult to draw general conclusions about the frequency of nonconvulsive status, the relative frequencies of its subtypes, and the clinical and EEG features of status from such studies, but population-based studies are rare (Dunne et al., 1987). We previously reported 10 consecutive adult patients with nonconvulsive status epilepticus diagnosed at a general hospital (Tomson et al., 1986). We were impressed by the high proportion of patients with complex partial status ( 5 of 10). The patient material has now been extended by inclusion of all patients with nonconvulsive status epilepticus initially diagnosed between 1984 and 1989. This study, based on a general hospital population, is a prospective evaluation of the clinical characteristics of the nonconvulsive status epilepticus in 32 adult patients. PATIENTS AND METHODS
The Department of Neurology at Soder Hospital provides adult neurologic service to 350,000 inhabitants aged > 15 years in an urban area of Stockholm County. It is the only neurology department in the area. All patients aged 215 years who between 1984 and 1989 were initially diagnosed at this hospital as having nonconvulsive status epilepticus were included in the study and followed clinically until March 1991. Nonconvulsive status epilepticus was defined as a state of impaired consciousness or responsiveness without convulsions lasting at least 60 min. An ictal EEG showing continuous or almost continuous seizure activity was required for inclusion. Ictal EEG recordings were performed on 16channel Grass (Grass Instrument Co., Quincy, MA, U.S.A.) or Nihon-Kohden (Tokyo, Japan) EEG machines with 21 electrodes placed according to the International 10-20 system. The clinical features of status were documented by clinical examination and repeated testing of consciousness and responsiveness performed by a neurologist. The procedure was adjusted according to the state of the individual patient. The seizures and epileptic syndromes of the patients were classified according to the proposal of the International League Against Epilepsy (Commission, 1981, 1989).
before age 15 years. The age at onset of status ranged from 10 to 81 years (median 51 years) (Fig. 1). Nonconvulsive status was the first epileptic manifestation in 10 patients and has remained the only manifestation in 8. Most patients had a previous history of epilepsy. The median duration of epilepsy at onset of status was 4 years (range 0-72 years). Individual duration of epilepsy is plotted against age at onset of status in Fig. 2. Duration of status episodes ranged from 1 Y2 h to 2 weeks (median 13 h). On follow-up, 1-7 years after diagnosis, 1 1 patients had had a single episode of nonconvulsive status, 21 patients had experienced recurrent episodes, 9 had had between two and five episodes, and 12 patients had had more than five episodes. Nine of the patients died during the follow-up period. One was the youngest patient, who at age 23 years died in a sudden, unexplained death. Another died of malignant glioma. The other 7 patients died of various causes unrelated to the epilepsy, such as myocardial or cerebral infarction. All had late (after age 60 years) onset of status epilepticus. Factors that may have precipitated status are shown in Table 1. Fourteen patients had impaired consciousness and focal EEG seizure activity during status and thus met the criteria for complex partial status. In 1 , the focal character of the EEG activity was apparent at first in connection with termination of status. The focus appeared to be frontal in 8 patients, temporal in 5 , and indeterminate in 1 patient. Eighteen patients had generalized EEG seizure activity. Only 4 of these had continuous rhythmic spike waves of 3 Hz. Eight patients showed generalized spike waves with a frequency
Nonconvulsive Status Epilepticus in Adults: Thirty-Two Consecutive Patients from a General Hospital Population Torbjorn Tornson, Ulla Lindbom, and Bengt Y. Nilsson Departments of Neurology and Clinical Neurophysiology, Karolinska Institutet, Siider Hospital, Stockholm, Sweden
Summary: We studied all adult patients who between 1984 and 1989 were initially diagnosed at our hospital as having nonconvulsive status epilepticus. Thirty-two patients fulfilled the criteria, which included ictal EEG recordings. The annual incidence was 1.5 in 100,000 inhabitants. The median age at onset of status was 51 years. Ten patients had status as their first epileptic manifestation, but most patients had a previous history of epilepsy. Median duration of epilepsy at onset of status was 4 years. Fourteen patients had focal ictal seizure activity on EEG and thus met the criteria for complex partial status.
Eighteen patients had generalized seizure activity on EEG, but only 6 of these had a history of absence epilepsy or juvenile myoclonic epilepsy. None had LennoxGastaut syndrome. The clinical features of status in the remaining 12 patients were in some respects similar to those of the patients with complex partial status. We hypothesize that the EEG seizure activity in these patients may have been generalized from an initial focus. Key Words: Status epilepticus-Nonconvulsive status epilepticus-Complex partial status epilepticus-Absence status epilepticus-Petit ma1 status epilepticus-Adult.
Nonconvulsive status epilepticus is divided into two main subgroups, generalized nonconvulsive status and complex partial status. Generalized nonconvulsive status has been described by various terms (spike wave stupor, epilepsia minoris continua, minor epileptic status, epileptic twilight state, petit ma1 status, and absence status) but may in a strict sense be considered the status form of absence seizures. Gastaut (1983) suggested that the term absence status be used for all forms of nonconvulsive generalized status and that these may be subdivided into typical and atypical absence status. Typical absence status would be the status form of childhood absence epilepsy and be accompanied by rhythmic 3-Hz spike wave discharges. Atypical absence status would appear in patients with atypical absence as part of an epileptic syndrome such as Lennox-Gastaut and be associated with more variable EEG patterns. Several clinical observations indicate, however, that the concept of absence status is poorly defined and covers a large spectrum of varied electroclinical conditions with uncertain boundaries, particularly in adults (Geier, 1978; Porter and Penry, 1983; Fujiwara et al., 1988).
Whereas epilepsy with complex partial seizures is by far more common than absence epilepsy, the number of reported patients with complex partial status are few as compared with patients with absence status (Ballenger et al., 1983; Porter and Penry, 1983). Absence epilepsy occurs in children, but absence status frequently presents de novo in adult patients (Schwartz and Scott, 1971; Berkovic and Bladin, 1982; Ballenger et al., 1983; Bateman et al., 1983; Porter and Penry, 1983). When absence status in adults is compared with absence status in children, differences are evident in both clinical and EEG manifestations (Fujiwara et al., 1988). Cases of adult absence status have been successfully treated with phenytoin (PHT) and phenobarbital (PB), drugs devoid of effect on absence seizures (Ellis and Lee, 1978). Antiabsence drugs have shown no prophylactic effect in many adults with absence status (Fujiwara et al., 1988). These observations have led some investigators to suggest that nonconvulsive generalized status in later life is an entity distinct from absence status of early onset (Lee, 1985). Others have suggested that cases classified as absence status may actually be complex partial status in which the initial focal ictal discharges in the EEG have become generalized (Roger et al., 1974; Markand et al., 1978). This would explain some of the apparently conflicting previous observations.
Received September 1991 ; revision accepted January 1992. Address correspondence and reprint requests to Dr. T. Tomson at Department of Neurology, Soder Hospital S-118 83 Stockholm, Sweden.
829
T . TOMSON ET AL.
(330
Most previous studies of nonconvulsive status derive from epilepsy centers and thus carry the inherent risk of referral bias. It is difficult to draw general conclusions about the frequency of nonconvulsive status, the relative frequencies of its subtypes, and the clinical and EEG features of status from such studies, but population-based studies are rare (Dunne et al., 1987). We previously reported 10 consecutive adult patients with nonconvulsive status epilepticus diagnosed at a general hospital (Tomson et al., 1986). We were impressed by the high proportion of patients with complex partial status ( 5 of 10). The patient material has now been extended by inclusion of all patients with nonconvulsive status epilepticus initially diagnosed between 1984 and 1989. This study, based on a general hospital population, is a prospective evaluation of the clinical characteristics of the nonconvulsive status epilepticus in 32 adult patients. PATIENTS AND METHODS
The Department of Neurology at Soder Hospital provides adult neurologic service to 350,000 inhabitants aged > 15 years in an urban area of Stockholm County. It is the only neurology department in the area. All patients aged 215 years who between 1984 and 1989 were initially diagnosed at this hospital as having nonconvulsive status epilepticus were included in the study and followed clinically until March 1991. Nonconvulsive status epilepticus was defined as a state of impaired consciousness or responsiveness without convulsions lasting at least 60 min. An ictal EEG showing continuous or almost continuous seizure activity was required for inclusion. Ictal EEG recordings were performed on 16channel Grass (Grass Instrument Co., Quincy, MA, U.S.A.) or Nihon-Kohden (Tokyo, Japan) EEG machines with 21 electrodes placed according to the International 10-20 system. The clinical features of status were documented by clinical examination and repeated testing of consciousness and responsiveness performed by a neurologist. The procedure was adjusted according to the state of the individual patient. The seizures and epileptic syndromes of the patients were classified according to the proposal of the International League Against Epilepsy (Commission, 1981, 1989).
before age 15 years. The age at onset of status ranged from 10 to 81 years (median 51 years) (Fig. 1). Nonconvulsive status was the first epileptic manifestation in 10 patients and has remained the only manifestation in 8. Most patients had a previous history of epilepsy. The median duration of epilepsy at onset of status was 4 years (range 0-72 years). Individual duration of epilepsy is plotted against age at onset of status in Fig. 2. Duration of status episodes ranged from 1 Y2 h to 2 weeks (median 13 h). On follow-up, 1-7 years after diagnosis, 1 1 patients had had a single episode of nonconvulsive status, 21 patients had experienced recurrent episodes, 9 had had between two and five episodes, and 12 patients had had more than five episodes. Nine of the patients died during the follow-up period. One was the youngest patient, who at age 23 years died in a sudden, unexplained death. Another died of malignant glioma. The other 7 patients died of various causes unrelated to the epilepsy, such as myocardial or cerebral infarction. All had late (after age 60 years) onset of status epilepticus. Factors that may have precipitated status are shown in Table 1. Fourteen patients had impaired consciousness and focal EEG seizure activity during status and thus met the criteria for complex partial status. In 1 , the focal character of the EEG activity was apparent at first in connection with termination of status. The focus appeared to be frontal in 8 patients, temporal in 5 , and indeterminate in 1 patient. Eighteen patients had generalized EEG seizure activity. Only 4 of these had continuous rhythmic spike waves of 3 Hz. Eight patients showed generalized spike waves with a frequency
