Computer-assisted image-guided orbit surgery.

PURPOSE: Modern stereotaxy utilizes preoperative computed tomography (CT) and magnetic resonance imaging (MRI) to provide accurate localization information which can be very helpful in orbital surgery. The purpose of this report is to evaluate the usefulness of stereotactic surgery and application of this procedure in the orbit. METHODS: Interventional case series of three patients with orbital tumors. All patients had tumor resection with the utilization of two frameless stereotactic systems: Cygnus and Stealth Station. RESULTS: The applications of image-guided stereotactic surgery proved to be beneficial in three extensive orbital tumors, including optic nerve glioma, recurrent pleomorphic adenoma of lacrimal gland, and secondary orbital meningioma. CONCLUSIONS: The interactive nature of image guidance can be useful in orbital surgery to orient the surgeon to the exact location within the surgical field and to determine the tumor margins.

[What is the role of neuropsychological testing in the investigation and management of pharmacologically intractable partial epilepsy?]. / Quelle est la place du bilan neuropsychologique dans la prise en charge des patients souffrant d'une épilepsie partielle pharmaco-résistante?

Neuropsychological testing is an integral part of investigation and management of pharmacologically intractable epilepsy. Patients often complain of cognitive difficulties, in particular memory disturbances. A review of the literature demonstrates that correlations between subjective memory difficulties and objective memory deficits are often poor with mood correlating more consistently with subjective complaints. Nevertheless, objective memory difficulties are often found, especially in patients with temporal lobe epilepsy. Many factors can contribute to cognitive difficulties in patients with pharmacoresistant partial epilepsy. These include brain pathology that may be the cause or the consequence of chronic seizures (or both), physiological brain dysfunction due to epileptic activity and effects of antiepileptic medications. We review some of the abundant relevant literature. Neuropsychological evaluation is routinely used in pre-surgical evaluations of patients and cognitive dysfunction has some degree of correlation with lateralization and localization of epileptic activity, thus helping to determine a surgical strategy. The goal of seizure control is tempered with an assessment of the potential cognitive loss resulting from resective surgery. A number of studies have addressed postoperative neuropsychological findings and it is universally recognized that patients who have high levels of cognitive functioning in the areas targeted for resection (for instance verbal memory in dominant temporal lobe) show the greatest functional loss following surgery. More selective surgery probably results in some level of preservation of cognitive function.

[What is the current role of a Wada test in the pre-surgical work-up of pharmacologically intractable epilepsy in adults?]. / Quelle est la place du test de Wada dans le bilan préchirurgical des épilepsies pharmaco-résistantes chez l'adulte?

Juhn Wada developed a test while in Montreal designed to definitively confirm hemispheric lateralization of speech in candidates for surgical treatment of epilepsy. By unilateral intra-carotid administration of a bolus of a general anesthetic, classically sodium amobarbital, function can be tested in the non-injected hemisphere, while the injected side is dysfunctional. The test has been expanded to test memory functions in the hemisphere (temporal lobe) contralateral to expected surgery (memory reserve) in the hope of contra-indicating surgery that may result in global amnestic syndromes (patient HM). Conversely, risk of material-specific memory loss following surgery can be assessed by testing memory in the hemisphere/temporal lobe to be operated ("functional adequacy"). Memory dysfunction, when concordant with EEG seizure onset and chosen side of temporal lobe surgery has also been shown to correlate with favourable post-operative seizure outcome. Nevertheless, the test remains invasive, requiring an angiogramme. Non-invasive alternatives such as fMRI and PET and their reported reliability compared to a Wada test are discussed. A world-wide shortage of amobarbital has led to the use of some other anesthetic agents. Overall, the indications for the test and the manner in which it is performed vary greatly from one institution to the next. It is used almost systematically in some institutions and very rarely in others. Future perspectives are discussed.

Frontal sinus osteoma associated with cerebral abscess formation: a case report.

BACKGROUND: Osteomas of the paranasal sinuses rarely lead to intracranial manifestations. We present an unusual case of a frontal sinus osteoma leading to intracerebral abscess formation. CASE DESCRIPTION: A 51-year-old Hispanic man presented with increasing frontal headaches, new onset seizure, lethargy, global dysphasia, and unilateral hemiparesis. CSF studies demonstrated mild pleocytosis. Neuroradiological studies revealed an opacity filling the left frontal sinus, as well as a ring-enhancing mass with surrounding edema in the left frontal lobe. The patient was surgically treated with a left frontal osteoplastic craniotomy and removal of the abscess and bony mass. Intraoperative cultures were positive for Streptococcus pneumoniae. Pathology revealed bony tumor consistent with osteoma. The patient's neurological status improved to baseline after surgery. CONCLUSION: The frontal sinus osteoma was associated with rapid development of a frontal lobe abscess, requiring emergent surgical debridement. Although rare, intracerebral manifestations should be considered and expected as a cause of new neurological deficits in the presence of paranasal sinus osteoma.

Primary myxoma of the temporal bone in a 17-year-old boy: case report.

OBJECTIVE AND IMPORTANCE: Only two cases of primary intracranial myxomas have been described previously in the literature: one patient had a primary intracranial myxoma in the pituitary fossa, and the other patient's myxoma was located in the posterior fossa. CLINICAL PRESENTATION: A rare case of primary myxoma of the temporal bone in a 17-year-old boy is described. The patient presented with a history of progressive left-sided hearing loss and increasing headaches of a few months' duration. INTERVENTION: An initial draining procedure in the left ear revealed extant mucous material, and further investigation showed a large calcified lesion involving the petrous and temporal bones and filling the middle fossa. At surgery, a large mucoid-appearing tumor was removed. The tumor pathology revealed a primary myxoma with bone and meningeal involvement. No clinical or histopathological evidence that it was a metastatic lesion was found. CONCLUSION: The features of myxomas on computed tomographic and magnetic resonance imaging, the histopathology, and surgical considerations are discussed.

Delayed epidural hematoma: presentation in a pediatric patient.

Epidural hematomas remain at the pinnacle of neurosurgical emergencies, representing approximately 3% to 8% of all serious head injuries. Mortality from this entity is usually prevented once the diagnosis is clear. Although readily recognized on non-contrast head CT, the occasional patient may go on to develop a clinically significant hematoma after an initial negative CT. This phenomenon is appropriately termed delayed epidural hematoma. We present a case in which a 3-year-old boy developed a large epidural hematoma, which was not evident until the second CT, several hours after the injury. We feel that maintaining a high clinical suspicion, coupled with a low threshold for CT scanning, is the key to morbidity prevention in this illness.

Peri-insular hemispherotomy: surgical principles and anatomy.

THE NATURE OF functional hemispherectomy continues to be misunderstood despite its 20-year history. Recently, we introduced the concept of peri-insular hemispherotomy, a functional hemispherectomy with minimal brain removal (9, 21). To avoid additional confusion, a detailed neuroanatomic account of this operation, which has been performed in 11 patients, is presented. The name of the operative variant presented derives from the central importance of the exposure of the insula as the first surgical landmark. Incising along the circular sulcus that surrounds the insula not only allows access to the dilated ventricular system but also disrupts the entire internal capsule. A parasagittal callosotomy is performed from within the lateral ventricle by incising the medial ventricular roof. Projections through the anterior commissure are disrupted at the time of radical amygdalar resection. The posterior hippocampus need not be radically removed, because its posterior transsection disconnects it. Overall, peri-insular hemispherotomy can be viewed as a radical hemispheric tractotomy, resulting in a completely disconnected hemisphere. Advantages include shorter operative times, a less stormy postoperative course, and better anatomic preservation of the operated hemisphere, thus presumably reducing long-term complications.

Automated EEG monitoring in defining a chronic epilepsy model.

There has been a recent surge of interest in chronic animal models of epilepsy. Proper assessment of these models requires documentation of spontaneous seizures by EEG, observation, or both in each individual animal to confirm the presumed epileptic condition. We used the same automatic seizure detection system as that currently used for patients in our institution and many others. Electrodes were implanted in 43 rats before intraamygdalar administration of kainic acid (KA). Animals were monitored intermittently for 3 months. Nine of the rats were protected by anticonvulsants [pentobarbital (PB) and diazepam (DZP)] at the time of KA injection. Between 1 and 3 months after KA injection, spontaneous seizures were detected in 20 of the 34 unprotected animals (59%). Surprisingly, spontaneous seizures were also detected during the same period in 2 of the 9 protected animals that were intended to serve as nonepileptic controls. Although the absence of confirmed spontaneous seizures in the remaining animals cannot exclude their occurrence, it indicates that, if present, they are at least rare. On the other hand, definitive proof of epilepsy is invaluable in the attempt to interpret pathologic data from experimental brains.