PubMed · 5316997
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P B Eckman, R A Kramer, P H Altrocchi. 1971. Hemifacial spasm.. https://doi.org/10.1001/archneur.1971.00490010091012
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The published rates of operatively confirmed neurovascular compression as the cause for trigeminal neuralgia range from 10% to nearly 100%. High-definition magnetic resonance angiography (MRA) was performed in 27 consecutive patients (in 6 cases with 3D reconstructions) to show neurovascular compression preoperatively. The MRA findings were compared with the relationship between the Vth nerve and the surrounding vessels at surgery. In 23 patients MRA showed present neurovascular compression in accordance with surgical findings (18/27 in complete accordance of type and side of vessel, site and direction of compression). One woman had no neurovascular compression either on MRA or intraoperatively. One MRA prediction of neurovascular compression was false, and two results were false negative. The sensitivity of MRA was therefore 88.5% but the specificity only 50%, if surgical findings are the reference. In one patient with right trigeminal neuralgia MRA revealed bilateral neurovascular compression of the Vth nerves. Therefore, the overall specificity of MRA might be below 50%. In one patient with multiple sclerosis, the decision to operate was markedly influenced by the clear finding of neurovascular compression on MRA. The patient has been free from trigeminal pain for 149 weeks after microvascular decompression. In 6 patients, 3D reconstructions of the MRA data were performed. The images helped in 3D visualisation of the operation, but did not yield new information about the nature of the vessels revealed, or the site, direction or side of the neurovascular compression.
A long-standing but unfounded criticism of the translabyrinthine approach is the misperception that this approach does not give adequate access to the cerebellopontine angle. Because of what is perceived as limited visualization and operating space within the cerebellopontine angle, some surgeons still believe that the translabyrinthine approach is inappropriate for large acoustic tumors. In this study, the surgical access to the cerebellopontine angle by virtue of the translabyrinthine approach is measured and analyzed. The parameters are compared with those measured for the retrosigmoid approach. This series objectively confirms that the translabyrinthine approach offers the neurotologic surgeon a shorter operative depth to the tumor, via a similar-sized craniotomy. This permits superior visualization by virtue of a wider angle of surgical access. Such access is achieved with the merit of minimal cerebellar retraction.
OBJECTIVE: To assess the efficacy and safety of a new atraumatic, self-retaining cranial nerve electrode for direct cochlear nerve monitoring during cerebellopontine angle surgery. STUDY DESIGN: Prospective clinical investigation. SETTING: The Skull Base Surgery Center at Kaiser Permanente, San Diego, a tertiary referral center for neurotologic and skull-base surgery within Southern California Permanente Medical Group. PATIENTS: Eighteen patients, with aidable preoperative hearing, underwent direct cochlear nerve monitoring with this new electrode during cerebellopontine angle surgery for a variety of diagnoses. METHODS: Intraoperative observations of cochlear nerve action potential amplitude and latency were recorded. Preoperative and 1-month postoperative audiograms were compared to assess the degree of hearing preservation. Postoperative facial nerve function was assessed using the House-Brackmann method. RESULTS: Good auditory function was preserved in four of eight acoustic tumors, with poor hearing preserved in two additional patients. Good auditory function was preserved in the remaining ten patients. Cochlear nerve action potential amplitudes between 5 and 70 microV were recorded. Postoperative facial nerve function was House-Brackmann class I-II in all 18 patients. CONCLUSION: The authors find this new electrode to be safe and effective for monitoring cochlear nerve function during cerebellopontine angle surgery.