Postoperative Epilepsy Research Articles

Postoperative seizures: epidemiology, pathology, and prophylaxis.

The risk of epileptic seizures after craniotomy is extremely important but the incidence of postoperative epilepsy varies greatly, depending on the patient's conditions such as primary diseases, severity of surgical insult, and pre-existing epilepsy. Animal studies suggest that neurosurgical insults lead to seizures by two different mechanisms: One mechanism is mediated by free radical generation and the other by impaired ion balance across the cell membrane caused by ischemia or hypoxia. Conventional antiepileptic agents such as phenytoin, phenobarbital, carbamazepine, and valproic acid are promising for the prevention of early seizures, but the effect in preventing postoperative epilepsy is still controversial. Studies on the prophylactic effect of newer antiepileptic agents in craniotomized patients were very limited. Zonisamide, an antiepileptic agent with antiepileptogenic, free radical scavenging and neuroprotective actions in experimental animals, showed promising effects against postoperative epilepsy in a randomized double blind controlled trial. Prophylactic treatment for craniotomized patients significantly prevented the development of partial seizures during the follow-up period. Most recent studies have not supported the prophylactic use of antiepileptic agents in craniotomized patients, but further studies are required.

Transcortical or transcallosal approach to ventricle-associated lesions: a clinical study on the prognostic role of surgical approach.

Most entities in and around the anterior two-thirds of the supratentorial ventricles can be reached via transcortical or transcallosal approach. This study examined the effect of surgical approach on the postoperative neurological outcome. Thirty-eight patients with intra- and periventricular supratentorial lesions were operated on by either frontal transcortical or anterior transcallosal approach. Postoperative diencephalic damage occurred in 22% of patients in the transcortical group and in 36% in the transcallosal group; transient mutism was virtually equivalent in the two groups. Postoperative epilepsy (26%) and subdural fluid collections (30%) occurred only in the transcortical group. The incidence of postoperative hemiparesis was higher in the transcallosal group. There was a high correlation between postoperative Glasgow Outcome Score of 5 and preoperative severity of neurological disease but no correlation between postoperative Glasgow Outcome Score of 5 and location of the lesion or between postoperative clinical course and surgical approach. Surgical outcome of ventricle-associated lesions depends mainly on the severity of preoperative symptoms and not on surgical approach. Additionally, the incidence of postoperative seizures and subdural fluid collections after transcortical surgery is high.

Tratamiento antiepiléptico profiláctico de las agresiones cerebrales

On the occasion of the First Congress of the Spanish Anti Epilepsy League we had reviewed the use of antiepileptic drugs for preventing postoperative and posttraumatic seizures.Two specific causes of epilepsy are particularly relevant to neurosurgical practice; postoperative and posttraumatic epilepsy. After reviewing the seizures arising after craniotomy for supratentorial conditions such as vascular malformations (aneurysms and arteriovenous malformations), cerebral tumours and supratentorial abscesses and empyemas, we discuss the different types of posttraumatic epilepsy and the risk factors. The pathogenesis of tumour associated epilepsy and the pathophysiological events initiating posttraumatic epilepsy are described. The use of prophylactic antiepileptic drugs is only justified in cases with several risk factors capable to develop seizures.As no treatments have yet been shown to be effective in preventing the development of epileptic seizures, additional trials are likely to be necessary.

Interactive image-guided transcallosal microsurgery for anterior third ventricular cysts.

Although the treatment of colloid cysts remains controversial, high viscosity and small volume are poor prognostic indicators for successful burr hole aspiration and cortical incision via craniotomy may be associated with postoperative epilepsy. The anterior transcallosal approach provides a direct and adequate pathway to the lateral ventricles, where the foramen of Monro serves as a natural entrance into the anterior third ventricle, especially when the foramen is dilated by a lesion. When the midsuperior portion of the IIIrd ventricle cannot be reached, the interforniceal or the subchoroidal exposures have been advocated. Stereotactic techniques contribute to a minimal invasive approach and reduce morbidity. Nine patients harbouring anterior third ventricular cysts (seven colloids and two intrinsic craniopharyngiomas) underwent anterior transcallosal microsurgical excision assisted by an interactive infrared-based image guided system (EasyGuide, Neuro, Philips). There were 4 men and 5 women ranging in age from 15 to 42 years (mean 28.5). Transcallosal transforaminal (5 cases) or interforniceal (4 cases) approaches allowed total excision in eight patients and subtotal in one. Postoperative morbidity included a case of transient hemiparesis and a case of transient short-term memory disturbances; both resolved in the first months. Mortality was zero. Particular advantages of the method were accurate trajectory and position of callosotomy incision determination, visualisation and avoidance of superior saggital sinus, retraction of bridging veins and the often variable pericallosal arteries, spatial orientation within the ventricular system, and identification of the periventricular anatomical structures.

Intracranial meningiomas and epilepsy: incidence, prognosis and influencing factors

In a retrospective study of a consecutive series of 222 surgically treated meningiomas, it was found that 26.6% of the patients presented epilepsy as their initial symptom. In this group, surgical excision of the intracranial meningiomas stopped the epilepsy in about 62.7% of the patients. But approximately one-fifth of the patients with intracranial meningiomas and no history of preoperative epilepsy developed new onset postoperative seizures. Of the patients with early onset of postoperative epilepsy, epilepsy appeared in 66.7% within first 48 h after surgery. Of the patients with postoperative epilepsy, 71.2% were seizure-free following 1 year of anticonvulsant therapy. Regarding preoperative existing factors, intracranial meningiomas located at supratentorium, convexity, and with evidence of or severe peritumoral edema significantly contributed to preoperative epilepsy. And in patients with preoperative epilepsy, those tumors with evidence of or severe perifocal edema and cerebral edema at the operative site were significantly more likely to suffer from postoperative epilepsy.

開頭術後てんかん発作に対するzonisamideの臨床効果 : 二重盲検群間比較試験法による検討

開頭術後てんかん発作に対するzonisamideの臨床効果 : 二重盲検群間比較試験法による検討

Epilepsy in shunt-treated hydrocephalus.

Although epilepsy is commonly associated with shunt-treated hydrocephalus, its relation to the shunting procedure and the criteria identifying postoperative epilepsy remain controversial. Of 283 patients shunted at Würzburg University Hospital over a 24-year period (1970 to 1994), 182 were followed up for a minimum of 1 year after shunt insertion and entered the study. The data were analyzed retrospectively in 1995 and 1996. Epilepsy was analyzed in relation to the etiology of hydrocephalus, functional status, time and site of shunt insertion, onset of seizures and seizure type, EEG changes, sex, shunt systems, and shunt revisions. Of the 182 patients studied, 37 (20%) developed epilepsy. The incidence of epilepsy varied according to the etiology of hydrocephalus: posthemorrhagic (5%), postinfectious (4%), connatal/miscellaneous/unknown (3%), myelomeningocele (2%), tumor/arachnoidal cyst/aqueduct stenosis (0%). Early shunting and poor functional status was associated with a higher risk for epilepsy. Epilepsy was not influenced by sex, shunt systems, or number of shunt revisions. Twenty-two (12%) of 182 patients developed epilepsy (generalized N=13, focal N=9) after intracranial shunting. Focal EEG abnormalities (N=16) were located mainly at the anatomical site of the shunt (N=14), but only three patients (2%) presented with focal seizures contralateral and focal EEG abnormalities ipsilateral to the site of the shunt. The presence of epilepsy was determined by the etiology of hydrocephalus rather than by surgical intervention. The incidence of postoperative epilepsy (12%) was low. Onset of epilepsy, clinical presentation of seizures, and EEG changes did not appear to be valid criteria for identifying shunt-related epilepsy. Thus, epilepsy as a complication of intracranial shunting might be overestimated in the literature.

病棟活動の質的向上の試み 第４報 脳腫よう摘出術後のゾニサミドの血中濃度と術後けいれん発作の予防効果

Delayed onset epilepsy after intracranial surgery has been observed in our neurosurgery ward. We performed a clinical pharmacy service using therapeutic drug monitoring (TDM) during treatment with zonisamide (ZNS) for a 46-year-old woman who had a high risk of postoperative epilepsy. We administered medication of ZNS 200 mg/day a week before surgery and assessed its prophylactic efficacy against postoperative late epilepsy. On the fourth day of therapy, the plasma concentrations of ZNS measured using HPLC just before and 2 hours after drug administration were 9.3 and 12.3μg/ml, respectively. On the seventh day of therapy, the plasma concentrations just before and immediately after surgery were 10.6 and 7.0μg/ml, respectively. On the second and third days after surgery, transient sensory seizures developed and the plasma concentrations were 9.0 and 11.0μg/ml, respectively. Subsequently the dosage of ZNS was increased to 300 mg/day. On the sixth and tenth days after surgery, similar seizures again developed and the plasma concentrations at that time were 15.2 and 15.6μg/ml, respectively. Therefore, the dosage of ZNS was further increased to 400 mg/day. On the twenty-fourth day after surgery, the plasma concentration was 21.0μg/m1 and no further seizures were subsequently noted. The patient was discharged one month after the operation with no complications.Prophylactic anticonvulsant therapy after intracranial surgery remains controversial, but our observations suggested that ZNS may thus be useful for preventing postoperative late epilepsy. TDM was thus found to provide important pharmacokinetic information to effectively control the medication dosage in patients at high risk for developing postoperative epilepsy.

Intracranial Arachnoid Cysts: Treatment Alternatives and Outcome in A Series of 25 Patients

A series of 25 patients with intracranial arachnoid cysts is analyzed retrospectively. There were 14 males and 11 females ranging in age between a few days and 58 (mean 10) years. Seventy-six percent of patients were children below the age of 15 years. Most of the patients presented with symptoms and signs of long-standing raised intracranial pressure, while localizing signs were rather uncommon. The clinical manifestations were often mild relative to the large size of the cyst. Associated hydrocephalus was present in three patients: one with suprasellar cyst and two with posterior fossa cysts. Seven patients with mild symptoms and small cysts were treated conservatively, while the remaining 18 patients underwent surgical treatment. The initial surgical procedure consisted of craniotomy and fenestration of the cyst in three patients, and cystoperitoneal shunting in the other 15. Of the three patients who underwent craniotomy, one improved postoperatively, while the remaining two developed complications consisting of wound infection and postoperative epilepsy in one and permanent severe neurological deficit in the other. In contrast, six of the 15 cysts treated by shunting resolved completely, eight were smaller, and one remained unchanged. Radiological regression of the cyst after shunting was associated with various degrees of clinical improvement in 13 patients (87%). Two (13%) of 15 shunted patients developed complications in the early postoperative period, consisting of wound infection in one and early shunt failure in the other. Three patients (20%) with shunts had late complications during the follow-up period, consisting of recurrent shunt failure in the first, subdural hematoma in the second, and perforation of the peritoneal catheter into the hepatic bile ducts in the third. These findings, as well as recent data from the literature, suggest that in the management of intracranial arachnoid cysts, cystoperitoneal shunting was more effective and had fewer serious complications than craniotomy and cyst fenestration, and therefore, it is recommended as the treatment of first choice.

Short-term perioperative anticonvulsant prophylaxis for the surgical treatment of low-risk patients with intracranial aneurysms.

The long-term use of anticonvulsant medication to prevent postoperative seizures in patients with aneurysms has been accepted medical practice for many years. The low incidence of seizures in more recent aneurysm series makes it appropriate to re-evaluate the use of prophylactic anticonvulsants to prevent postoperative epilepsy, especially in patients at low risk of seizure disorders. On the basis of preoperative presentation, we categorized 387 of the 420 craniotomies for aneurysms over a 4-year period to be at low risk of seizure. Postoperative anticonvulsant medication in this group was restricted to an average of 3 days. A retrospective analysis of the incidence of early postoperative seizures and late postoperative seizure disorders was performed in the populations of patients with ruptured aneurysms and with unruptured aneurysms with an average follow-up of 2.4 years. The overall seizure rate in the study group was 5.4%. Patients with ruptured aneurysms had an early postoperative seizure rate of 1.5% and a long-term seizure disorder rate of 3.0%. Early and long-term seizure rates for unruptured aneurysms were 2.6 and 4.4%, respectively. No patients who had early seizures went on to develop epilepsy, and all seizure disorders were well controlled once anticonvulsants were begun. These data support the idea that anticonvulsant medication may be safely restricted to the immediate perioperative period for most patients with aneurysms.

Incidence of Postoperative Epilepsy in Children following Subfrontal Craniotomy for Tumor

Thirty-one children who underwent 36 subfrontal craniotomies were retrospectively studied to determine the incidence of postoperative epilepsy and the effectiveness of antiepileptic drugs for seizure prophylaxis. The incidence of postoperative epilepsy following a subfrontal craniotomy did not exceed 12% when examined at various time periods during a 3-year postoperative course. Antiepileptic drugs were not warranted to reduce the incidence of postoperative seizures after the 1-month postoperative period and should not be used for long-term prophylactic therapy in children following a subfrontal craniotomy.

Current treatment strategies in selected situations in epilepsy.

Several special situations in the management of epilepsy require specific treatment strategies. Recurrence rates after a single seizure vary between 26 and 71%. Antiepileptic drug (AED) therapy should be initiated after a first seizure only when a definitive diagnosis of epilepsy can be made. Although several AEDs have been shown to be anti-epileptogenic in animal models, no data yet prove the efficacy of any AED in preventing the development of post-traumatic or postoperative epilepsy. Therefore, there is no rational basis for prophylactic treatment with AEDs. The incidence of epilepsy rises dramatically after the age of 50 years. Similtaneously, many physiological changes increase the potential for adverse effects and drug interactions when AEDs are used in the elderly. Careful attention to changing pharmacokinetic parameters is necessary when that group of patients is being managed. Pregnancy also brings about physiological changes that may either increase or decrease the seizure frequency. The risk of fetal malformations is approximately double in children born to mothers with epilepsy compared with children born to nonepileptic mothers. The risk is dose-dependent and increases with the number of AEDs. All AEDs may cause fetal malformations; valproate and carbamazepine increase the risk of spina bifida. Nonetheless, the best AED for a woman who wants to become pregnant is the AED that best controls her seizures, which should be given at the lowest possible effective dose. Discontinuation of AEDs can be considered after 2-4 years of complete seizure control. Most of the risk of relapse occurs within the first 6 months. Status epilepticus (SE) is a medical emergency. The most common form of SE is generalized convulsive status epilepticus, in which the patient may present with either overt or subtle convulsions. Because of the potential for neuronal damage, all electrical as well as clinical seizure activity must be completely stopped for treatment of SE to be considered successful.

Post-Operative Epilepsy Recurrence

Post-operative seizures occurred in 72 patients after resective procedures for epilepsy at The Epilepsy Surgery Program, Departments of Neurology and Neurological Surgery, The Cleveland Clinic Foundation, Cleveland, OH.

Treatment of cerebral arteriovenous malformations with a combination of preoperative embolization and surgery

Forty-nine patients with cerebral arteriovenous malformations (AVMs) were treated with preoperative embolization followed by resection using a microsurgical approach. In 27 patients, the AVM was located in an eloquent area; in 32 patients, the volume of the AVM was over 20 cm3. Preoperatively, flow-directed embolization was performed in 10 patients (28 procedures), selective embolization with threads was performed in 35 patients (46 procedures), and a combination of flow-directed and selective embolization was performed in 4 patients (12 procedures). The percentage of reduction of the AVM volume averaged 36% after embolization. Five minor complications (transient neurological deficits, in 2 cases associated with ischemic areas on the CT scan) were observed after embolization. The interval between the last embolization and surgery was as follows: within 10 days in 7 patients; between 11 and 20 days in 3 patients; between 21 and 30 days in 10 patients; between 31 and 60 days in 11 patients; and 2 months later in 18 patients. The efficacy of this combined treatment (embolization plus surgery) was evaluated by the incidence of hyperemic complications and the clinical outcome. Hyperemic complications occurred more frequently in patients with an AVM volume greater than 20 cm3. When compared with flow-directed embolization, selective embolization was linked with decreased bleeding during surgery; postoperatively, the incidence of cerebral edema was also lower. Clinical outcome was better after selective embolization, with no occurrence of major deficits and no mortality. When the percentage of reduction of the AVM volume after embolization was 40% or more, the incidence of intraoperative hyperemic complications was lower; moreover, new permanent deficits were never observed in patients with this volume reduction. A retrospective clinical comparison of two groups of patients with similar AVM volumes (greater than 20 cm3)--those given combined treatment (n = 32) versus those treated by direct surgery alone (n = 27)--showed that intraoperative bleeding appeared to decrease in patients treated by embolization; the incidence of postoperative hyperemic complications was not different in the two groups. New major deficits and deaths were less frequent in patients treated by embolization (P = 0.05 for the incidence of major deficits); postoperative epilepsy was also less common in these patients. In conclusion, combined treatment with selective preoperative embolization and direct surgery may help the neurosurgeon in the treatment of large, high-flow AVMs, reducing the risks connected with their surgical removal.

Treatment of Cerebral Arteriovenous Malformations with a Combination of Preoperative Embolization and Surgery

Abstract Forty-nine patients with cerebral arteriovenous malformations (AVMs) were treated with preoperative embolization followed by resection using a microsurgical approach. In 27 patients, the AVM was located in an eloquent area; in 32 patients, the volume of the AVM was over 20 cm3. Preoperatively, flow-directed embolization was performed in 10 patients (28 procedures), selective embolization with threads was performed in 35 patients (46 procedures), and a combination of flow-directed and selective embolization was performed in 4 patients (12 procedures). The percentage of reduction of the AVM volume averaged 36% after embolization. Five minor complications (transient neurological deficits, in 2 cases associated with ischemic areas on the CT scan) were observed after embolization. The interval between the last embolization and surgery was as follows: within 10 days in 7 patients; between 11 and 20 days in 3 patients; between 21 and 30 days in 10 patients; between 31 and 60 days in 11 patients; and 2 months later in 18 patients. The efficacy of this combined treatment (embolization plus surgery) was evaluated by the incidence of hyperemic complications and the clinical outcome. Hyperemic complications occurred more frequently in patients with an AVM volume greater than 20 cm3. When compared with flow-directed embolization, selective embolization was linked with decreased bleeding during surgery; postoperatively, the incidence of cerebral edema was also lower. Clinical outcome was better after selective embolization, with no occurrence of major deficits and no mortality. When the percentage of reduction of the AVM volume after embolization was 40% or more, the incidence of intraoperative hyperemic complications was lower; moreover, new permanent deficits were never observed in patients with this volume reduction. A retrospective clinical comparison of two groups of patients with similar AVM volumes (>20 cm3)—those given combined treatment (n = 32) versus those treated by direct surgery alone (n = 27)—showed that intraoperative bleeding appeared to decrease in patients treated by embolization; the incidence of postoperative hyperemic complications was not different in the two groups. New major deficits and deaths were less frequent in patients treated by embolization (P= 0.05 for the incidence of major deficits); postoperative epilepsy was also less common in these patients. In conclusion, combined treatment with selective preoperative embolization and direct surgery may help the neurosurgeon in the treatment of large, high-flow AVMs, reducing the risks connected with their surgical removal. (Neurosurgery 29:358-368, 1991)

Epilepsy in chronic subdural haematoma

Out of 130 patients operated upon for chronic subdural haematoma, 9 presented with epileptic fits before surgery. 5 patients suffered generalized, and 4 partial seizures. The early operative results were very good, and follow-up lasting for at least 3 years revealed that 7 patients were seizure free, and only two of them continued with epileptic seizures. However 7 patients, who did not suffer epilepsy before the evacuation of haematoma developed epilepsy within the first year after surgery. The overall incidence of postoperative epilepsy was 7%. The authors suggest that the capsule of the haematoma plays an important role in the incidence of epilepsy after surgical treatment of chronic subdural haematoma.

Long-term outcome following anterior cerebral artery ligation for ruptured anterior communicating artery aneurysms

The long-term prognosis (15 years) was determined for 17 patients who had undergone anterior cerebral artery (ACA) ligation as the sole treatment for an anterior communicating artery aneurysm. The number of early and late rebleeds was lower than expected from previously ruptured aneurysms. Late ischemia was not a major complication while late postoperative epilepsy occurred in 19% of survivors. In a review of previously published series, ACA ligation appears to have significantly reduced the rates of both early and late rebleeding. This study helps to define the late results of "conservative" operations for ruptured aneurysms.

脳動脈瘤術後の深部脳波異常

Early epilepsy is a well-documented complication after aneurysm operations, but the mechanism is not well clarified. After aneurysm clipping, CSF drainage equipped with electrodes was inserted around aneurysm in 25 cases in which 20 patients were operated on within 48 hours after onset of subarachnoid hemorrhage and 3 during the chronic stage. Two cases had unruptured aneurysms. Both scalp and depth EEGs were continuously monitored for 7 to 14 days after operation. In these 25 cases, anticonvulsant was given in only one case.Three types of EEG abnormalities were recorded. Type A: Spike or sharp wave localized to deep recordings and not observed from scalp EEGs. The peak of spike incidence was day 1 or 2 after operation in cases of less prominent SAH on preoperative CT. In cases of massive SAH, an increase of spike incidence was observed. Type B: Sustained paroxysm localized to deep recordings. This was recorded in 7 cases from day 2 to 13. In 5 cases, prominent SAH was observed on CT. Type C: Secondary generalization of seizure discharges was observed in 2 cases with massive SAH. Epileptiform discharges started from deep recordings. Administration of VPA did not prevent occurrence of type A discharge. These results suggest that early epilepsy after aneurysm operation may originate in the infero-medial part of the frontal or temporal lobe damaged by either SAH per se or surgical manipulation. Possible mechanisms of postoperative epilepsy after aneurysm operation and indication of prophylactic administration of anticonvulsant are in this paper.

Hypertension as a Risk Factor for Epilepsy after Aneurysmal Subarachnoid Hemorrhage and Surgery

Abstract A prospective, consecutive series of 307 patients with aneurysmal subarachnoid hemorrhage ranging from Grades I to V according to the classification of Hunt and Hess on admission were evaluated to determine the incidence of epilepsy 1 to 3 years (mean, 1.4 years) after aneurysmal subarachnoid hemorrhage (SAH) and surgery. Sixty-three patients had died and one patient was lost to follow-up. Twenty-nine patients developed epileptic seizures after the SAH and surgery. The mean time from the SAH to epileptic seizure varied from 0 days (day of the SAH) to 2 years (mean, 6.7 months). The seizures were classified as focal in 9 patients (31%) and as generalized in 20 patients (69%). All patients received anticonvulsant medication after more than one seizure. The risk factors for development of posthemorrhagic/postoperative epilepsy were, in order of importance: a history of hypertension; an infarct on late computed tomographic scan; and the duration of coma after the ictus. Of the 85 patients with histories of hypertension, 17 (20.0%) developed epilepsy. Only 12 (5.4%) of the 222 nonhypertensive patients developed epileptic seizures. The difference between the groups was significant (P =0.0001). Computed tomographic scans were undertaken in 237 patients 1 to 3 years (mean, 1.4 years) after the SAH and surgery. Postoperative epilepsy was significantly associated with infarcts visualized on computed tomographic scan (P = 0.0005).

Hypertension as a risk factor for epilepsy after aneurysmal subarachnoid hemorrhage and surgery

A prospective, consecutive series of 307 patients with aneurysmal subarachnoid hemorrhage ranging from Grades 1 to V according to the classification of Hunt and Hess on admission were evaluated to determine the incidence of epilepsy 1 to 3 years (mean, 1.4 years) after aneurysmal subarachnoid hemorrhage (SAH) and surgery. Sixty-three patients had died and one patient was lost to follow-up. Twenty-nine patients developed epileptic seizures after the SAH and surgery. The mean time from the SAH to epileptic seizure varied from 0 days (day of the SAH) to 2 years (mean, 6.7 months). The seizures were classified as focal in 9 patients (31%) and as generalized in 20 patients (69%). All patients received anticonvulsant medication after more than one seizure. The risk factors for development of posthemorrhagic/postoperative epilepsy were, in order of importance: a history of hypertension; an infarct on late computed tomographic scan; and the duration of coma after the ictus. Of the 85 patients with histories of hypertension, 17 (20.0%) developed epilepsy. Only 12 (5.4%) of the 222 nonhypertensive patients developed epileptic seizures. The difference between the groups was significant (P = 0.0001). Computed tomographic scans were undertaken in 237 patients 1 to 3 years (mean, 1.4 years) after the SAH and surgery. Postoperative epilepsy was significantly associated with infarcts visualized on computed tomographic scan (P = 0.0005).