Multimodality Neuromonitoring in XLIF

Inclusion Criteria: * Persistent back and/or leg pain unresponsive to conservative treatment for at least six (6) months, unless surgical treatment is clinically indicated earlier * Indicated for extreme lateral interbody fusion at any number of levels inclusive of L4-5 * At least 18 years of age at the date of written informed consent * Able to undergo surgery based on physical exam, medical history and surgeon judgment * Willing and able to return for post-treatment exams according to the follow-up called for in the protocol * Signed and dated informed consent form Exclusion Criteria: * Patient has a mental or physical condition that would limit the ability to comply with study requirements * Patient is a prisoner * Patient is involved in active litigation relating to the spine (worker's compensation claim is allowed if it is not contested) * Patient has an underlying neurological disease or neurological deficit that is not associated with the condition for which he/she is seeking surgical intervention (e.g., diabetic peripheral neuropathy) * Patient is participating in another clinical study that would confound study data