Back pain with lower extremity symptoms can be concerning for cauda equina. Some pointers regarding the H&P:
Symptoms develop within less than 24 hours in 90% of patients
Urinary retention develops before incontinence, but up to 30% of patients will have neither.
Saddle anesthesia or hypoesthesia is present in 81% of patients. Perineal numbness may be patchy, mild, and unilateral initially, making it difficult to elicit.
None of these symptoms independently predicts cauda equina syndrome with an accuracy greater than 65%.
Bottom Line: do not depend on any one finding to reliably exclude or confirm cauda equina.
References
Shapiro S. Medical realities of cauda equina syndrome secondary to lumbar disc herniation. Spine (Phila Pa 1976). 2000;25(3):348-351; discussion 352
Gardner A, Gardner E, Morley T. Cauda equina syndrome: a review of the current clinical and medico-legal position. Eur Spine J. 2011;20(5):690-697. (Review article)
Bell DA, Collie D, Statham PF. Cauda equina syndrome: what is the correlation between clinical assessment and MRI scanning? Br J Neurosurg. 2007;21(2):201-203
