Threshold Response of Lumbar Selective Nerve Root Block in Predicting Good Outcome Following Lumbar Foraminotomy

SNRB, as measured by the change in pain and objective functional ability, can solicit crucial information regarding a patient's clinical picture and can predict a patient's outcome post-surgery. By using the walk test as an objective functional assessment, the aim is to better standardize the threshold for a positive response to SNRB. In summary, SNRB, despite utilized frequently in the diagnostic work-up with patients with lumbar radiculopathy, vary widely in their sensitivity and specificity. The reasons, as outlined above, are multifactorial. The proposed study aims to minimize the known limitations of these injections and prospectively define their positive and negative predictive value in a homogenous group of patients undergoing surgery for lumbar foraminal stenosis and radiculopathy. The design will define a threshold of response utilizing both subjective and objective measures and more accurately predict excellent results following surgery.

The proposed study will identify the threshold response level that quantifies the predictive value of diagnostic SNRBs in patients who present with lumbar foraminal stenosis and radiculopathy. Specifically, the proposed study will address the question of whether there is a degree or length of response to SNRB, which predicts an excellent surgical outcome. The hypothesis is that diagnostic SNRBs, when performed correctly, are useful in localizing the level of involvement in LSS and improve the accuracy and efficacy of surgical intervention. Use of diagnostic SNRBs will thus be used to clarify the clinical picture, giving the surgeon the information to make the right decision to operate or not, and, in the case of operation, predicting the optimal level(s) for surgical intervention. In addition, the investigators plan to identify and fully characterize a standard threshold level and time of nerve block response that will optimize the accuracy, specificity, and sensitivity of SNRB in predicting surgical outcomes.