Surgical Outcomes in Post-Traumatic Epilepsy: A Single Institutional Experience.

BACKGROUND: Post-traumatic epilepsy (PTE) is a debilitating sequela of traumatic brain injury (TBI), occurring in up to 20% of severe cases. This entity is generally thought to be more difficult to treat with surgical intervention. OBJECTIVE: To detail our experience with the surgical treatment of PTE. METHODS: Patients with a history of head injury undergoing surgical treatment for epilepsy were retrospectively enrolled. Engel classification at the last follow-up was used to assess outcome of patients that underwent surgical resection of an epileptic focus. Reduction in seizure frequency was assessed for patients who underwent vagal nerve stimulator (VNS) or responsive neurostimulator (RNS) implantation. RESULTS: A total of 23 patients met inclusion criteria. Nineteen (82.6%) had mesial temporal sclerosis, 3 had lesional neocortical epilepsy (13.0%), and 1 had nonlesional neocortical epilepsy (4.3%). Fourteen patients (60.9%) underwent temporal lobectomy (TL), 2 underwent resection of a cortical focus (8.7%), and 7 underwent VNS implantation (30.4%). Three patients underwent RNS implantation after VNS failed to reduce seizure frequency more than 50%. In the patients treated with resection, 11 (68.8%) were Engel I, 3 (18.8%) were Engel II, and 2 (12.5%) were Engel III at follow-up. Average seizure frequency reduction in the VNS group was 30.6% ± 25.6%. RNS patients had reduction of seizure severity but seizure frequency was only reduced 9.6% ± 13.6%. CONCLUSION: Surgical outcomes of PTE patients treated with TL were similar to reported surgical outcomes of patients with nontraumatic epilepsy treated with TL. Patients who were not candidates for resection demonstrated variable response rates to VNS or RNS implantation.

Epileptogenic focus localization in treatment-resistant post-traumatic epilepsy.

Pharmacologically intractable post-traumatic epilepsy (PTE) is a major clinical challenge for patients with penetrating traumatic brain injury, where the risk for this condition remains very high even decades after injury. Although over 20 anti-epileptic drugs (AED) are in common use today, approximately one-third of epilepsy patients have drug-refractory seizures and even more have AED-related adverse effects which compromise life quality. Simultaneously, there have been repeated recommendations by radiologists and neuroimaging experts to incorporate localization based on electroencephalography (EEG) into the process of clinical decision making regarding PTE patients. Nevertheless, thus far, little progress has been accomplished towards the use of EEG as a reliable tool for locating epileptogenic foci prior to surgical resection. In this review, we discuss the epidemiology of pharmacologically resistant PTE, address the need for effective anti-epileptogenic treatments, and highlight recent progress in the development of noninvasive methods for the accurate localization of PTE foci for the purpose of neurosurgical intervention. These trends indicate the current emergence of promising methodologies for the noninvasive study of post-traumatic epileptogenesis and for the improved neurosurgical planning of epileptic foci resection.

[Pharmacoresistant epilepsy after craniocerebral injury]. / Farmakorezistentní epilepsie po kraniocerebrálním poranení.

INTRODUCTION: Posttraumatic epilepsy is one of the possible serious consequencies of both closed and open head injury with clinical manifestation months or years after surgery. In pharmacoresistant patients, surgical therapy should be considered. MATERIAL AND METHODS: The study summarises the results of surgical treatment of pharmacoresistant posttraumatic epilepsy in a group of 13 patients (11 males and 2 females). Average age at the time of injury was 9.6 years in males and 8.8 years in females. The average number of seizures was 10.7-17 seizures/month preoperatively. Invasive EEG monitoring was required in 5 patients in whom non invasive or semiinvasive investigations failed to localize the epileptogenic zone adequately. Temporal lobe resections were performed in 4 patients, 4 patients underwent extratemporal resections and vagus nerve stimulation system was implanted in 5 patients. RESULTS: Three patients (75%) after temporal resections became seizure free (Engel I) and in the remaining patient significant reduction of seizures was achieved (Engel III). There were 2 seizure free patients after extratemporal resections (50%) and significant reduction of seizure rates was achieved (Engel III) in the remaining two. One patient after vagus nerve stimulation met the criteria for > 90% response and there was a 50-90% seizure rate reduction in the remaining 4 patients (vagus nerve stimulation responder). CONCLUSIONS: Although in limited group of patients the study confirms good results of surgical treatment of selected posttraumatic epilepsy patients--mainly temporal epilepsy patients and patients after vagus nerve stimulation. Meticulous presurgical evaluation including invasive encephalography in indicated patients is a precondition for surgical success.

Aphasic or amnesic status epilepticus detected on PET but not EEG.

PURPOSE: To describe five patients with ictal aphasia and one patient with ictal amnesia, who had focal positron emission tomography (PET) hypermetabolism but no clear ictal activity on electroencephalography (EEG). METHODS: (18)F-Fluorodeoxyglucose (FDG)-PET scans with concomitant EEG were obtained in five patients with suspected ictal aphasia or ictal amnesia without ictal activity on EEG. We reviewed medical history, EEG, imaging data, and treatment outcome. RESULTS: Brain magnetic resonance imaging (MRI) showed no structural abnormalities in any of the patients. EEG showed left temporal irregular delta activity in three patients, with aphasia and nonspecific abnormalities in two other patients, all without clear ictal pattern. All patients demonstrated focal hypermetabolism on PET scan. The hypermetabolism was in the left frontotemporal region in patients with ictal aphasia and in the bilateral hippocampal region in the patient with amnesia. Three patients who received intravenous benzodiazepines during their episodes had transient clinical improvement. With antiepileptic drug (AED) treatment, symptoms gradually resolved in all patients. Concomitant resolution of PET hypermetabolism was documented in three patients who had follow up scans. One patient with ictal aphasia later developed recurrent episodes, each with recurrent PET hypermetabolism. This patient and one other patient required immune-modulating therapy in addition to AEDs. DISCUSSION: FDG-PET imaging should be considered as a diagnostic tool in patients with suspected ictal aphasia or amnesia, who fail to show clear evidence of ictal activity on EEG.

Characteristics and surgical outcomes for medial temporal post-traumatic epilepsy.

A common post-traumatic location of epileptogenesis is the medial temporal lobe despite evidence of associated diffuse or remote cerebral injury. We undertook a review of post-traumatic medial temporal lobe epilepsy (MTLE) patients as part of an overall post-traumatic epilepsy population to assess the extent of cerebral injury sustained by this subpopulation and to establish whether surgical outcome differed from that of a non-traumatically-induced epilepsy population. A retrospective review of 57 patients operated for post-traumatic epilepsy (PTE) over a 10-year period (1993-2003) was undertaken with particular attention to those undergoing medial temporal resection. Preoperative magnetic resonance imaging (MRI) was assessed for the type and location of abnormalities. Postoperative outcomes were compared with those of patients with MTLE of non-traumatic origin operated by the same surgeon. Of the 57 patients operated, 30 cases underwent medial temporal lobe resection. The most common mechanism of injury was blunt trauma attributable to motor vehicle accidents with imaging abnormalities characterized by medial temporal sclerosis (MTS; 16 cases), T2/FLAIR hyperintensities (nine cases), periventricular gliosis (seven cases), diffuse cerebral atrophy (five cases) and focal encephalomalacia (three cases). Six patients had normal MRI studies. No significant differences in postoperative outcomes were found between post- and non-traumatic MTLE epilepsy groups. The presence of histopathological change in the medial temporal lobe varied greatly and provided no indication of a favourable postoperative outcome. Patients with post-traumatic medial temporal lobe epilepsy respond favourably to surgical treatment. In the case of medial temporal sclerosis, there is substantial variation of histopathological findings which correlate poorly with current imaging applications. The favourable outcomes obtained following surgery in this group attest to a commonality with other risk factors in the genesis of epilepsy in this location.

Effectiveness of cerebral hemispherotomy for improving behavioral disorders associated with intractable post-traumatic seizures.

A 25-year-old man presented with intractable post-traumatic seizures after suffering cerebral contusion in a traffic accident at age 5 years. Cerebral hemispherotomy was performed to transect the neuronal fibers to interrupt connections between seizure foci in wide areas of the brain, and to minimize the resected brain parenchyma. His seizures resolved and behavioral disorders improved, which had been impaired since age 8 years. Increased glucose metabolism in the normal frontal lobe detected by interictal fluorodeoxyglucose-positron emission tomography was correlated with the improvements in behavioral disorders. These findings suggest that the effects of seizures may be reversible in brain areas connected with, but remote from, the epileptogenic cortex.

[Clinical features and surgical treatment of posttraumatic epilepsy].

OBJECTIVE: To study the clinical features of posttraumatic epilepsy and evaluate the surgical procedures for anti-epileptic treatment and their therapeutic effects. METHODS: Neurological and scalp EEGs were performed in 35 patients with posttraumatic epilepsy, who also underwent CT, MRI examination, single photon emission computerized tomography (SPECT) and positron emission tomography (PET) prior to intracranial surgery, with intraoperative monitoring of the cortical EEG. RESULTS: With the cortical EEG monitoring, 16 patients underwent surgical resection of the epileptogenic foci identified by intraoperative EEG, 7 had multiple subpial transection and 12 received stereotactic radiosurgery for the epileptogenic foci localized by PET. In most of the cases, the epileptogenic foci were located around the lesions of encephalomalacia. During the follow-up of 32 patients varying from 1 to 4 years, 18 patients became seizure free, 10 had obvious reduction in the frequency of seizure while 4 failed to respond favorably to the treatment. CONCLUSIONS: Seizures of posttraumatic epilepsy may aggravate the brain dysfunction due to primary trauma, and surgical treatment often yields good effect and lessens the toxic and adverse effect of antiepileptic drugs. Stereotactic radiosurgery guided by PET is safe and effective in the treatment of patients with posttraumatic epilepsy.

Surgical treatment of late-onset post-traumatic partial seizures in a child.

INTRODUCTION: Although post-traumatic epilepsy accounts for a small number of epileptic patients, it should not be underestimated since it primarily affects children and young adults and can result in psychosocial disability and death. CASE REPORT: We present the case of a 14-year-old girl referred to us because of refractory partial seizures. The patient had experienced a head trauma at the age of 6 months requiring surgical treatment due to a large right fronto-temporo-parietal extradural hematoma. She was discharged on phenytoin prophylactically. At the age of 4 she had her first partial seizure, characterized by left arm and leg tonic-clonic movements. Her physical examination revealed a subtle left brachiocrural hemiparesis and developmental delay. Several antiepileptic drugs were tried and seizure control was not achieved. They were occurring 8-10 times per day. The proposed surgical treatment was based on the consistent seizure semiology and on the affected area as identified by MRI and visible macroscopically to the neurosurgeon. At 9 years follow-up the patient is seizure free. Her motor skills are adequate for living a normal life. CONCLUSION: We emphasize that selected patients may benefit from surgical treatment when epilepsy results from a trauma.

The structural basis of moderate disability after traumatic brain damage.

The objective was to discover the nature of brain damage in survivors of head injury who are left with moderate disability. Macroscopic and microscopic examination was carried out on the brains of 20 persons who had died long after a head injury that had been treated in a neurosurgical unit. All had become independent but had various disabilities (moderate disability on the Glasgow outcome scale) Most deaths had been sudden, which had led to their referral from forensic pathologists. Post-traumatic epilepsy was a feature in 75%. An intracranial haematoma had been evacuated in 75%, and in 11 of the 15 with epilepsy. Diffuse axonal injury was found in six patients, five of the mildest type (grade 1) and one of grade 2. No patient had diffuse thalamic damage but one had a small focal ischaemic lesion in the thalamus. No patient had severe ischaemic brain damage, but three had moderate lesions which were bilateral in only one. No patient had severe cortical contusions. In conclusion, the dominant lesion was focal damage from an evacuated intracranial haematoma. Severe diffuse damage was not found, with diffuse axonal injury only mild and thalamic damage in only one patient.

Rightward attentional bias and left hemisphere dominance in a cue-target light detection task in a callosotomy patient.

Six normal subjects and a callosotomized man with a prefrontal lesion, mostly on the right side, were tested in a reaction time (RT) task involving a key-pressing response to an extrafoveal light target preceded by an extrafoveal light cue. Cues and targets were presented along the horizontal meridian at 4 degrees and 12 degrees on the right and left of fixation. Fixation was maintained throughout each trial. The cue signalled the occurrence of the target within a time window extending from 200 to 4000 misec from the cue, but did not predict target location. Normal controls responded faster to medial than to lateral targets in both fields, but showed no between-field difference, and their RT was not affected by cue location. Furthermore, they showed the so-called 'ipsilateral inhibition' or 'inhibition of return' effect, their RT being longer when cues and targets occurred in the same field than when they occurred in opposite fields. The RT of the callosotomized subject showed a left-right gradient for both cue location and target location, being longest for the leftmost location and shortest for the right locations. In addition, he showed a significant advantage for the right hand regardless of cue and target location, as well as a consistent ipsilateral inhibition in the left field, whereas in the right field there was ipsilateral inhibition only at the two longest stimulus onset asynchronies. These results suggest that, at least under these experimental conditions, there was a rightward orientational bias which reflected the taking over of the control of performance by the left hemisphere. This attentional bias was reminiscent of that seen in patients with hemi-inattention from right hemisphere damage, although the callosotomized patient showed no sign of such hemi-inattention in routine clinical tests. On the basis of several considerations the rightward bias could be attributed to the callosal interhemispheric disconnection rather than to the right prefrontal lesion.

Benjamin Winslow Dudley and early American trephination for posttraumatic epilepsy.

Benjamin Winslow Dudley (1785-1870) was a Kentucky frontier surgeon who received basic medical education in the United States and extensive surgical training in Europe. He returned to Lexington to become a dominant figure and the most prominent surgical teacher in the Mississippi Valley. Written evidence of Dudley's operative accomplishments are sparse, but he seems to have combined the finest French (Dominique Jean Larrey, Guillaume Dupuytren) and British (Henry Cline, John Abernethy, Astley Cooper) surgical training with conservative and thoughtful patient selection. His operative endeavors in the preantiseptic era included trephination for posttraumatic epilepsy in six patients (1819-1832). This was the largest recorded series of such cases, and it stimulated other American surgeons to trephine for relief of posttraumatic seizures. Trephination for decompression and debridement was undertaken at the site of original injury to remove the cause of "cerebral excitement" and restore "corporeal and intellectual function." Dudley considered this a safe operation in "cautious, firm, and intelligent hands." He thought crowded urban hospitals were unsafe and attributed his better surgical results to the clean, rural Kentucky air. Dudley's achievement is contrasted with other Early American preantiseptic trephinations for posttraumatic epilepsy.

Multiple subpial transection for treatment of intractable epilepsy.

On the basis of experimental study, we applied multiple subpial transection (MST) to treat 50 patients with intractable epilepsy in which epileptigenic lesion involved functional areas such as pericentral gyrus, postcentral gyrus, Broca's area, Wernicke's area, visual cortex, etc. They were followed up for 6 to 40 months. Complete control of seizures was obtained in 32 patients, significant reduction of seizure (more than 50%) in 13, reduction (less than 50%) in 3, and no effect in 2. The total effective rate was 96%. No functional defect was found in all patients. The mechanism of the disease and surgical technique were discussed in detail. We consider that MST could replace some standard excisional therapy for local epilepsy.

Relative risk of deterioration after mild closed head injury.

In this prospective study, a series of 1812 consecutive mild head injured adult patients who visited the hospital emergency department were assessed. Twenty-eight patients (1.5%) deteriorated after head injury; 23 of these (1.3% of the series) required surgical intervention. Five patients (0.3%) deteriorated due to non-surgical causes [post-traumatic seizure 2, syndrome of inappropriate secretion of antidiuretic hormone (SIADH) 3]. Most of the deterioration occurred within the first 24 hours (57%). Post-traumatic headache was found in 280 patients (15.5%) and 84 patients (4.6%) suffered post-traumatic vomiting. The relative risk is calculated. Age over 60, presence of drowsiness, focal motor weakness, post-traumatic headache and vomiting has increased risk of deterioration (p < 0.001). This study suggests that post-traumatic headache and vomiting deserve more clinical attention rather than being considered as post-traumatic syndrome only.

Amygdalo-hippocampectomy for pathological aggression.

Two patients are reported, one with severe brain damage and epilepsy, and the other with limbic epilepsy, who were treated with unilateral microsurgical amygdalo-hippocampectomy for the control of rage and aggression. Both had significant improvement in their aggressiveness, and the second patient also improved in the frequency of his seizures and psychotic episodes. The significance of these observations for our understanding of the morphophysiological basis of rage and aggression is discussed.

High-frequency EEG activity at the start of seizures.

Frequencies above 35-40 Hz are poorly visualized on conventional EEG scalp recordings. We investigated frequency components up to 150 Hz in digitally recorded EEGs of seizures in five patients with implanted subdural grids, as part of their evaluation for epilepsy surgery. Amplifier bandpass was set from 0.1 to 300 Hz, and EEG was digitized at 2,000 samples per second. Seizures with electrodecremental patterns at the start showed a significant increase in spectral power above 35 Hz, with a twofold increase in the 40-50-Hz range, and up to a fivefold increase in the 80-120-Hz portion of the spectrum. Activity above 40 Hz could represent summed action potentials, harmonics of synaptic potentials or transient sharp components of synaptic potentials. High-frequency increases were largely localized to the region of the seizure focus. Grid sites remote from the focus did not show significant energy in the EEG band above 40 Hz at baseline, nor at time of seizure onset. Our findings suggest that high-frequency recordings may be of use in localizing seizure foci.

[Surgical treatment of traumatic epilepsy].

Fifteen patients with traumatic epilepsy were treated surgically. Cortico-electroencephalography was used during the operation. Meningo-encephalo cicatrix was found in 8 patients, scar formation in brain parenchyma in 4, meningoencephalocele in 2, and porencephalia in 1. Seven of the 15 patients were examined by CT, showing more accurate localization of pathological changes. Seizure subsided in 8 patients. Anti-epileptic drugs were still used in 4 patients, but the frequency and severity of epileptic attack were obviously decreased. There was no operative mortality. The indications, techniques of the operation and the postoperative management were discussed.

Hemispheric processing of spatial frequencies in two commissurotomy patients.

To test the hypothesis that in humans the left brain hemisphere is specialized for processing high spatial frequencies while the right hemisphere is specialized for processing low spatial frequencies, pairs of Gaussian windowed sinusoidal gratings were presented for 167 msec within the left and right visual fields of two commissurotomy patients. The gratings employed had spatial frequencies ranging from 1 to 8 cycles per degree, and horizontal or vertical orientations. The two gratings in each pair were identical in spatial frequency but could differ in orientation. Subjects reported if their orientations were the same or different. Twelve normal controls were also run. Accuracy data provides no indication of a relative advantage for high frequencies in the RVF or low frequencies in the LVF. One commissurotomy subject showed a trend in the reverse direction; the other was better with LVF presentations for all spatial frequencies. Control subjects failed to show a spatial frequency x visual field interaction. These outcomes suggest that at the processing stages required by the task, the hemispheres are not specialized for particular ranges of spatial frequencies.