Peter J. Jannetta
Peter J. Jannetta
Peter E. Sheptak and Peter J. Jannetta
✓ Total removal of huge acoustic neurinomas was carried out in 23 patients by means of a two-stage suboccipital transmeatal approach with microsurgical technique. There was no operative mortality. Good results were obtained in 18 (78%) of the patients who have returned to normal activities or full-time employment. Five patients (22%) have residual preoperative neurological deficits causing a reduced level of activity. All of these, except one, are able to care for themselves. None of the patients has had any further significant neurological deficit caused by the operative procedures. Anatomical integrity of the facial nerve was maintained in 17 patients (74%). Surgical technique, operative morbidity, and results are thoroughly discussed. The potential advantages of this technique are stressed.
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.
Ranjit K. Laha and Peter J. Jannetta
✓ Various factors have been considered in the etiology and pathogenesis of glossopharyngeal neuralgia. Vascular compression of the involved cranial nerves has been demonstrated in sporadic cases. In this series of six patients, it was noted with the aid of the operating microscope that the ninth and tenth cranial nerves were compressed by a tortuous vertebral artery or posterior inferior cerebellar artery at the nerve root entry zone in five cases. In selected patients, microvascular decompression without section of the nerves may result in a cure.
Aage R. Møller and Peter J. Jannetta
✓ Facial electromyographic (EMG) responses were monitored intraoperatively in 67 patients with hemifacial spasm who were operated on consecutively by microvascular decompression of the facial nerve near its exit from the brain stem. At the beginning of the operation, electrical stimulation of the temporal or the zygomatic branch of the facial nerve gave rise to a burst of EMG activity (autoexcitation) and spontaneous EMG activity (spasm) that could be recorded from the mentalis muscle in all patients. In some patients, the spontaneous activity and the autoexcitation disappeared after the dura was incised or when the arachnoid was opened, but stimulation of the temporal branch of the facial nerve caused electrically recordable activity in the mentalis muscle (lateral spread) with a latency of about 10 msec that lasted until the facial nerve was decompressed in all but one patient, in whom it disappeared when the arachnoidal membrane was opened.
When the facial nerve was decompressed, this lateral spread of antidromic activity disappeared totally in 44 cases, in 16 it was much reduced, and in seven it was present at the end of the operation at about the same strength as before craniectomy. In four of these last seven patients there was still very little improvement of the spasm 2 to 6 months after the operation; these four patients underwent reoperation. In two of the remaining three patients, the spasm was absent at the 3- and 7-month follow-up examination, respectively, and one had mild spasm. Of the 16 patients in whom the lateral spread response was decreased as a result of the decompression but was still present at the end of the operation, 14 had no spasm and two underwent reoperation and had mild spasm at the last examination. Of the 44 patients in whom the lateral spread response disappeared totally, 42 were free from spasm and two had occasional mild spasm at 6 and 13 months, respectively, after the operation.
Monitoring of facial EMG responses is now used routinely by the authors during operations to relieve hemifacial spasm, and is performed simultaneously with monitoring of auditory function for the purpose of preserving hearing. The usefulness of monitoring both brain-stem auditory evoked potentials recorded from electrodes placed on the scalp and compound action potentials recorded directly from the eighth cranial nerve is evaluated.