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Laligam N. Sekhar and Aage R. Møller

✓ In the past, neurosurgeons have been reluctant to operate on tumors involving the cavernous sinus because of the possibility of bleeding from the venous plexus or injury to the internal carotid artery (ICA) or the third, fourth, or sixth cranial nerves. The authors describe techniques for a more aggressive surgical approach to neoplasms in this area that are either benign or locally confined malignant lesions.

During the last 2 years, seven tumors involving the cavernous sinus have been resected: six totally and one subtotally. The preoperative evaluation included axial and coronal computerized tomography, cerebral angiography, and a balloon-occlusion test of the ICA. Intraoperative monitoring of the third, fourth, sixth, and seventh cranial nerves was used to assist in locating the nerves and in avoiding injury to them. The first major step in the operative procedure was to obtain proximal control of the ICA at the petrous apex and distal control in the supraclinoid segment. The cavernous sinus was then opened by a lateral, superior, or inferior approach for tumor resection. Temporary clipping and suture of the ICA was necessary in one patient.

None of the patients died or suffered a stroke postoperatively. Permanent trigeminal nerve injury occurred in three patients; in two, this was the result of tumor invasion. One patient suffered temporary paralysis of the third, fourth, and sixth cranial nerves, and in another the sixth cranial nerve was temporarily paralyzed. Preoperative cranial nerve deficits were improved postoperatively in three patients. Radiation therapy was administered postoperatively to four patients. These seven patients have been followed for 6 to 18 months to date and none has shown evidence of recurrence of the intracavernous tumor.

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Cerebellopontine angle meningiomas

Microsurgical excision and follow-up results

Laligam N. Sekhar and Peter J. Jannetta

✓ During the years 1974 through 1981, 22 patients with cerebellopontine angle meningiomas underwent surgery: 14 tumors were excised completely, and eight subtotally. A retromastoid approach was used in 19 cases and a subtemporal approach in three cases. There was no operative mortality and the quality of survival was good. Five patients suffered new cranial nerve deficits as a result of the operation. The average follow-up period was 5 years. One tumor thought to be completely removed has recurred, but has not required another operation so far. One subtotally excised tumor required reoperation. Computerized tomography and arteriography were important in preoperative evaluation. Good neuroanesthesia, the use of the surgical microscope and microtechnique, and an understanding of the pathological relationships were factors contributing to good results.

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Anomalous subarcuate loop

Technical note

Atul Goel and Laligam N. Sekhar

✓ An anomalous subarcuate loop of the anterior inferior cerebellar artery is described in which the artery is adherent to or penetrates the posterior fossa dura in the subarcuate fossa. When encountered during acoustic neurilemoma surgery, the artery should be carefully mobilized along with a sleeve of dura to prevent its injury.

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Akio Morita and Laligam N. Sekhar

✓ Protection of the vein of Labbé is a significant concern during surgery that involves retraction of the temporal lobe. A cranial base surgical approach, especially one via the presigmoid—petrosal route, carries considerable risk to this venous complex. A case is presented in which a large dominant vein of Labbé was injured during resection of a petroclival meningioma. This vein drained all the sylvian venous circulation as well as the lateral temporal surface; no connection to another venous system was noted. The vein was successfully reconstructed using a short saphenous vein bypass graft. Significant complications could have occurred without this reconstruction. The technique and benefits of this type of reconstruction are discussed.

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Chandra Nath Sen and Laligam N. Sekhar

✓ The subtemporal and preauricular infratemporal operative technique is an approach to the skull base through the anterior portion of the petrous temporal bone and is used for the removal of predominantly extradural tumors in this region. The present study, based on dissection of human cadavers, describes the use of this approach for the management of intradural lesions in the region of the clivus. Its main advantages include avoidance of brain retraction, the use of an extrapharyngeal route, and exposure of the ventral aspect of the pons and medulla and related structures caudal to the trigeminal root. This approach can easily be combined with an intradural subtemporal approach to provide additional exposure of the superior clivus rostral to the trigeminal root. Combining the two approaches provides direct access to the ventral surface of the entire brain stem from the dorsum sellae to the hypoglossal foramina. Five patients with lesions in the clivus and petrous apex have been operated on via this approach. Details of the anatomical aspects of the approach and its applications are presented.

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Laligam N. Sekhar and Jack F. Wasserman

✓ Using an electronic stethoscope, the authors have attempted noninvasive detection of intracranial aneurysms, arteriovenous malformations (AVM's), and carotid cavernous fistulas in 45 patients. A microphone of older design and a newly designed horn-coupled probe microphone were used to record the sound signals emanating from the cranium. A trigger pulse recorded by another microphone placed over the carotid area or the precordium was used to time the intracranial signals. The sound signals were converted to electrical signals, amplified, filtered, and analyzed using fast Fourier transformation to give plots of amplitude versus frequency of the signals. A spike at a certain frequency or a bruit over a band of frequencies was considered a positive finding. The records of 18 of the patients were not satisfactory for analysis, mainly due to external noise interference. Eight of 11 aneurysm patients with satisfactory recordings emitted resonant spikes, turbulent bruits, or combinations of the two. The other three records were negative. Four patients with AVM's and two with carotid cavernous fistulas exhibited broad-band bruits representing turbulent flow. Neither spikes nor bruits were demonstrable in three patients with brain tumors or in seven patients without intracranial vascular lesions. Experimental vein pouch aneurysms were also induced in two dogs. Recordings from these animals revealed resonant spikes. The limitations and scope of electronic stethoscope audiometry are discussed.

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Ghassan K. Bejjani and Laligam N. Sekhar

✓ Neurovascular compression syndromes are usually treated by interposing Teflon felt or padding or some other implant between the offending vessel and the nerves. However, this cannot be done in some cases in which ectatic vertebrobasilar arteries are involved. In these instances, alternative techniques must be used.

The authors report the use of a sling made of Prolene to reposition the vertebral artery in two patients with neurovascular compression disorder. The clinical results were gratifying, with complete resolution of the patients' symptoms.

Compression by large vessels is an uncommon but important source of neurovascular compression in patients with trigeminal neuralgia, hemifacial spasm, disabling positional vertigo, and, possibly, hypertension. The technique described may be useful to surgeons treating these problems.

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Roberto C. Heros and Laligam N. Sekhar

✓ An increasing number of patients with symptomatic carotid artery occlusion are being referred for extracranial to intracranial bypass grafts. After careful clinical and angiographic assessment, a number of these patients have been treated with a direct approach to the carotid arteries in the neck or with anticoagulation rather than with a bypass graft. These patients may be categorized diagnostically under the following headings: 1) complete occlusion of the internal carotid artery (ICA) with intracranial patency; 2) spontaneous dissection of the ICA; 3) atheromatous pseudo-occlusion; 4) carotid artery occlusion with stenosis of the contralateral ICA; 5) occlusion of the ICA and stenosis of the external carotid artery; and 6) thrombus in the intracranial segment of an occluded ICA. Each of these categories is discussed briefly, and illustrative cases are presented.

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Laligam N. Sekhar, Chandra N. Sen and Hae Dong Jho

✓ Saphenous vein graft reconstruction was performed from the petrous to the supraclinoid internal carotid artery (ICA) to replace the cavernous ICA in six patients during direct intracavernous operations. Four of these patients had intracavernous neoplasms with invasion of the ICA and two had intracavernous ICA aneurysms that could not be clipped or occluded with intraluminal balloons. All but one patient had evidence of poor collateral flow reserve in a balloon occlusion test of the ICA. The superficial temporal artery was not present in four patients, was minuscule in one, and was damaged during the initial dissection in another, making it unsuitable for superficial temporal-to-middle cerebral artery branch anastomosis.

Blood flow within the graft could not be established intraoperatively in one patient (who had excellent collateral circulation) due to the small size of the vein (3 mm). In all others, the grafts were patent on follow-up arteriography and transcranial Doppler studies. Three patients who had severe reduction of cerebral blood flow during test occlusion of the ICA exhibited temporary hemispheric neurological deficits postoperatively; the deficits were related to the duration of temporary ICA occlusion. All three recovered completely without evidence of infarction on computerized tomography (CT). One patient who clinically could not tolerate the balloon occlusion test of the ICA also had temporary neurological deficits with good recovery but showed evidence of border-zone infarction on CT scans. The present role of saphenous vein graft bypass of the cavernous ICA is discussed.