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PubMed2005

In vivo optical spectroscopy detects radiation damage in brain tissue.

OBJECTIVE: Magnetic resonance imaging abnormalities in malignant brain tumors after irradiation may represent either recurrent tumor or radiation injury. Optical spectroscopy may represent a novel technique to identify radiation damage in brain tissues and to differentiate contrast-enhancing lesions from recurrent tumor. METHODS: Fluorescence and diffuse reflectance spectra were acquired from 90 patients: 15 undergoing surgical resection for presumed recurrent tumor after radiation therapy, 15 with epilepsy and hippocampal sclerosis, and 60 with tumors who had not received irradiation. Optical spectra were acquired from 6 to 10 sites and were compared with a biopsy obtained from beneath the optical spectroscopy probe; the data then were classified by a neuropathologist blinded to the spectroscopy data. A probe for the intraoperative collection of diffuse reflectance and fluorescence spectra was used. RESULTS: Thirteen of 15 patients (29 of 129 spectra) with previous irradiation showed a unique spectral feature characterized by a fluorescence peak centered at 500 nm (F500). All biopsy specimens showing histopathological signs of radiation injury had the F500 on their corresponding spectra (18 of 18). The F500 was identified in another 10% (11 of 111 spectra) of samples with previous irradiation but no histologically identifiable signs of radiation damage. The F500 was never seen in the normal temporal lobe of epilepsy patients with hippocampal sclerosis (0 of 105) and was seen in only 1.5% of tumor patients who did not undergo previous irradiation (6 of 433). CONCLUSION: Optical spectroscopy detects radiation damage in brain tissues. The F500 spectral peak may allow accurate selection of tissues for biopsy in evaluating patients with new, contrast-enhancing lesions in the setting of previous irradiation.

Adult↗

PubMed1996

Minimalism through intraoperative functional mapping.

Intraoperative stimulation mapping may be used to avoid unnecessary risk to functional regions subserving language and sensori-motor pathways. Based on the data presented here, language localization is variable in the entire population, with only certainty existing for the inferior frontal region responsible for motor speech. Anatomical landmarks such as the anterior temporal tip for temporal lobe language sites and the posterior aspect of the lateral sphenoid wing for the frontal lobe language zones are unreliable in avoiding postoperative aphasias. Thus, individual mapping to identify essential language sites has the greatest likelihood of avoiding permanent deficits in naming, reading, and motor speech. In a similar approach, motor and sensory pathways from the cortex and underlying white matter may be reliably stimulated and mapped in both awake and asleep patients. Although these techniques require an additional operative time and equipment nominally priced, the result is often gratifying, as postoperative morbidity has been greatly reduced in the process of incorporating these surgical strategies. The patients quality of life is improved in terms of seizure control, with or without antiepileptic drugs. This avoids having to perform a second costly operative procedure, which is routinely done when extraoperative stimulation and recording is done via subdural grids. In addition, an aggressive tumor resection at the initial operation lengthens the time to tumor recurrence and often obviates the need for a subsequent reoperation. Thus, intraoperative functional mapping may be best alluded to as a surgical technique that results in "minimalism in the long term".

Brain↗

PubMed2001

Unsuspected atypical hemispheric dominance for language as determined by fMRI.

PURPOSE: We sought to illustrate the value of functional magnetic resonance imaging (fMRI) in the presurgical assessment of hemispheric dominance for language by means of an illustrative case report. METHODS: fMRI with two language paradigms was performed in a right-handed patient without familial sinistrality suffering from a left frontal focal epilepsy. RESULTS: Both fMRI paradigms revealed unequivocally lateralized right hemispheric activation. Atypical language representation was confirmed by Wada test. The further presurgical workup could be restricted to subdural strip recordings instead of the initially intended grid implantation. After resective surgery, no language deficits were apparent. CONCLUSIONS: Hemispheric dominance for language should be assessed by fMRI in all patients before surgery in areas potentially relevant for language in either cerebral hemisphere. fMRI may influence the further diagnostic workup and should be performed before other invasive diagnostic procedures.

Adult↗

PubMed1995

Surgical pathology of epilepsy resections in childhood.

In this review, we discuss the important pathological lesions observed in temporal lobectomies and neocortical resections performed for medically refractory seizures in children. A higher percentage of pediatric cases appear to be "lesional" with computed tomography (CT) and magnetic resonance imaging (MRI) and abnormalities and "dual pathology" lesions appear to be more common than pure mesial temporal sclerosis. Almost a third of cases appear to be neuronal migration disorders and low-grade gliomas with some lesions harboring both neoplastic and malformative components. Our experience suggests a role for cytomegalovirus in some cases of Rasmussen's encephalitis.

Brain Injuries↗

PubMed1998

Intraoperative microdialysis and tissue-pO2 measurement in human glioma.

The amino acid glutamate is one of the major neurotoxins in the pathogenesis of neuronal death after ischemia or trauma. Microdialysis studies in both man and animal have shown elevated extracellular levels after primary lesions. Monitoring of cerebral tissue oxygenation (p(ti)O2) has been used in recent years to detect and prevent episodes of low cerebral oxygenation, e.g. after trauma or subarachnoid hemorrhage. Intraoperative monitoring of p(ti)O2 combined with microdialysis in the peritumoral edema has been chosen to study the responses of glutamate and oxygen levels during resection. In 7/9 patients p(ti)O2 was below "critical" 10 mm Hg. Elevating inspiratory oxygen concentration to 100% led to an increase of p(ti)O2 by 2.5-4 fold and a decrease of glutamate and aspartate by 50-80%. A close correlation between p(ti)O2 and microdialysis glutamate levels was not clearly shown due to frequent intraoperative manipulations.

Aspartic Acid↗

PubMed2002

The usefulness of repeated ictal SPET for the localization of epileptogenic zones in intractable epilepsy.

This study investigated whether repeated ictal single-photon emission tomography (SPET) is helpful in the localization of epileptogenic zones and whether it can provide information confirming that an area of increased perfusion is really the culprit epileptogenic lesion. Fifty-four repeated ictal SPET studies were performed in 24 patients with ambiguous or unexpected findings on the first ictal SPET study. These patients were enrolled from among 502 patients with intractable epilepsy in whom pre-operative localization of epileptogenic zones was attempted with a view to possible surgical resection. Video monitoring of ictal behaviour and EEGs was performed in all patients. Repeated ictal SPET was performed using technetium-99m hexamethylpropylene amine oxime (HMPAO) when there was no prominently hyperperfused area or when unexpected findings were obtained during the first study. Two ictal SPET studies were performed in 19 patients, three studies in four patients and four studies in one patient. The average delay between ictal onset and injection was 28 s for the first study and 22 s for the second, third and fourth studies. Using interictal SPET, ictal-interictal subtraction images were acquired and co-registered with the population magnetic resonance imaging (MRI) template. Invasive study and surgery were performed in 18 patients, and in these cases the surgical outcome was known. In the other six patients, epileptogenic foci were determined using MRI, positron emission tomography (PET) and ictal EEG findings. Two patients were found to have mesial temporal lobe epilepsy, two lateral temporal lobe epilepsy, eight frontal lobe epilepsy, three parietal lobe epilepsy and one occipital lobe epilepsy. The other eight had multifocal epilepsy. The first study was normal in 12 patients (group I) and indicated certain zones to be epileptogenic in the other 12 (group II). Among group I, the correct epileptogenic zone or lateralization was revealed at the repeated study in nine patients, while in the other three it was not. Among group II, six patients showed the same results at the second study, thus confirming that the initially identified zones were of epileptogenic significance. In the other six patients, different areas were identified on the first and second studies, and repeated ictal SPET corroborated multifocality of the ictal EEG findings in five. These results indicate that repeated ictal SPET is useful because it can yield new or additional information about the epileptogenic zones and can confirm that a region of interest is an epileptogenic zone or that the epilepsy is of multifocal origin.

Adolescent↗

PubMed2006

Meningioangiomatosis associated with neurofibromatosis: report of 2 cases in a single family and review of the literature.

BACKGROUND: Meningioangiomatosis (MA) is a rare benign disorder. It may occur sporadically or in association with neurofibromatosis (NF). The sporadic type typically presents with seizures, whereas that associated with NF is often asymptomatic. Of the 100 cases reported, only 14 are associated with NF. We now report 2 additional cases of MA associated with neurofibromatosis 2 (NF2) in a single family, with one occurring in the cerebellum. The etiology, pathology, and imaging features of MA are presented. CASE DESCRIPTION: A 38-year-old woman (patient 1) presented with a 4-month history of ataxia. She had been diagnosed previously with NF2. Magnetic resonance imaging (MRI) scans of the brain revealed bilateral acoustic neuromas and multiple calcified intracranial lesions. Her 13-year-old daughter (patient 2) presented with complex partial seizures. MRI scans of the brain revealed bilateral acoustic neuromas and a right parietal mass. Patient 1 underwent a suboccipital craniotomy to resect the right-sided acoustic neuroma. A small portion of normal-appearing cerebellar cortex was resected to avoid undue retraction. Histopathologic examination showed the presence of a lesion consistent with MA. Patient 2 underwent a right temporal-parietal craniotomy to remove the enhancing epileptogenic right posterior temporoparietal lesion. Histopathologic analysis showed a lesion consistent with meningioma and MA. CONCLUSIONS: MA has been reported infrequently in association with NF2. We now report 2 cases of MA associated with NF2 in one family, and we add the cerebellum to possible locations of occurrence. MA should be considered in the differential diagnosis of cortical lesions, particularly in patients with NF2.

Adolescent↗

PubMed2001

The effects of remifentanil on epileptiform discharges during intraoperative electrocorticography in patients undergoing epilepsy surgery.

PURPOSE: High-dose i.v. opioids (e.g., alfentanil, 50 microg/kg bolus) are known to increase the intraoperative reading of epileptiform activity during epilepsy surgery (ES), thereby facilitating localization of the epileptogenic zone (i.e., the site of ictal onset and initial seizure propagation). However, this phenomenon has not been studied with remifentanil (i.e., a novel ultra-short acting opioid). The purpose of the present study was to evaluate the effect of remifentanil on electrocorticography (ECoG) during ES. METHODS: After Institutional Review Board approval, 25 adult patients undergoing elective ECoG-guided anterior temporal corticectomy were enrolled. At the time of ECoG, anesthesia consisted of inhaled isoflurane < or =0.1% (end-tidal) in 50% N2O, and i.v. fentanyl, 2 microg/kg/h and vecuronium. Patients were maintained at normocapnia and normoxia during ECoG. After acquisition of baseline ECoG, bolus remifentanil, 2.5 microg/kg i.v., was administered. The number of epileptiform spikes occurring 5 min before and after this bolus were compared by using a one-sided sign test; p values < or =0.05 were considered statistically significant. RESULTS: When compared with baseline ECoG, bolus i.v. remifentanil significantly increased the frequency of single spikes or repetitive spike bursts in the epileptogenic zone while suppressing activity in surrounding normal brain. CONCLUSIONS: During ES, remifentanil enhanced epileptiform activity during intraoperative ECoG. Such observations facilitate localization of the epileptogenic zone while minimizing resection of nonepileptogenic eloquent brain tissue. Although not specifically evaluated in this study, we speculate that remifentanil's short elimination half-life will facilitate neurologic function testing immediately after ES. Should this be the case, we envision remifentanil has the potential to supplant other opioids (e.g., alfentanil) during ECoG-guided ES.

Adult↗

PubMed1996

Blunt carotid injury in children.

Blunt carotid injury (BCI) is a rare entity which can have devastating neurologic consequences. Little has been reported on the mechanism of injury, presentation or management of these injuries in children. We present a series of 5 children with BCI. One patient died at presentation while the remainder developed delayed infarctions. Three surviving patients developed intracranial hypertension and required intracranial pressure (ICP) monitoring. Surgical resection of infarcted tissue was required to control ICP in 2 patients. All four surviving patients are impaired but ambulatory. We propose an aggressive management strategy for BCI aimed at early detection of deficit, early angiography, anticoagulation if appropriate, and active management of ischemia including hemodynamic treatment, ICP monitoring, and active use of medical and surgical means to monitor and control intracranial hypertension.

Adolescent↗

PubMed2003

Identifying potential surgical candidates in patients with evidence of bitemporal epilepsy.

PURPOSE: To determine which patients with evidence of medically refractory bitemporal epilepsy are potentially good candidates for surgical therapy. METHODS: We reviewed 42 adults with intractable seizures who were found to have bitemporal ictal onsets, based on scalp video-EEG long-term monitoring (LTM). All underwent invasive LTM before surgery. Surgical outcomes were classified as seizure free, >75% reduction in seizures, or <75% reduction in seizures, >or=1 year after resection. We related the following factors to outcome: (a). >75% preponderance of interictal scalp EEG discharges to one temporal region; (b). magnetic resonance imaging (MRI) findings; (c). lateralizing deficits on verbal or visual reproduction memory testing; and (d). memory failure with injection contralateral to side of surgery on Wada testing. RESULTS: Twenty-six (62%) of 42 patients had unilateral ictal onsets based on intracranial studies. Seizure freedom (occurring in 64% of this group), or >75% seizure reduction (found in 12% of subjects) occurred only when at least one of the following three factors was concordant with the side of surgery: preponderance of interictal scalp EEG discharges, unilateral temporal lesion on MRI, or lateralizing verbal or visual reproduction memory deficits on neuropsychological tests (p = 0.004). Seven subjects with bilateral ictal onsets based on intracranial studies had resections based on preponderance of seizures to one side, or other lateralizing noninvasive abnormality. Five of these (all of whom had >or=80% of seizures originating from one side) had >75% reduction in seizures. CONCLUSIONS: Invasive monitoring to pursue possible surgical therapy for patients with surface EEG evidence of bitemporal epilepsy may be justified only when some lateralizing feature is found in other noninvasive assessments.

Adolescent↗

PubMed1998

Epilepsy surgery in the first three years of life.

PURPOSE: Partial seizures in early postnatal life may be catastrophic and associated with poor long-term outcome. Epilepsy surgery can alleviate partial seizures in older children and adults, but there is little experience with surgical therapy in infancy apart from hemispheric epilepsy syndromes. METHODS: We analyzed the results of cortical resection to treat medically refractory partial epilepsy in 31 children (16 boys, 15 girls) aged <3 years (mean, 18.3 months). Subjects were included only if seizure relief was the primary indication for surgery. RESULTS: Follow-up of at least 1 year (mean, 4.6 years) in 26 patients revealed that 16 were seizure-free, 4 had >90% seizure reduction, and 6 had <90% reduction. There was no significant difference in seizure outcome between hemispherectomy/multilobar resections and lobar resections or temporal versus extratemporal resection. Seizure outcome was independent of the amount of cortex removed in nonlesional patients. Only the presence of a discrete lesion on preoperative neuroimaging correlated with a favorable outcome. Family perceptions of accelerated development in seizure-free patients were not confirmed on developmental assessment. CONCLUSIONS: We conclude that cortical resection often benefits very young children with catastrophic partial seizures, but does not guarantee enhanced neurological development. The location and extent of the excised cortex may not be critical as long as the entire epileptogenic region and lesion are removed.

Adult↗

PubMed1982

The localizing value of depth electroencephalography in 32 patients with refractory epilepsy.

Clinical seizure manifestations, physical examination, radiological studies, neuropsychological tests, and scalp and depth electroencephalographic (EEG) studies were done to localize seizure foci in 32 patients, 23 of whom have undergone surgery with more than one year of follow-up. Of 16 patients with unlocalized scalp EEGs, depth EEG detected a consistent focal seizure onset in 3. Of 15 patients with localized scalp EEGS, depth EEG revealed multiple foci in 3 and inaccurate localization of the focus by scalp EEG in 4. Therefore, localization by scalp EEG was inaccurate in 10 of 31 patients. When depth EEG revealed a consistent focal seizure onset and this localization was used to determine to surgical resection site, good to excellent results were obtained in 12 of 13 patients. When depth EEG revealed additional foci of seizure origin, surgical results were fair or poor in all patients. No other localizing criteria predicted depth EEG results or surgical success with such accuracy. Furthermore, some criteria, including neuropsychological tests and radiological abnormalities, were falsely localizing at times. Therefore, of the presently available localizing criteria, depth EEG appears to be the most accurate.

Adolescent↗

PubMed1997

Safety of intrahippocampal depth electrodes for presurgical evaluation of patients with intractable epilepsy.

PURPOSE: Intracerebral depth electrodes are used in preoperative evaluation of selected patients with intractable epilepsies. In spite of their usefulness, safety of depth electrodes is disputed, and the number of insertions is decreasing. This study examined retrospectively possible deleterious effects such as perioperative complications, induction of epileptogenesis, and neuropsychologic deficits. METHODS: Clinical course and neuroradiologic findings of 115 patients with bilaterally inserted longitudinal intrahippocampal depth electrodes (IDEs) were analyzed. Hippocampal resection specimens were examined histopathologically. To detect newly developed epileptogenic areas, EEG recordings, seizure control, and semiology after standardized resection procedures were compared between patients who received IDEs and those who did not. To demonstrate functional deficits caused by IDE insertion into an unaffected hippocampus of the speech-dominant hemisphere, changes of verbal learning and memory performances before and after right amygdalohippocampectomy were compared between patients evaluated with and without IDEs. RESULTS: Five significant complications without any permanent neurologic deficit were noted, and only one was specifically linked to IDE insertion. The tissue damage associated with the insertion was minimal and sharply circumscribed. No differences of seizure outcome after standardized resections were identified between patients with and without IDEs. In postoperative EEG recordings, there was no evidence of new epileptogenic areas. No verbal memory deficit caused by IDE implantation into the hippocampus of the speech-dominant hemisphere was detectable. CONCLUSIONS: Results indicate that it is safe to implant these IDEs in selected patients.

Adult↗

PubMed1993

MRI hippocampal volumes and memory function before and after temporal lobectomy.

We investigated the relationship between preoperative MRI hippocampal volumes and clinical neuropsychological memory test data obtained before and after temporal lobectomy and amygdalohippocampectomy for intractable epilepsy in 44 left (LTL) and 36 right (RTL) temporal lobectomy patients. In LTL patients, the difference (right minus left hippocampal volume) between hippocampal volumes (DHF) was significantly (p < 0.001) correlated (r = 0.61) with postoperative verbal memory change as measured by a delayed memory percent retention score from the Wechsler Memory Scale-Revised, Logical Memory subtest. DHF was also positively associated with postoperative memory for abstract geometric designs in LTL patients (r = 0.49, p < 0.005). Resection of a relatively nonatrophic left hippocampus was associated with poorer verbal and visual memory outcome. In RTL patients, larger right adjusted (for total intracranial volume) hippocampal volume was associated with decline in visual-spatial learning, but not memory, following surgery. MRI hippocampal volume data appear to provide meaningful information in evaluating the risk for memory impairment following temporal lobectomy.

Adult↗

PubMed1995

Use of frameless stereotaxy with location of electroencephalographic electrodes on three-dimensional computed tomographic images in epilepsy surgery.

Epileptiform activity corresponding to structural lesions was identified by three-dimensional (3D) imaging using computed tomographic (CT) scan data concurrently with scalp EEG electrodes. The electrodes, placed according to the international 10-20 system, were used to record interictal and ictal epileptogenic foci in eight patients. Electrodes placed where marked or moderate epileptiform activity was detected were replaced with markers detectable on CT. Scans with these markers on the skin were obtained and the data transferred to a 3D imaging system, and correlated with underlying cerebral structures. The reformatted images were used to assess the relation among intracranial lesions, brain surface structures, and epileptogenic zones depicted by the markers. The images help the surgeon plan a craniotomy with enough space for both lesionectomy and resection of the epileptogenic zone. In the central regions where crucial motor functions are located, the markers indicate the central fissure or postcentral gyrus. An intraoperative 3D frameless stereotactic pointing device helps in directing further examination of the epileptogenic zone. This system improves on the precision available through intraoperative electrocorticographic recording in the extratemporal lobes, thus avoiding only approximate excision of lesion and epileptogenic zone and enabling the neurosurgeon to perform epilepsy surgery with greater confidence.

Adolescent↗

PubMed2000

Relationships between the epileptic focus and hand area in central epilepsy: combining dipole models and anatomical landmarks.

OBJECT: When considering resection of epileptic generators near the central sulcus, it is essential to define the spatial relationship between the epileptic generator and the primary sensorimotor hand area. In this study, the authors assessed the accuracy of dipole modeling of electroencephalographic spikes and median nerve somatosensory evoked potentials (SSEPs) in defining this relationship preoperatively and noninvasively. METHODS: Epileptic spikes and SSEPs in patients with focal central area epilepsy were represented by dipole models coregistered onto global magnetic resonance images. In patients who underwent surgery, spike dipoles were also compared with findings of electrocorticography (ECoG) and with the resection area. To improve the accuracy of the dipole models, anatomical landmarks of the hand area were used to assess the error in SSEP dipole location, and this error measure was used to correct the location of spike dipoles. Five patients with central epilepsy were studied, three of whom underwent ECoG-guided surgical resections. The location of SSEP dipoles correlated well with anatomical landmarks of the primary sensory hand area. The relative position of the spike and SSEP dipoles correlated well with the patients' ictal symptoms, ECoG findings, and the location of the epileptic focus (as defined by the resection cavity in patients who became seizure free postoperatively). Corrected spike dipoles were located even closer to the resection cavity. CONCLUSIONS: The calculation of the relative location of spike and SSEP dipoles is a simple noninvasive method of determining the relationship between the primary hand area and an epileptic focus in the central area. The spatial resolution of this technique can be further improved using easily identifiable anatomical landmarks.

Adolescent↗

PubMed1990

Surgical treatment of epilepsy: three- to six-year follow-up of eleven patients with pharmacologically uncontrolled complex partial seizures.

There are an estimated 100,000 epileptic patients whose response to pharmacologic treatment is unsatisfactory. We report 11 patients with complex partial seizures who were selected for surgical treatment after adequate trials on antiepileptic medication failed. Immediate improvement-no further seizures or reduced frequency of occurrence and severity-was sustained at 3- to 6-year follow-up, and 7 patients were driving, 10 were working, and all were enjoying a better quality of life. Likely candidates for temporal lobectomy or resection of epileptogenic cerebral cortical lesions are those with a single focus of seizure discharge on video-EEG monitoring. If this focus is remote from language or motor areas, and if there is no interference with memory and recall after intracarotid amobarbital injection ipsilateral to the intended surgery, good results can be expected in the majority of such patients. We discuss patient selection and evaluation, and encourage surgical treatment where the indications can be established.

Adolescent↗

PubMed1988

A combined retroauricular and preauricular transpetrosal-transtentorial approach to clivus meningiomas.

A combined retroauricular and preauricular transpetrosal-transtentorial approach is described for the resection of meningiomas arising from the clivus. Via radical mastoidectomy the sigmoid sinus is exposed down to the jugular bulb, and via the transmastoideal-subtemporal approach the retroauricular petrosal bone, 1 cm in depth from the petrosal ridge, and the roof of the internal auditory meatus are removed, the middle ear and fallopian canal being left intact. Additionally, via a transzygomatic-subtemporal approach the preauricular petrosal bone is removed anteriorly up to the petrosal tip and laterally as far as the petrosal portion of the internal carotid artery, while the cochlea is preserved. By this means, the triangular portion of the posterior petrosal dura mater, delimited by the superior petrosal sinus, inferior petrosal sinus, and sigmoid sinus, is well exposed extradurally. By opening the subtemporal and posterior petrosal dura mater, in combination with a tentoriotomy, adequate exposure of the basilar artery, vertebral arteries, ventral and lateral portions of the brainstem, and cranial nerves is achieved with minimal retraction of the temporal lobe and cerebellum.

Cranial Fossa, Posterior↗