Endoscopic Foraminal Decompression Preceding Oblique Lateral Lumbar Interbody Fusion To Decrease The Incidence Of Post Operative Dysaesthesia

BACKGROUND: Lumbar interbody fusion has become a well established method to diminish axial back pain as well as radiculopathy in patients with degenerative disc disease, stenosis, and instability. The concept of indirect decompression of the neural foramen and spinal canal while performing fusion became popular in the mid 1990’s with description of ALIF techniques. Morphometric analysis confirmed the extent of decompression of posterior elements with interbody height restoration. In an attempt to diminish potential complications associated with anterior or posterior approaches to the spine for interbody fusion, and with the hope of accomplishing fusion in a less invasive manner, lateral lumbar interbody fusion has become quite popular. This transpsoas approach to the disc space has been associated with a high incidence of neurologic complications. Even though this is the first technique to routinely recommend EMG monitoring to increase safety in the approach, neurologic injuries still occur. A newer oblique lateral lumbar interbody (OLLIF) approach has recently been described to lessen the incidence of neurologic injury. This technique also advocates use of EMG testing to lessen neurologic trauma. In spite of this precaution, neurologic insult has not been eliminated. In fact, even in patients whose electrical stimulation thresholds suggested a safe entry space into the disc, transient dysaesthesia continues to occur in 20-25 percent of cases. PURPOSE: This pilot study reflects data and observations of a subset of patients treated with endoscopic foraminotomy preceding oblique lateral lumbar interbody fusion (OLLIF) to assess specifically potential improvements in dysaesthesia rates. METHODS: A select subset of patients undergoing OLLIF failed to meet electrodiagnostic criteria for safe disc access through Kambin’s triangle. These patients underwent an endoscopic foraminotomy and exiting nerve decompression prior to discectomy, endplate preparation and cage insertion. RESULTS: Dysaesthesia did not occur in these patients whom otherwise would have likely been at risk for neurologic deficit. CONCLUSIONS: These findings suggest that patients at risk for neurologic insult during oblique lateral lumbar interbody fusion can be protected by foraminoplasty.