Migration of intradural epidermoid matrix: embryologic implications.

The migratory behavior of acquired cholesteatoma matrices (those arising from the tympanic membrane) has been described previously. This tissue is derived embryologically from the first branchial groove and represents the only migratory epithelium arising from the branchial groove system. If the matrix from a cerebellopontine angle (CPA) epidermoid tumor exhibits migratory behavior similar to that of acquired cholesteatomas, a first branchial groove site of origin for CPA epidermoids would be supported. Intradural CPA epidermoid cells were grown in alpha-minimum essential medium. The cultures were examined daily, and cell mass migration rates were measured. It was observed that intradural epidermoid tumor matrix harvested from the CPA exhibited migration in vitro. Its migratory properties were indistinguishable from those of acquired cholesteatomas, which are embryologically derived from the first branchial groove. These data support the theory that purely intradural epidermoids are derived from cells of the first branchial groove.

Localization of language-specific cortex by using magnetic source imaging and electrical stimulation mapping.

OBJECT: In this paper the authors demonstrate the concordance between magnetic source (MS) imaging and direct cortical stimulation for mapping receptive language cortex. METHODS: In 13 consecutive surgical patients, cortex specialized for receptive language functions was identified noninvasively by obtaining activation maps aided by MS imaging in the context of visual and auditory word-recognition tasks. Surgery was then performed for treatment of medically intractable seizure disorder (eight patients), and for resection of tumor (four), or angioma (one). Mapping of language areas with cortical stimulation was performed intraoperatively in 10 patients and extraoperatively in three. Cortical stimulation mapping verified the accuracy of the MS imaging-based localization in all cases. CONCLUSIONS: Information provided by MS imaging can be especially helpful in cases of atypical language representation, including bihemispheric representation, and location of language in areas other than those expected within the dominant hemisphere, such as the anterior portion of the superior temporal gyrus, the posteroinferior portion of the middle temporal gyrus, the basal temporal cortex, and the lateral temporooccipital cortex.

Magnetoencephalographic mapping of the language-specific cortex.

OBJECT: In this paper the authors introduce a novel use of magnetoencephalography (MEG) for noninvasive mapping of language-specific cortex in individual patients and in healthy volunteers. METHODS: The authors describe a series of six experiments in which normative MEG data were collected and the reliability, validity, and topographical accuracy of the data were assessed in patients who had also undergone the Wada procedure or language mapping through intraoperative cortical stimulation. CONCLUSIONS: Findings include: 1) receptive language-specific areas can be reliably activated by simple language tasks and this activation can be readily recorded in short MEG sessions; 2) MEG-derived maps of each individual are reliable because they remain stable over time and are independent of whether auditory or visual stimuli are used to activate the brain; and 3) these maps are also valid because they concur with results of the Wada procedure in assessing hemispheric dominance for language and with the results of cortical stimulation in identifying the precise topography of receptive language regions within the dominant hemisphere. Although the MEG mapping technique should be further refined, it has been shown to be efficacious by correctly identifying the language-dominant hemisphere and specific language-related regions within this hemisphere. Further development of the technique may render it a valuable adjunct for routine presurgical planning in many patients who harbor tumors or have epilepsy.

Atypical temporal lobe language representation: MEG and intraoperative stimulation mapping correlation.

Functional brain imaging techniques hold many promises as the methods of choice for identifying areas involved in the execution of language functions. The success of any of these techniques in fulfilling this goal depends upon their ability to produce maps of activated areas that overlap with those obtained through standard invasive procedures such as electrocortical stimulation. This need is particularly acute in cases where active areas are found outside of traditionally defined language areas. In the present report we present two patients who underwent mapping of receptive language areas preoperatively through magnetoencephalography (MEG) and intraoperatively through electrocortical stimulation. Language areas identified by both methods were located in temporoparietal regions as well as in less traditional regions (anterior portion of the superior temporal gyrus and basal temporal cortex). Importantly there was a perfect overlap between the two sets of maps. This clearly demonstrates the validity of MEG-derived maps for identifying cortical areas critically involved in receptive language functions.

Acoustic neuromas: results of current surgical management.

OBJECTIVE: In this article, we review the surgical outcomes of 179 patients with acoustic neuromas. METHODS: Most of the tumors (84%) were operated on using a retrosigmoid, transmeatal approach. A transpetrosal, retrosigmoid approach was used in 10% of the patients, most of whom had large tumors. The translabyrinthine (4%) and transmastoid, transpetrosal, partial labyrinthectomy approaches (2%) were used selectively. The operative approaches are discussed. Tumors were categorized according to their cerebellopontine angle dimensions as small (< 2 cm), medium (2.0-3.9 cm), and large (> or = 4 cm). RESULTS: House-Brackmann evaluation of postoperative facial nerve function revealed excellent results (Grade I or II) in 96% of small tumors, 74% of medium tumors, and 38% of large tumors. A fair postoperative function (Grade III or IV) was achieved in 4% of small tumors, 26% of medium tumors, and 58% of large tumors. Functional hearing preservation, defined as Gardner-Robertson Class I or II, was achieved in 48% of small tumors and 25% of medium tumors. Hearing was not preserved in any of the three patients with large tumors in whom hearing preservation was attempted. Treatment complications consisted mainly of cerebrospinal fluid leakage (15% of the patients). The majority of the patients who experienced cerebrospinal fluid leakage were treated successfully with lumbar spinal drainage; only four patients (2% of the total group) required subsequent surgery for correction of cerebrospinal fluid leakage. There were two deaths (1%) in this series. One death occurred as the result of myocardial infarction and the other as the result of severe obstructive lung disease. One patient sustained disability because of cerebellar and brain stem injury. Complete tumor resection was accomplished in 99% of the patients, and there was no evidence of recurrence in this group. Only 1 of the 179 patients underwent incomplete tumor resection; he required subsequent surgery for symptomatic tumor regrowth. Our patient follow-up had a mean duration of 70 months and a median of 65 months (range, 3-171 mo). CONCLUSION: Our results are similar to those of other large microsurgical series of acoustic neuromas. Unless a patient has major medical problems, microsurgery by an experienced team of surgeons is preferred over radiosurgery.

Management and long-term outcome of adenoid cystic carcinoma with intracranial extension: a neurosurgical perspective.

Adenoid cystic carcinoma is a tumor of minor and major salivary glands that often invades the cranial base and intracranial cavity via local and perineural spread. In the past, the role of neurosurgeons in managing these tumors has been limited. The growth of interdisciplinary cranial base surgical approaches has now increased the involvement of neurosurgeons in the management of these tumors. We present a series of 16 patients with adenoid cystic carcinomas with cranial base and intracranial extension, the largest series reported in the neurosurgical literature. We have focused our approach on a neurosurgical perspective and made recommendations for the treatment of these tumors in relation to the following specific aspects of this disease. 1) The management of the carotid artery: In our experience, when the carotid artery is involved by tumor, a preliminary cerebral revascularization procedure with a cervical carotid to middle cerebral artery vein bypass graft should be performed before tumor resection. 2) The management of the cavernous sinus and orbit: Cavernous sinus tumor should be removed as fully as possible, but every effort should be made to preserve the IIIrd and IVth cranial nerves to achieve optimal functional and cosmetic results. The orbit should be exenterated when there is intraconal involvement; otherwise, intraorbital tumor can be removed with orbital preservation. 3) The use of palliative surgery: We have found that the use of palliative surgery can be considered even in patients whose extent of local disease precludes a surgical cure. The slow progression of the disease allows for long-term survival of many patients with advanced local disease and even of those with metastatic disease. 4) The long-term survival of these patients: In our series, six patients had no evidence of local disease and a mean survival of 72 months, one living patient had evidence of local disease and has survived 56 months, eight patients died of disease, with a mean survival of 137 months, and one patient died of complications after surviving for 63 months.

Primary craniofacial chordoma: case report.

A 37-year-old man presented with right facial pain and a nonpalpable mass over the malar eminence. An incisional biopsy via the intraoral route was performed and interpreted as a vascular malformation with degenerative changes. His symptoms persisted, and a repeat biopsy was suggestive of an epithelioid nerve sheath tumor. Total resection of the tumor was planned to include the infraorbital and malar regions, the infratemporal fossa, and the pterygopalatine fossa. At surgery, the tumor was removed with tumor-free margins obtained along the course of the maxillary nerve just before its entrance into the cavernous sinus. The pathological findings and the immunohistochemistry demonstrated a typical chordoma with no chondroid or sarcomatous dedifferentiation. We think that with greater use of immunohistochemical markers and electron microscopy, patients with chordoma in this location may be diagnosed promptly and accurately.

Craniocerebral epidermoid and dermoid tumours: a review of 32 cases.

We reviewed 22 epidermoid and 10 dermoid tumours of the skull and brain from patients operated on consecutively at Henry Ford Hospital between 1975 and 1991. There were 19 intradural (16 epidermoid, 3 dermoid) and 13 extradural (6 epidermoid, 7 dermoid) lesions. The average age at presentation was 35 years for patients with epidermoids and 15 years for those with dermoids. Common clinical presentations for patients with intradural lesions included headache, visual deficits, and seizures, whereas patients with extradural lesions harbored asymptomatic scalp masses. All patients with intradural lesions were investigated with computed tomography (CT) and cerebral angiography, and 8 patients underwent magnetic resonance imaging (MRI). Total resection was possible in 12 (92%) of 13 extradural tumours, all with excellent outcomes. Eight (42%) of the intradural tumours were completely resected. Overall, with the intradural tumours we had good to excellent results in 17 patients (90%), poor results in 1 (5%), and 1 death (5%). Re-operation was needed in 5 intradural recurrences (26%) with deterioration in only one patient's neurologic status postoperatively. From a review of ours and others' data, we conclude that 1) these tumours have an insidious onset despite significant size and mass effect as demonstrated by imaging studies; 2) CT, angiography, and particularly MRI help to define the extent of subarachnoid tumour spread and involvement of neurovascular structures, thus permitting better surgical planning; 3) a significant number of intradural tumours are difficult to excise because of their adherence to neurovascular structures, and thus are related to higher morbidity and mortality; and 4) because of extremely slow growth, complete tumour resection should not be the goal at the risk of injury to neurovascular structures.