Factors that influence neurological deficit and recovery in lumbar disc prolapse—a narrative review

Neurodeficit due to lumbar disc herniation (LDH) is a serious complication and can range from sensory hypoesthesia in a single dermatome to a debilitating condition like cauda equina syndrome (CES). Many authors have described variable clinical and radiological risk factors for neurodeficit in LDH. Similarly the prognostic factors influencing recovery have been variable across the studies. This narrative review discusses the pathogenesis, most consistent factors associated with the occurrence of neurodeficit in LDH patients and also the factors which have a prognostic role in recovery. Pathological mechanisms like venous congestion, neuronal ischaemia and multiple root impairment act either individually or in combination to result in neurodeficit in LDH patients. Among the clinical risk factors, diabetes mellitus and acute onset of symptoms have been associated with neurodeficit while pre-existing spinal canal stenosis, non-contained discs (sequestrated/migrated) are potential radiological risk factors for developing neurodeficit. When considering prognostic factors for recovery, pre-operative muscle strength is the only significant factor. Knowledge about the causative and prognostic factors in neurodeficit following LDH would help in the successful management of this condition.