Sciatic neuropathy due to popliteal fossa nerve block.

INTRODUCTION: Sciatic neuropathy after popliteal nerve block (PNB) for regional anesthesia is considered uncommon but has been increasingly recognized in the literature. We identified a case of sciatic neuropathy that occurred after bunionectomy during which a PNB had been performed. METHODS: To understand the frequency of PNB-related sciatic neuropathy, we performed a retrospective review of sciatic neuropathies at our center over a 5-year period. RESULTS: Forty-five cases of sciatic neuropathy were reviewed. Similar to earlier reports, common etiologies of sciatic neuropathy, including compression, trauma, fractures, and hip arthroplasty, were noted in the majority of our cases (60%, n = 27). Unexpectedly, PNB was the third most common etiology (16%, n = 7). CONCLUSIONS: Our results suggest PNB is a relatively common etiology of sciatic neuropathy and is an important consideration in the differential diagnosis. These findings should urge electromyographers to assess history of PNB in sciatic neuropathies, particularly with onset after surgery. Muscle Nerve 56: 822-824, 2017.

Predictive variables for the successful treatment of trigeminal neuralgia with gamma knife radiosurgery.

BACKGROUND: Gamma Knife radiosurgery (GKRS) has been reported to be an effective modality to treat trigeminal neuralgia. OBJECTIVE: To determine predictive factors for the successful treatment of trigeminal neuralgia with GKRS. METHODS: Between 1999 and 2008, 777 GKRS procedures for patients with trigeminal neuralgia were performed at our institution. Evaluable follow-up data were obtained for 448 patients. Median follow-up time was 20.9 months (range, 3-86 months). The mean maximum prescribed dose was 88 Gy (range, 80-97 Gy). Dosimetric variables recorded included dorsal root entry zone dose, pons maximum dose, dose to the petrous dural ridge, and cisternal nerve length. RESULTS: By 3 months after GKRS, 86% of patients achieved Barrow Neurologic Institute I to III pain scores, with 43% of patients achieving a Barrow Neurologic Institute I pain score. Twenty-six percent of patients reported posttreatment facial numbness; 28% of patients reported a post-GKRS procedure for relapsed pain, and median time to next procedure was 4.4 years. Multivariate analysis revealed that the development of postsurgical numbness (odds ratio [OR], 2.76; P = .006) was the dominant factor predictive of efficacy. Longer cisternal nerve length (OR, 0.85; P = .005), prior radiofrequency ablation (OR, 0.35; P = .028), and diabetes mellitus (OR, 0.38; P = .013) predicted decreased efficacy. The mean dose delivered to the dorsal root entry zone dose in patients who developed facial numbness (57.6 Gy) was more than the mean dose (47.3 Gy) given to patients who did not develop numbness (P = .02). CONCLUSION: The development of post-GKRS facial numbness is a dominant factor that predicts for efficacy of GKRS. History of diabetes mellitus or previous radiofrequency ablation may portend worsened outcome.

Repeat gamma knife radiosurgery for trigeminal neuralgia.

PURPOSE: Repeat gamma knife stereotactic radiosurgery (GKRS) for recurrent or persistent trigeminal neuralgia induces an additional response but at the expense of an increased incidence of facial numbness. The present series summarized the results of a repeat treatment series at Wake Forest University Baptist Medical Center, including a multivariate analysis of the data to identify the prognostic factors for treatment success and toxicity. METHODS AND MATERIALS: Between January 1999 and December 2007, 37 patients underwent a second GKRS application because of treatment failure after a first GKRS treatment. The mean initial dose in the series was 87.3 Gy (range, 80-90). The mean retreatment dose was 84.4 Gy (range, 60-90). The dosimetric variables recorded included the dorsal root entry zone dose, pons surface dose, and dose to the distal nerve. RESULTS: Of the 37 patients, 81% achieved a >50% pain relief response to repeat GKRS, and 57% experienced some form of trigeminal dysfunction after repeat GKRS. Two patients (5%) experienced clinically significant toxicity: one with bothersome numbness and one with corneal dryness requiring tarsorraphy. A dorsal root entry zone dose at repeat treatment of >26.6 Gy predicted for treatment success (61% vs. 32%, p = .0716). A cumulative dorsal root entry zone dose of >84.3 Gy (72% vs. 44%, p = .091) and a cumulative pons surface dose of >108.5 Gy (78% vs. 44%, p = .018) predicted for post-GKRS numbness. The presence of any post-GKRS numbness predicted for a >50% decrease in pain intensity (100% vs. 60%, p = .0015). CONCLUSION: Repeat GKRS is a viable treatment option for recurrent trigeminal neuralgia, although the patient assumes a greater risk of nerve dysfunction to achieve maximal pain relief.