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Comparison of depth and subdural electrodes in recording temporal lobe seizures.

Intracranial EEG recording is often required to identify an area of the brain for resective surgery for intractable epilepsy. We simultaneously compared bilaterally placed depth and limited subdural electrode EEG to determine the most effective method of recording seizures from the temporal lobes. Localized complex partial seizures usually appeared earlier in hippocampal depth electrodes and spread later to subdural recording sites. In 3 patients, hippocampal recordings showed localized seizure origin but subdural recording was nonlocalizing due to rapid bilateral seizure propagation. In 1 patient with nonlocalized seizures presumably of extratemporal origin, subdural electrodes incorrectly lateralized seizure origin to a temporal lobe. Auras and subclinical seizures detected by depth electrode recording were often not evident with subdural electrodes. We conclude that EEG recording with hippocampal depth electrodes correctly identifies and lateralizes temporal lobe seizures more often than with limited subdural electrodes.

Adolescent↗

Functional and anatomic correlates of two frequently observed temporal lobe seizure-onset patterns.

Intracranial depth electrode EEG records of 478 seizures, recorded in 68 patients undergoing diagnostic monitoring with depth electrodes, were evaluated to investigate the correlates of electrographic onset patterns in patients with temporal lobe seizures. The seizure onsets in 78% of these patients were identified as either hypersynchronous onsets, beginning with low-frequency, high-amplitude spikes, or low-voltage fast (LVF) onsets, increasing in amplitude as the seizure progressed. The number of patients (35) having hypersynchronous seizure onsets was nearly twice that of patients (18) having LVF onsets. Three major differences were seen among patients with the two seizure-onset patterns. When compared with patients having LVF onsets, patients with hypersynchronous seizure onsets had a significantly greater probability of having (1) focal rather than regional seizure onsets (p < 0.01), (2) seizures spreading more slowly to the contralateral mesial temporal lobe (p < 0.003), and (3) cell counts in resected hippocampal tissue showing greater neuronal loss (p < 0.001). The results provide evidence that the most frequent electrographic abnormality associated with mesial temporal seizures is local hypersynchrony, a condition associated with major neuronal loss in the hippocampus. The results also indicate that LVF seizure onsets more frequently represent widely distributed discharges, which interact with and spread more rapidly to surrounding neocortical areas.

Adolescent↗

[Hippocampal hemosiderin deposit due to large pituitary adenoma presenting temporal lobe epilepsy--a case report].

There have been reports of epilepsy associated with pituitary adenoma, but the epileptogenic zone and its histopathology have never been sufficiently described. We report a case of pituitary adenoma complicated by temporal lobe epilepsy, in which the epileptogenic focus was identified, resected, and examined histopathologically. The patient was a 38-year-old man on bromocriptine therapy for a huge pituitary adenoma (prolactin-producing) since 1985. He also had a history of temporal lobe epilepsy since 1989. CT images in 1985 revealed the tumor extending to the supra- and left para-sellar region. MR images in 1995 showed a significant decrease in the size of the tumor and a signal void area that was interpreted as a hemosiderin deposit in the left mesial temporal lobe. Ictal EEG demonstrated that seizure discharges were elicited at the left sphenoidal electrode and propagated to the both temporal lobes. Interictal SPECT revealed a local area of hypoperfusion in the left fronto-parietal lobe. An epileptogenic focus in the left mesial temporal lobe was diagnosed on the basis of the above examinations. The patient was treated by left anterior temporal lobectomy with partial hippocampectomy. Hemosiderin deposition in the hippocampus was suspected during surgery. Histopathological examination showed pyramidal cell loss and gliosis in the left hippocampus and confirmed the presence of hemosiderin in the CA1 region. The hemosiderin deposition in the hippocampus was inferred to have resulted from intratumoral hemorrhage due to bromocriptine therapy, and it may have caused the temporal lobe epilepsy in this patient. The outcome of surgery was freedom from seizures for eight months. Intra-tumoral hemorrhage in mesial temporal structures must be borne in mind as one of the epileptogenic mechanisms in pituitary adenoma, especially in cases in which hemosiderin is detected on MR images.

Adenoma↗

Delayed radiation necrosis of the brain contralateral to original tumor.

In a 23-year-old man, radiation necrosis developed in the left hemisphere after radiation of a right-sided intracranial tumor. Since normal tissue had to be resected around the tumor, the contralateral temporal lobe received the highest cumulative radiation dose for brain tissue. This report underscores the need for careful reconstruction of the radiation isodose distribution when considering the differential diagnosis of postradiation brain lesions.

Adult↗

A novel mechanism underlying drug resistance in chronic epilepsy.

The development of resistance to pharmacological treatment is common to many human diseases. In chronic epilepsy, many patients develop resistance to anticonvulsant drug treatment during the course of their disease, with the underlying mechanisms remaining unclear. We have studied cellular mechanisms underlying drug resistance in resected hippocampal tissue from patients with temporal lobe epilepsy by comparing two groups of patients, the first displaying a clinical response to the anticonvulsant carbamazepine and a second group with therapy-resistant seizures. Using patch-clamp recordings, we show that the mechanism of action of carbamazepine, use-dependent block of voltage-dependent Na(+) channels, is completely lost in carbamazepine-resistant patients. Likewise, seizure activity elicited in human hippocampal slices is insensitive to carbamazepine. In marked contrast, carbamazepine-induced use-dependent block of Na(+) channels and blocked seizure activity in vitro in patients clinically responsive to this drug. Consistent with these results in human patients, we also show that use-dependent block of Na(+) channels by carbamazepine is absent in chronic experimental epilepsy. Taken together, these data suggest that a loss of Na(+) channel drug sensitivity may constitute a novel mechanism underlying the development of drug-resistant epilepsy.

Adult↗

Epilepsy surgery in the posterior cortex.

Fourteen (74%) of 19 patients obtained a significant reduction in seizures after posterior corticectomy; 6 (32%) were seizure-free over a median follow-up of 3.7 years (range, 1 to 14 years). Surgery included limited resections of the occipital lobe in 16 patients, posterior temporal region in 11, and posterior portion of parietal lobe in 7. Surgical failure related to probable multiple areas of epileptogenesis (4 patients), or limited resections (2 patients) to preserve visual fields (2 patients) and to avoid dyslexia (1 patient). Of 14 patients without a complete hemianopia preoperatively, 6 (43%) developed a new or increased visual field deficit, 2 (14%) of which were hemianopia. Four (36%) of 11 occipital lobe resections resulted in a new or increased visual field deficit: quadrantanopia in 3 and hemianopia in 1. Visual phenomena were the most common initial ictal symptoms, occurring in 13 (68%) of the 19 patients. Twelve patients had complex partial seizures: in 2, always without warning; in 7, always following an aura, usually visual; and in 3 patients, with or without warning. Scalp electroencephalography identified the origin of most recorded seizures in 12 (63%) of the 19 patients. A principal interictal spike focus appeared in 15 patients (79%), and always correlated with the epileptogenic lobe as defined by scalp and/or subdural-recorded seizures (14 patients) or by clinical analysis and computed tomography (1 patient).

Adolescent↗

Klüver-Bucy syndrome in man: experiences with posttraumatic cases.

After the original description of characteristic behavioral changes in rhesus monkeys after bilateral resection of major portions of the temporal lobes by Klüver and Bucy in 1937 [11], similar syndromes have repeatedly been reported in human pathology. The present paper is based on clinical analysis of 40 cases of traumatic apallic syndrome (TAS), 30 of whom developed a complete or partial Klüver-Bucy syndrome during recovery. The dynamics in the development of a Klüver-Bucy syndrome during remission of a TAS are analyzed. The delineation between a pre-stage, full-stage and remission-stage of the Klüver-Bucy syndrome is suggested.

Adolescent↗

Comparison of valproate concentrations in human plasma, CSF and brain tissue after administration of different formulations of valproate or valpromide.

The concentration of valproate was measured in plasma, CSF and brain tissue of patients who underwent resective surgical treatment because of severe temporal lobe epilepsy after pretreatment with either a sustained release formulation of valproate (Depakine Chrono; 5 patients), the conventional formulation of valproate (Depakine; 6 patients) or valpromide (Depamide; 2 patients). With a mean serum value for all 13 patients of 32.3 micrograms/g valproate, the mean brain/serum ratio was 15.1% (SD 6.1%). The valproate concentration of the hippocampus was significantly higher than that of the amygdala and patients who had the sustained release formulation had significantly higher valproate concentration in the CSF and in the hippocampal formation than those patients who had the conventional valproate. Since a few patients had tumors, whereas others had varying degrees of gliosis, it cannot be ruled out that these differences are the result of different histopathological conditions with related differences in blood-brain barrier functions.

Adolescent↗

Novel expression of AMPA-receptor subunit GluR1 on mossy cells and CA3 pyramidal neurons in the human epileptogenic hippocampus.

Previous immunocytochemical investigations performed in our laboratory on the human hippocampus surgically resected for the treatment of mesial temporal lobe epilepsy (MTLE) have demonstrated an increased expression of the AMPA-receptor subunit GluR1 on neurons in the hilus and area CA3. Light microscopically, many of these neurons exhibited peculiar filamentous extensions and grape-like excrescences that protruded from their somata and proximal dendrites, suggesting that these neurons may be mossy cells and CA3 pyramidal neurons, respectively. The present electron microscopic study was carried out to further characterize these cells. The filamentous extensions were identified as dendrites from which spines often protruded, and the grape-like excrescences represented clusters of closely associated dendrites and spines. A variety of synapses were formed by the GluR1-positive profiles. These arrangements ranged from simple contacts between a single unlabelled axon terminal and a single labelled postsynaptic element, to complex contacts involving multiple unlabelled axon terminals and labelled postsynaptic elements. Many of the axon terminals involved in these arrangements were mossy fibre boutons. Thus, a large proportion of the GluR1-positive neurons were identified as hilar mossy cells and CA3 pyramidal neurons, cells hitherto thought to be absent or greatly reduced in the MTLE hippocampus. Taken together, these data suggest the presence of a highly efficient excitatory circuit involving AMPA receptors, mossy cells and CA3 pyramidal neurons in the sclerotic hippocampus. Such a circuit could be critically involved in the genesis and maintenance of temporal lobe epilepsy.

Dendrites↗

Glioneuronal tumor with neuropil-like islands.

Mixed glioneuronal neoplasms are relatively uncommon tumors in the central nervous system. Recently, an unusual glioneuronal tumor arising in adults marked histologically by neuropil-like islands was described. We present a similar case arising in a 23-year-old woman who presented with headaches and seizures and on imaging studies was noted to have a frontal-temporal lobe mass. The patient underwent partial resection of the tumor, which histologically resembled anaplastic astrocytoma, and received a course of radiation therapy and chemotherapy. Increasing seizure frequency and expanding size on neuroimaging prompted a re-excision of the tumor. The second resection was marked by islands of tissue resembling gray matter with slightly atypical neuronal and glial cells situated in the white matter. These islands stained positively with synaptophysin and did not stain with glial fibrillary acid protein. Mild vascular proliferation and moderate nuclear pleomorphism also characterized the tumor. Areas of necrosis were not noted. A MIB-1 labeling index of 18.1% was noted. P53 immunoreactivity was observed in approximately 40% of tumor cell nuclei. This lesion is felt to represent a clinically aggressive glioneuronal neoplasm with an unusual and distinctive histologic phenotype. HUM PATHOL 31:1435-1438.

Adult↗

Sphenoidal and cavernous sinus resection for tumor.

Malignant neoplasms as well as those with an aggressive locally invasive character involving the sphenoid sinus have been considered heretofore to be inoperable and incurable. Because of fear of entering the cavernous sinus, the proximity of the internal carotid artery laterally and the optic chiasm superiorly as well as the middle fossa contents, these patients were relegated to palliative regimens of irradiation and chemotherapy. As methods have been developed of managing hemorrhage from the cavernous sinus, exposure and control or bypass of the internal carotid artery and combined subcranial and intracranial resection, the frontiers of surgery in the sphenoid sinus have been advanced. We have resected eight patients with tumors involving the sphenoid sinus in whom the walls of the sinus were exenterated, portions of the cavernous sinus removed, the internal carotid artery skeletonized, anterior and middle fossa dura resected, and in a few the temporal lobe was excised. Follow-up ranges from six years to 10 months. There have been no perioperative deaths; one patient succumbed to general inanition with locally recurrent tumor at four months; the rest are all alive and well without evidence of tumor, with the exception of one patient. This patient has a local recurrence anteriorly from an inadequate margin due to a technical error, but there is no recurrence in the sphenoid sinus, the cavernous sinus or the middle cranial fossa.

Cavernous Sinus↗

[A case of intra- and extracranial development of a craniofacial teratoma. Excision during the neonatal period through a mixed cranio-facial approach (author's transl)].

A newborn infant was found to have a laterocervical swelling invading the floor of the mouth. Exploration of the mass revealed that there was invasion of the left side of the soft palate and, more particularly, a prominence in the temporal fossa causing an obvious cranio-facial asymmetry. Radiological and neuroradiological investigations demonstrated the presence of a tumor destroying the greater wing of the sphenoid, invading the left side of the temporal fossa, extending into the pterygomaxillary fossa up to the soft palate, and finally appearing exteriorly in the sub-maxillary region. Excision was carried out in the neonatal period because of the poor tolerance from the neurological point of view. A wide cranio-facial approach was first employed, enabling resection of the point of the temporal lobe, clogging of the cranial base, and excision as one piece of the complete palatocervical extension of the tumor. Follow-up one year later showed that the child possessed excellent neurological development and there was no sign of recurrence of the mass. A review of the published literature showed the extremely rare nature of this type of localization of cervicofacial teratomas (5 other cases have been reported). The surgical procedures and the problems encountered are discussed as well as the indications for excision, based on results obtained in this case and those previously reported. The etiology and anatomy are also reviewed in order to establish their true significance in the case of congenital cranio-facial tumors.

Brain Neoplasms↗

[Comparison of valproate level in human plasma, cerebrospinal fluid and brain tissue following administration of various preparations of valproate and valpromide].

The concentration of valproate was measured in plasma, CSF and brain tissue of patients who underwent resective surgical treatment because of severe temporal lobe epilepsy after pretreatment with either a sustained release formulation of valproate (Depakine Chrono: 5 patients), the conventional formulation of valproate (Depakine: 6 patients) or valpromide (Depamide: 2 patients). With a mean serum value for all 13 patients of 32.3 micrograms/g valproate, the mean brain/serum ratio was 15.1% (SD 6.1%). The valproate concentration of the hippocampus was significantly higher than that of the amygdala, and patients who had the sustained release formulation had significantly higher valproate concentration in the CSF and in the hippocampal formation than those patients who had the conventional valproate. Since a few patients had tumors, whereas others had varying degrees of gliosis, it cannot be ruled out that these differences are the result of different histopathological conditions with related differences in blood-brain barrier functions.

Adolescent↗

Pathological changes in surgically resected angiographically occult vascular malformations after radiation.

OBJECTIVE: The goal of this study was to evaluate the pathological changes associated with radiation treatment (stereotactic radiosurgery or conventional irradiation) of angiographically occult vascular malformations (AOVMs). METHODS: Eleven patients underwent surgical resection of an AOVM in the mesial temporal lobe, brain stem, thalamus, or basal ganglia after previous radiation treatment. The indications for surgery were recurrent symptomatic bleeding from the lesion in 10 patients and recurrent intractable seizures in 1 patient. Radiation was used as the initial therapy because the risk of surgical resection was deemed too high. Three patients received conventional radiation therapy of 3000 to 5400 rads at an outside institution. One patient received radiosurgery with the gamma knife at another institution using a dose of 15 Gy to the margin. The remaining 7 patients received stereotactic radiosurgery with a helium-ion particle beam. The dose range was from 18 to 26 Gy equivalents. The interval from radiation to surgical resection ranged from 1 to 10 years, with a mean of 3.5 years. These lesions were compared with 10 nonirradiated cavernous malformations. RESULTS: One irradiated lesion was identified pathologically as a true arteriovenous malformation despite being angiographically occult. This lesion did not demonstrate significant changes in the vasculature but did have radiation necrosis of the surrounding brain 5 years after 25 Gy equivalents of helium-ion radiosurgery. Two other specimens were too small to identify the type of vascular malformation adequately. Of the remaining eight malformations identified as cavernous malformations, six showed a combination of marked fibrosis of the vascular channels, fibrinoid necrosis, and ferrugination. However, the fibrinoid necrosis was the only finding unique to the irradiated lesions compared with nonirradiated controls. All the irradiated lesions still had patent vascular channels; none were completely thrombosed. CONCLUSION: Radiosurgery or conventional radiation therapy did not cause histologic vascular obliteration in intracranial AOVMs evaluated 1 to 10 years (mean 3.5 yr) after radiation delivery. It should be recognized that these patients are irradiation failures who may not be representative of all irradiated patients. However, recurrent bleeding from AOVMs may relate to poor radiation response in some patients.

Cerebral Angiography↗

Temporal lobe epilepsy surgery in childhood: rationale for greater use.

Anterior temporal resection may effectively relieve therapy-resistant seizures in children and give social, psychological and economic benefits. Epidemiological and prognostic data demonstrate that this is an under-utilised procedure: although an estimated 677 Ontario children per year would be candidates for anterior temporal resection, only 18 were performed in a 12 month period.

Child↗

Postoperative radiographic findings following acoustic neuroma removal.

This paper assesses the radiographic findings seen on early postoperative CT following acoustic neuroma resection. CT head scans were routinely obtained from 86 patients within 24 hours of tumor resection via a translabyrinthine or retrosigmoid approach. Repeat CT scans were performed in those patients with abnormal clinical symptoms. The abnormalities seen on postoperative CT included cerebellar hematoma (nine patients), cerebral and/or cerebellar infarction (six patients), CSF leak at the incision (two patients), subdural hematoma (two patients), hydrocephalus (one patient), and residual acoustic neuroma (two patients). An unexpected CT finding was ipsilateral temporal lobe lucency, suggesting venous edema, ischemia, and/or infarction in 16% (14/86) of patients. Overall, the clinical complication rate was 8%, and subclinical CT abnormalities were seen in 17% of patients. Temporal lobe venous edema, ischemia, or infarction is a complication of translabyrinthine resection of acoustic neuroma and is thought to be due to obstruction of an inferior temporal lobe draining vein. Some cases may be related to intraoperative interruption of the superior petrosal sinus or petrosal vein, and/or coagulation of the sigmoid sinus dural margins, interruption of an inferior temporal vein, or venous hypotension. Care in dealing with the superior petrosal and sigmoid sinuses at surgery is needed.

Journal Article↗

Predictive value of electrocorticography in epilepsy patients with unilateral hippocampal sclerosis undergoing selective amygdalohippocampectomy.

The purpose of this study was to evaluate the predictive value of intraoperative electro-corticography (ECoG) in patients with unilateral hippocampal sclerosis (HS) undergoing transsylvian selective amygdalohippocampectomy (sAHE). ECoG was recorded before and after resection in 22 patients with medication-resistant mesial temporal lobe epilepsy. The sAHE was performed, regardless of ECoG findings. ECoG findings recorded from the mesiobasal temporal lobe (MTL) and lateral temporal lobe (LTL) before and after the sAHE were correlated with seizure outcome 12 months later. Ten patients had right-sided and 12 left-sided HS. Average age was 37.1 years. Pre-resection spikes were restricted to the MTL in 11 patients and to the LTL in one. In three patients spikes were recorded from MTL and LTL and in seven no spikes were recorded before the resection. Fifteen patients (68%) remained completely seizure-free and 19 (86%) were in Engel's class I post-operatively. Patients with pre-resection spikes restricted to the MTL (n = 11) remained seizure-free more frequently (9/11, 82%) compared with other patients (6/11, 55%; P = 0.36). Pre-resection ECoG may be helpful in the prediction of seizure outcome in patients undergoing sAHE for mesial temporal lobe epilepsy. A larger study including more than 100 patients is needed to determine the predictive value of ECoG in patients with mesial temporal lobe epilepsy.

Adolescent↗

Seizures with onset in the sensorimotor face area: clinical patterns and results of surgical treatment in 20 patients.

It is not generally appreciated that intractable seizures involving the face area are amenable to surgical treatment. Twenty patients with onset of sensorimotor seizures in the face area of the pre- and postcentral gyri have been studied and surgically treated since 1948. Seizures started in the face, tongue, or throat, followed by diverse patterns depending on spread of seizure activity. Two patients had epilepsia partialis continua; 6 had either tonic or atonic drop attacks. All patients had pre- and postcentral face area resections, 12 in the dominant hemisphere. In addition, 3 had more extensive postcentral removal, 7 had temporal lobe, and 4 had small separate or contiguous frontal or parietal resection. Because the seizures were not sufficiently reduced by the first operation, 6 required reoperation; 4 of these patients had residual epileptiform activity on electrocorticogram (ECoG) after the first resection. Three patients had new neurologic signs that did not return to the preoperative level, but in 2 of them the deficit related mainly to higher resection in the central area. All but 2 of these 20 patients had at least moderate seizure reduction. Corticectomy can be performed for treatment of seizures arising in the lower central area and usually does not lead to significant permanent neurologic deficit.

Adolescent↗