Epilepsy surgery: introduction and overview.
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Brain Diseases↗
Biomedical subjects
I A Awad
Publications and source records attributed to I A Awad.
Sclerosing vasculopathy of the central nervous system in nonelderly demented patients.
Three nonelderly patients without hypertension whose clinical and radiologic features otherwise resembled Binswanger's subcortical arteriosclerotic encephalopathy underwent biopsy of the hyperintense periventricular lesions seen on magnetic resonance imaging. The pathologic findings of the periventricular lesions consisted of gliosis with mild rarefaction and edema of the white matter. All patients had a sclerosing vasculopathy of unknown cause, which involved numerous small vessels within the periventricular lesions. The vessels stained negatively for amyloid, amyloid precursors, desmin, vimentin, keratin, immunoglobulin, and complement. On electron microscopy, small arteries, arterioles, venules, and capillaries were characterized by swollen astrocytic foot processes surrounding the vessels; dense, perivascular collagen packing; crystalline arrays of filaments within basement membrane; giant lipid-laden lysosomes within perivascular cells; and narrowing of the vascular lumina. Similar changes were not seen in a control group of 19 patients. The pathologic features of the vessels in these cases are distinct from the vasculopathy associated with Binswanger's subcortical arteriosclerotic encephalopathy. We suggest that a spectrum of vasculopathies may be associated with dementia and periventricular hyperintense lesions on magnetic resonance imaging.
Adult↗
Perioperative management and outcome after surgical treatment of anterior cerebral artery aneurysms.
The authors present clinical experience with 28 cases of ruptured anterior cerebral artery (ACA) aneurysms managed personally during a 36 month period, and 10 unruptured ACA aneurysms. The cases included five giant aneurysms and four distal ACA aneurysms. Management strategy was uniform and included early operative intervention (except in the setting of deteriorating neurologic deficit, not attributable to hydrocephalus or hematoma), and vasospasm prophylaxis including calcium channel blockers and hypervolemic hemodilution and arterial hypertension. Modern diagnostic adjuncts including transcranial doppler were used as they became available. Good outcome (outcome grade 1 or 2) was observed at 6 months in 71% (20/28) of ruptured cases and in 90% (9/10) of unruptured cases; fair outcome (outcome grade 3) was observed in 14% (4/28) of ruptured cases and in 10% of unruptured cases; bad outcome (outcome grade 4 or 5) was observed in 14% (4/28) of ruptured cases. There were no instances of rebleeding after admission to the hospital. There was a single mortality in a patient moribund on admission. Delayed ischemic deterioration (DID) was documented in 46% (13 of 28) of the ruptured cases, and was a major source of morbidity in 7 of the 9 instances of fair or poor outcome in the series. Management outcome, including the occurrence of subtle neuropsychological difficulties commonly described in cases with ACA aneurysms, is discussed with relation to the incidence of DID, the clinical course of DID, and the possible impact of various therapeutic strategies.
Adult↗
Surgical management of syringomyelia: a five year experience in the era of magnetic resonance imaging.
We summarize our experience with 59 consecutive surgically managed cases of syringomyelia (SM) over a 5 year period. All cases had magnetic resonance imaging (MRI) preoperatively and postoperatively. Twenty-eight patients presented with SM and the adult Chiari (Chiari I) malformation (SM-ACM), 6 patients had post traumatic syrinxes, 14 patients had syrinxes associated with an intramedullary neoplasm, 3 patients had syringomyelia associated with spinal arachnoiditis and 8 patients had idiopathic syringomyelia. Holocord syrinxes were more often associated with SM-ACM, while focal syrinxes were associated with posttraumatic, spinal arachnoiditis and neoplastic conditions. In all cases with neoplasms the MRI revealed parenchymal intramedullary signal abnormalities in addition to the syrinx cavity. Posterior fossa decompression with obex plugging (the Gardner operation) was the procedure of choice for SM-ACM and for idiopathic holocord syringomyelia. Exploration and drainage of the syrinx with or without shunting was carried out mainly for focal syrinxes associated with trauma and neoplasm. Patients with SM-ACM responded well to posterior fossa decompression with satisfactory results in 24/28 patients. Idiopathic SM is probably a forme fruste of SM-ACM and when treated with the Gardner procedure showed good results in all 8 patients. Posttraumatic and neoplastic SM had the least predictable results with surgery. The disappearance of the syrinx on postoperative MRI correlated well with a good surgical outcome.
Adolescent↗
A new class of electrodes of 'intermediate invasiveness': preliminary experience with epidural pegs and foramen ovale electrodes in the mapping of seizure foci.
Non-invasive electroencephalographic (EEG) recording with scalp and sphenoidal leads is often insensitive to precise localization of ictal onset, and can be distorted by skull defects and underlying lesions or deformities of the brain. We present preliminary experience with epidural pegs and foramen ovale electrodes used in 30 cases of intractable partial epilepsy where non-invasive EEG did not define a zone of epileptogenesis with sufficient precision to recommend resection, or to dictate precise placement of depth electrodes or subdural girds. Custom designed mushroom shaped peg electrodes were implanted via 4.5 mm twist-drill skull holes for epidural recording from cortical areas of suspected epileptogenesis. Foramen ovale electrodes (flexible 3-contact leads) were introduced via percutaneous puncture of Meckel's cave cistern for recording from mesiotemporal regions. Chronic recording was performed for 4 to 26 days (mean 9.2 days). There were no serious complications and signal quality was excellent in every electrode. Based on interictal and ictal records, resective surgery was performed in 8 cases, more focused further invasive recording was recommended in 15 cases (with subsequent resective surgery), and surgical options were excluded in 7 cases. It is concluded that these electrodes of 'intermediate invasiveness' represent a safe and effective tool in the armamentarium for mapping complicated or elusive epileptic foci. They can be used in lieu of, in addition to, or prior to more invasive measures. Their greatest advantage lies in their relative safety and ability to survey extensive zones of suspected epileptogenesis so as to guide and focus further mapping and surgical intervention.
Adolescent↗
Delayed facial nerve palsy after temporal lobectomy for epilepsy: report of four cases and discussion of possible mechanisms.
Four cases of idiopathic peripheral facial nerve palsy were documented after 110 consecutive resections of the temporal lobe for intractable epilepsy. In 3 of the 4 cases, the palsy was ipsilateral to the side of the temporal lobectomy. The onset of facial weakness was delayed 7 to 13 days after surgery (mean, 9.7 days). One patient underwent facial electroneurography, which documented 17% of normal facial motor function at the height of his weakness and the absence of the acoustic stapedius reflex. All patients were treated with prednisone (60-80 mg per day by mouth for 10-14 days, tapering off throughout the subsequent week). Facial function recovered fully in all patients within 6 to 8 weeks. Possible mechanisms are discussed, including heat and/or mechanical trauma to the facial nerve near the geniculate ganglion during resection of mesial temporal lobe structures.
Adult↗
Second operation after the failure of previous resection for epilepsy.
We present our surgical experience with second operations in 15 patients with recurrent intractable partial seizures after resection for epilepsy. The interval from the first operation until the first recurrence of seizures ranged from 1 day to 7 months (mean, 62 days). The interval between the first and second operations ranged from 3 months to 12 years (mean, 38 months). Detailed video-electroencephalographic interictal and ictal recording was performed in all patients (invasive electrodes were used in 11 patients). Ictal onset was shown to be remote from the zone of previous resection in 3 of 15 cases (all 3 extratemporal and in the ipsilateral hemisphere). Recurrent seizures arose from the area of previous extratemporal resection in 2 of 15 patients, and from the area of previous temporal resection in 10 of 15 patients. Both cases of extratemporal recurrences and 3 of the 10 cases of temporal lobe recurrences in the area of previous resection were associated with residual unresected structural lesion. Of the 10 patients with local temporal recurrence, 6 had proven epileptogenicity in the residual mesial structures, and 4 had residual epileptogenicity in the unresected lateral temporal lobe. The patients have been monitored for 8 to 82 months (mean, 18 months) after the second operation: 7 patients (47%) have remained seizure-free and another 5 (33%) have achieved a reduction in seizure frequency of more than 90%. There was no mortality or significant morbidity in this series. We conclude that the extent and distribution of residual epileptogenicity after failed epilepsy surgery are highly variable.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Extent of mesiobasal resection determines outcome after temporal lobectomy for intractable complex partial seizures.
The extent of resection was assessed in 94 patients who underwent temporal lobectomy for medically intractable complex partial seizures originating from a unilateral seizure focus in the anteromesial temporal lobe. Postoperative magnetic resonance imaging in the coronal plane was used to quantify the extent of resection of lateral and mesiobasal structures according to a 20-compartment model of the temporal lobe. Successful seizure outcome (greater than or equal to 90% reduction in seizure frequency) was accomplished in 83% of the patients (all followed up for more than 1 year; mean duration of follow-up, 25.2 months) and correlated significantly (P less than 0.05) with the extent of mesiobasal resection, regardless of the extent of resection of lateral structures. Successful seizure outcome was accomplished in 81% of the patients with no structural lesions, and also correlated significantly (P less than 0.05) with the extent of mesiobasal resection regardless of the extent of lateral resection. A successful seizure outcome was accomplished in 90% of the 21 patients with structural lesions documented by neuroimaging studies. Two patients who underwent extensive lobectomy without resection of the structural lesion had no reduction in seizure frequency postoperatively. We conclude that the most important factor in determining the outcome of temporal lobectomy in patients with unilateral anteromesial temporal lobe epileptogenicity is the extent of resection of structures in the mesiobasal temporal lobe. In patients with structural lesions, lesion resection may be an added contributor to successful seizure outcome.
Epilepsy, Temporal Lobe↗
Reversal of a dense, persistent, holohemispheric neurological deficit after an endarterectomy of the carotid artery: case report.
The role and timing of a carotid endarterectomy in the setting of an acute ischemic stroke-in-evolution remain controversial. Although computed tomographic (CT) scans typically show no abnormalities in the acute stage, it is generally agreed that a dense neurological deficit (hemiplegia) and/or multiple modality neurological disturbance (involving motor, sensory, gaze, and visual field impairment) represent contraindications to surgical intervention. We present a case of an acute right holohemispheric neurological deficit including dense hemiplegia, hemisensory loss, gaze disturbance, hemineglect, and impaired level of consciousness. This persisted for 4 days while serial CT scans showed no evidence of infarction. Angiography revealed pre-occlusive stenosis of the right internal carotid artery with sluggish antegrade flow. The anterior collaterals of the circle of Willis were impaired, and the right middle cerebral artery territory filled via the posterior communicating artery. Despite the dense neurological deficit persisting for 4 days, a carotid endarterectomy was performed. Gradual neurological improvement was noted within hours of the operation, and all neurological deficits resolved within the subsequent 3 days. This case is consistent with prolonged holohemispheric hemodynamic compromise below the threshold of neurological dysfunction, but above the threshold of tissue infarction ("idling neurons"). Features assisting in the recognition of this unusual scenario and the indications and risks of revascularization in this setting are discussed.
Aged↗
Prediction of cognitive change as a function of preoperative ability status among temporal lobectomy patients seen at 6-month follow-up.
The relationship between preoperative ability levels and postoperative changes in cognitive function was examined among 23 left (LTL) and 19 right (RTL) temporal lobectomy patients using a battery of memory, language, and visuospatial tasks administered approximately 3 months before surgery and at 6 months follow-up. Higher preoperative performances on the memory and language measures were associated with larger decrements in postsurgical scores among the LTL patients. The RTL group showed no consistent relationship between preoperative ability levels and subsequent postsurgical cognitive changes. Based on the present data, we constructed base-rate tables for the Wechsler Memory Scale-Revised indicating the likelihood of measurable gains or losses in memory as a function of presurgical ability level for patients undergoing LTL. While tentative, these data provide a useful and practical guide for counseling prospective epilepsy patients of the attendant cognitive risks of LTL.
Analysis of Variance↗
Natural history of the cavernous angioma.
The incidence and natural history of the cavernous angioma have remained unclear in part because of the difficulty of diagnosing and following this lesion prior to surgical excision. The introduction of magnetic resonance (MR) imaging has improved the sensitivity and specificity of diagnosing and following this vascular malformation. Seventy-six lesions with an MR appearance typical of a presumed cavernous angioma were discovered in 66 patients among 14,035 consecutive MR images performed at the Cleveland Clinic between 1984 and 1989. Follow-up studies in 86% of the cases over a mean period of 26 months provided 143 lesion-years of clinical survey of this condition. The most frequent presenting features were seizure, focal neurological deficit, and headache. While most lesions exhibited evidence of occult bleeding on MR imaging, there was overt hemorrhage in seven of the 57 symptomatic patients and only one overt hemorrhage occurred during the follow-up interval. The annualized bleeding rate was 0.7%. Analysis of the hemorrhage group revealed a significantly greater risk of overt hemorrhage in females. Pathological confirmation of cavernous angioma was obtained in all 14 surgical cases. This information assists in rational therapeutic planning and prognosis in patients with MR images showing lesions suggestive of cavernous angioma.
Adolescent↗
Symptomatic Chiari malformation in adults: a new classification based on magnetic resonance imaging with clinical and prognostic significance.
Thirty-five consecutive adults with Chiari malformation and progressive symptoms underwent surgical treatment at a single institution over a 3-year period. All patients underwent magnetic resonance imaging scan before and after surgery. Images of the craniovertebral junction confirmed tonsillar herniation in all cases and allowed the definition of two anatomically distinct categories of the Chiari malformation in this age group. Twenty of the 35 patients had concomitant syringomyelia and were classified as Type A. The remaining 15 patients had evidence of frank herniation of the brain stem below the foramen magnum without evidence of syringomyelia and were labeled Type B. Type A patients had a predominant central cord symptomatology; Type B patients exhibited signs and symptoms of brain stem or cerebellar compression. The principal surgical procedure consisted of decompression of the foramen magnum, opening of the fourth ventricular outlet, and plugging of the obex. Significant improvement in preoperative symptoms and signs was observed in 9 of the 20 patients (45%) with syringomyelia (Type A), as compared to 13 of the 15 patients (87%) without syringomyelia (Type B). Postoperative reduction in syrinx volume was observed in 11 of the 20 patients with syringomyelia, including all 9 patients with excellent results. Magnetic resonance imaging has allowed a classification of the adult Chiari malformation in adults based on objective anatomic criteria, with clinical and prognostic relevance. The presence of syringomyelia implies a less favorable response to surgical intervention.
Adult↗
Intracranial hypertension associated with unruptured cerebral arteriovenous malformations.
Only 6 patients with intracranial hypertension associated with unruptured cerebral arteriovenous malformations have been reported. We report 6 additional patients seen at the Cleveland Clinic during the past 10 years. The average age was 28 years (range, 19-44 years); 4 were women. Symptoms and signs included papilledema (6 patients), headache (6), transient nonepileptic focal symptoms (4), visual obscurations (3), ipsilateral carotid or ocular bruits (3), abnormal visual fields (3), focal seizures (2), and progressive visual loss (1). Enhanced computed tomography (CT) or magnetic resonance imaging (MRI) demonstrated the malformations in all 6 patients. The malformations were large, supplied by the branches of the middle and anterior cerebral arteries, with the posterior cerebral artery contributing in 3 patients, and all drained into the superior sagittal sinus. Associated venous obstruction was seen in 2 patients. Four patients underwent excision of the arteriovenous malformation, with resolution of papilledema in all 4. Measurements of cortical arterial and venous pressures during surgery in 3 patients showed decreased feeding artery pressures and elevated draining vein pressures, which normalized after removal of the malformation. Treatment in the 2 remaining patients consisted of medical therapy (acetazolamide, furosemide, steroids) alone in 1 patient, and in conjunction with proton beam radiation in the other. Papilledema resolved in the former patient, but the patient receiving proton beam radiation still had papilledema 2 years later. Intracranial hypertension associated with unruptured cerebral arteriovenous malformations occurs in young patients with high flow malformations that drain into the superior sagittal sinus, and is likely the result of increased cortical venous and superior sagittal sinus pressure. Excision of the malformation effectively reduces the intracranial pressure.
Adult↗
Intractable complex partial seizures associated with occult temporal lobe encephalocele and meningoangiomatosis: a case report.
Occult congenital temporal lobe encephalocele has rarely been reported in association with medically intractable complex partial seizures. The four previously reported cases were unsuspected preoperatively. We present the case of an 18-year-old woman with intractable complex partial seizures since age 13. Seizure onset was electrically localized to the right temporal lobe. Preoperative neuroimaging studies revealed a middle fossa defect and inferior herniation of the right temporal lobe. Pathologic examination of the resected encephalocele revealed prominent features of meningoangiomatosis. We believe this to be the first case of temporal lobe encephalocele and epilepsy to be diagnosed preoperatively, and the first case also to be associated with meningoangiomatosis. The relevant literature on meningoangiomatosis and on temporal lobe encephalocele as a cause of epilepsy is reviewed.
Adolescent↗
Intraoperative determination of the extent of corpus callosotomy for epilepsy: two simple techniques.
There is increasing interest in staged corpus callosotomy for intractable generalized epilepsy. At the first procedure, a portion (usually the anterior two-thirds) of the corpus callosum is sectioned. If seizures persist, completion of callosotomy or alternative treatment approaches can be considered. It is obviously important to ascertain that the desired extent of callosotomy was in fact accomplished at the time of initial operation. Our experience and the published literature indicate that the surgeon's impression at operation can be erroneous. We describe a technique of determining extent of corpus callosotomy during the procedure. The magnetic resonance imaging (MRI) scan in the midsagittal plane is used to select the desired extent of callosotomy. That point on the corpus callosum is characterized using simple planar geometry in relation to three anatomic landmarks in that same plane: the glabella, the inion, and the bregma (midline intersection of the coronal suture). The same point along the corpus callosum can then be located on a lateral skull x-ray using these same three anatomic landmarks. At surgery, an intraoperative lateral skull x-ray is obtained with a marking clip, thereby verifying the actual extent of callosotomy. We have verified the reliability of this scheme in 5 callosotomy procedures and have used this technique for intraoperative localization of midline and parasagittal targets in another 7 cases (3 tumors, 2 aneurysms, and 2 placements of interhemispheric subdural grids). In addition, we reviewed corpus callosum topography on 25 randomly selected MRI scans.(ABSTRACT TRUNCATED AT 250 WORDS)
Corpus Callosum↗
Epidural peg electrodes for the presurgical evaluation of intractable epilepsy.
A new electrode design for the extradural recording of electrical brain activity is described. Epidural peg electrodes are implantable mushroom-shaped composites of Silastic elastomer and a stainless steel or platinum disc. These electrodes are useful for the preoperative mapping of seizure foci in some patients who have cranial defects or severe muscle artifacts on scalp recordings. They are also used for canvassing wide areas of cortex to determine whether a seizure is focal in origin, arises diffusely from a hemisphere, or has a bilateral origin. Advantages of epidural peg electrodes over screw and other types of epidural electrodes include low risk of infection or hemorrhage and improved patient comfort.
Electrodes, Implanted↗
Ipsilateral leg weakness associated with carotid stenosis.
Ipsilateral motor or sensory symptoms associated with carotid occlusive diseases are rare. We report a 52-year-old man who presented with aphasia, right hemiparesis, mild left leg weakness, and bilateral Babinski's signs. During the previous 10 days, he had experienced three episodes of left leg numbness and incoordination that occurred either alone or in association with right arm and leg weakness. Computed tomography showed infarcts in the right frontoparietal (parasagittal), left frontal, and left parietal lobes. Cerebral angiography revealed 60% stenosis of the right internal carotid artery, 80% stenosis of the left internal carotid artery, absence of the A1 segment of the right anterior cerebral artery, filling of the right anterior cerebral artery from the left carotid circulation only, and a normal vertebrobasilar system. This report illustrates that leg weakness may occur ipsilateral to carotid disease if the contralateral anterior cerebral artery is supplied by the ipsilateral carotid artery.
Carotid Arteries↗
Neurological deterioration in a patient with a spinal arteriovenous malformation following lumbar puncture. Case report.
The mechanism of nonhemorrhagic neurological deterioration from spinal arteriovenous malformation (AVM) and the role of acute surgical intervention in this setting are not well understood. The case is described of a 65-year-old man who presented with a 2-year history of mild gait spasticity and vague sensory complaints affecting both lower extremities. Following a diagnostic lumbar puncture, these symptoms progressed painlessly over a 4-day period to total motor paraplegia, urinary retention, and hypesthesia in all modalities with a midthoracic sensory level. Magnetic resonance imaging showed a probable spinal AVM but no evidence of hemorrhage or cord compression. Spinal angiography confirmed the diagnosis of spinal AVM fed by radicular branches of left T-7 and T-8 segmental intercostal arteries. Drainage was via long dorsal veins caudally. Emergency laminectomy with intradural exploration was performed. There was no evidence of prior hemorrhage or focal mass effect, although the cerebrospinal fluid pressure was elevated. The dural component of the spinal AVM was excised, and its communications with the spinal cord were disconnected intradurally. Neurological function started improving within 6 hours of the patient awakening from anesthesia. He had achieved antigravity strength in every muscle group of the lower extremities by the time of discharge to a rehabilitation center 10 days after surgery. Three months postoperatively, he was ambulating with a walker and was continent of urine and stool. Possible pathophysiological mechanisms are discussed in light of the favorable response to timely surgical intervention.
Aged↗