Microvascular decompression for trigeminal neuralgia caused by vertebrobasilar compression

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✓ Thirty-one (2%) of 1404 consecutive patients with typical trigeminal neuralgia who underwent microvascular decompression between 1972 and 1993 were found to have vascular compression by the vertebral artery (VA) or the basilar artery (BA). Compared to the remaining 1373 patients, this subgroup was older (mean age 62 vs. 55 years, p < 0.001), was predominantly male (68% vs. 39%, p < 0.002), demonstrated left-sided predominance (65% vs. 39%, p < 0.002), was more likely to be hypertensive (65% vs. 18%, p < 0.001), and was more likely to have ipsilateral hemifacial spasm (16% vs. 0.6%, p < 0.001). The trigeminal nerve was compressed by the VA in 18 cases (the VA alone in three and the VA plus other vessels in 15), the BA in 12 cases (the BA alone in four and the BA plus other vessels in eight), and the vertebrobasilar junction in one case. Twenty-nine of the 31 patients underwent vascular decompression of the trigeminal nerve, one had a complete trigeminal root section, and one underwent partial root section with vascular decompression of the remaining nerve.

All 31 patients were pain-free, off medication immediately after surgery, and this pain-free, medication-free status was maintained at 1 year after surgery in 96% of cases, at 3 years in 92%, and at 10 years in 86%, based on life-table analysis. Minor trigeminal hypesthesia/hypalgesia was present preoperatively in 52%. New or worsened minor hypesthesia/hypalgesia developed in 41% of patients, while transient diplopia as well as hearing loss developed in 23% and 13% in the overall series, respectively. No patient developed major trigeminal sensory loss or masseter weakness after vascular decompression alone. There was no operative mortality. Vascular decompression is an effective treatment for patients with trigeminal neuralgia who have vertebrobasilar compression of the trigeminal nerve. Patients should be warned that decompression of a tortuous vertebrobasilar system carries a higher risk of mild trigeminal dysfunction, diplopia, and hearing loss than standard microvascular decompression.

Article Information

Address reprint requests to: Peter J. Jannetta, M.D., Department of Neurological Surgery, Room F948, Presbyterian University Hospital, 230 Lothrop Street, Pittsburgh, Pennsylvania 15213.

© AANS, except where prohibited by US copyright law.

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    Upper: Contrast-enhanced computerized tomography scans, axial view, in a 70-year-old man with left-sided trigeminal neuralgia caused by vertebral artery (VA) compression of the trigeminal nerve from below. The lower of the two images (left) demonstrates the left VA (black arrow), the right VA (open arrow), and the basilar artery (BA) (arrowhead) coursing from left to right ventral to the pons. The higher image (right) demonstrates the distal BA (arrowhead) and the distal left BA (arrow) just before it joins the proximal BA. Lower: Magnetic resonance T2-weighted images (TR 3000 msec, TE 80 msec), axial view, in a 63-year-old woman with left-sided trigeminal neuralgia caused by VA and anterior inferior cerebellar artery compression from below, elevating the trigeminal nerve root into the superior cerebellar artery above. The lower of the two images (left) demonstrates the left VA (white arrow) and the right VA (open arrow), both displaced to the left side of the lower pons. The upper image (right) demonstrates the left VA joining the proximal BA (arrowhead) as it passes from left to right ventral to the pons.

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    Intraoperative photographs taken through the operating microscope during a right retromastoid approach in a 63-year-old woman with left-sided trigeminal neuralgia. The patient was placed in the lateral decubitus position. Upper Left: The trigeminal nerve (V) is seen elevated rostrally into a large rostral vein (vein) by the basilar artery (BA) and the anterior inferior cerebellar artery (AICA). The tentorium (T) and the eighth cranial nerve (VIII) are also visualized. Upper Right: The BA and AICA have been mobilized from the trigeminal nerve and held away with Teflon felt (TF). The indentation caused by their previous compression is evident (arrow). The nerve has been moved somewhat away from the rostral vein, but distal contact is still present. Lower: Teflon felt has been interposed between the vein and the rostral surface of the trigeminal nerve, completing the decompression procedure.

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    A stem-and-leaf plot depicting the combination of trigeminal divisions affected in any given patient (on the left), as well as the total number of trigeminal divisions affected with trigeminal neuralgia (on the right), in 31 patients with vertebrobasilar compression. N = number of trigeminal divisions.

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    Kaplan-Meier life-table plot of the pain-free, medication-free rates for all 31 patients undergoing vertebrobasilar decompression. The pain-free, medication-free rates were 96%, 92%, and 86% at 1, 3, and 10 years after surgery, respectively.

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    Left vertebral digital subtraction angiogram, anteroposterior (left) and lateral (right) views, in a 54-year-old man with left-sided trigeminal neuralgia. This study was obtained 5 days after a left retromastoid craniectomy for microvascular decompression of the trigeminal nerve. The distal left vertebral artery is markedly elevated in the region of the trigeminal nerve origin (arrow).

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