Femoral nerve neuromonitoring for lateral lumbar interbody fusion surgery.

BACKGROUND CONTEXT: The transpsoas lateral lumbar interbody fusion (LLIF) technique is an effective alternative to traditional anterior and posterior approaches to the lumbar spine; however, nerve injuries are the most reported postoperative complication. Commonly used strategies to avoid nerve injury (eg, limiting retraction duration) have not been effective in detecting or preventing femoral nerve injuries. PURPOSE: To evaluate the efficacy of emerging intraoperative femoral nerve monitoring techniques and the importance of employing prompt surgical countermeasures when degraded femoral nerve function is detected. STUDY DESIGN/SETTING: We present the results from a retrospective analysis of a multi-center study conducted over the course of 3 years. PATIENT SAMPLE: One hundred and seventy-two lateral lumbar interbody fusion procedures were reviewed. OUTCOME MEASURES: Intraoperative femoral nerve monitoring data was correlated to immediate postoperative neurologic examinations. METHODS: Femoral nerve evoked potentials (FNEP) including saphenous nerve somatosensory evoked potentials (snSSEP) and motor evoked potentials with quadriceps recordings were used to detect evidence of degraded femoral nerve function during the time of surgical retraction. RESULTS: In 89% (n=153) of the surgeries, there were no surgeon alerts as the FNEP response amplitudes remained relatively unchanged throughout the surgery (negative group). The positive group included 11% of the cases (n=19) where the surgeon was alerted to a deterioration of the FNEP amplitudes during surgical retraction. Prompt surgical countermeasures to an FNEP alert included loosening, adjusting, or removing surgical retraction, and/or requesting an increase in blood pressure from the anesthesiologist. All the cases where prompt surgical countermeasures were employed resulted in recovery of the degraded FNEP amplitudes and no postoperative femoral nerve injuries. In two cases, the surgeons were given verbal alerts of degraded FNEPs but did not employ prompt surgical countermeasures. In both cases, the degraded FNEP amplitudes did not recover by the time of surgical closure, and both patients exhibited postoperative signs of sensorimotor femoral nerve injury including anterior thigh numbness and weakened knee extension. CONCLUSIONS: Multimodal femoral nerve monitoring can provide surgeons with a timely alert to hyperacute femoral nerve conduction failure, enabling prompt surgical countermeasures to be employed that can mitigate or avoid femoral nerve injury. Our data also suggests that the common strategy of limiting retraction duration may not be effective in preventing iatrogenic femoral nerve injuries.

Upper cervical anterior diskectomy and fusion improves discogenic cervical headaches.

STUDY DESIGN: Retrospective patient identification and prospective data collection were performed. OBJECTIVE: To evaluate the outcome of anterior cervical diskectomy and fusion for discogenic cervical headaches. SUMMARY OF BACKGROUND DATA: Cervicogenic headaches affect up to 2.5% of the population. One cause is discogenic pain. Because anterior cervical diskectomy and fusion may improve neck pain, the effect of this procedure on discogenic cervical headaches was evaluated. METHODS: Nine patients with severe refractory cervicogenic headaches who underwent anterior cervical diskectomy and fusion of the upper cervical discs were retrospectively identified on the basis of clinical, radiographic, and diskography findings. Pain was measured by a numerical rating scale, and function by the Oswestry Disability Index. RESULTS: The study involved six women and three men with a mean age of 52 (range, 35-72 years) and a mean follow-up period of 37 months (range, 24-49 months). Anterior cervical diskectomy and fusion was performed at both C2-C3 and C3-C4 in seven patients, at C2-C3 in one patient, and at C2-C3, C3-C4, and C4-C5 in one patient. Associated symptoms included nausea, arm pain, dizziness, and visual disturbances. All the patients improved. All stated that they would have the same surgery again for the same outcome. The mean numerical rating score improved from 8 (range, 5-10) to 2.7 (range, 0-7) ( < 0.001), and five patients (56%) had total headache relief. The mean Oswestry Disability Index improved from 62 (range, 42-87) to 35 (range, 2-82) ( < 0.009). The associated symptoms resolved in all the patients. There was early moderate to severe dysphagia in three patients, and mild dysphagia in four patients. At the final follow-up assessment, five patients evidenced mild dysphagia. CONCLUSIONS: Anterior cervical diskectomy and fusion appears to be quite effective for discogenic cervical headache, but should be reserved for patients who are extremely impaired and refractory to all other treatments.