Subcutaneous cysts: another cause of "failed" spinal anesthesia?

Spinal anesthesia continues to be one of the major techniques in the arsenal of the modern anesthesiologist. Inadequate anesthesia may follow a spinal anesthetic for a variety of reasons. We report a case in which entry of a spinal needle into a subcutaneous cyst mimicked the free flow of cerebrospinal fluid seen with dural puncture. This was confirmed by microscopic examination of the fluid, which was consistent with the contents of a subcutaneous cyst. This represents an unusual cause for failure of spinal anesthesia. Such a possibility should be borne in mind, especially when "clear fluid" return occurs through a spinal needle placed at a relatively superficial depth.