Occult, Dura-Perforating Disc Spurs as a Treatable Cause in ‘Spontaneous’ Intracranial Hypotension

Aim: Spontaneous intracranial hypotension is a rare but increasingly diagnosed condition. The pathomechanism consists of cerebrospinal fluid (CSF) outflow from the intra- to the extrathecal space through a putative dural tear. The nature, etiology, and location of the dural tear/CSF leak itself is currently unknown and is thought to be spontaneous or idiopathic in most cases. We present a case series with a proven diagnosis of CSF leak in which a systematic and meticulous search revealed micro, dura-perforating disc spurs as the treatable cause of ‘spontaneous’ intracranial hypotension.

Methods: A consecutive series of patients with symptoms of intracranial hypotension were evaluated for a systematic diagnostic work-up. We performed a spine focused, stepwise escalating imaging set (thin slice MRI of the spinal axis, MRI with intrathecal gadolinium, dynamic myelography and post myelography CT). As a final step, if the CSF leak could be restricted to one or two levels, we performed spinal surgery, including hemilaminectomy and microsurgical exploration of the presumed site of the CSF-leak.

Results: We identified 6 patients with symptoms of intracranial hypotension and corresponding imaging signs of spinal dural perforation with CSF leakage. Three of the suspected leaks were located in the cervical spine, one in the thoracic spine, and two in the cervico-thoracic junction. Three patients were initially treated by single or multiple epidural blood patches. Due to persisting symptoms all patients were scheduled for surgery. In all cases except one, a ventral dural perforation was verified. In 5 cases a micro, calcified disc spur extruding out of the disc space was visualized under the operating microscope. This micro spur perforated the dura and arachnoid and was the cause of CSF leak in all 5 cases. In one case a broad osteophyte had ripped the dura. All 5 disc spurs and the one broad osteophyte were micro-surgically removed, the dura was sealed, and the CSF leak ceased immediately.

Conclusions: The etiology of the CSF leak in spontaneous intracranial hypotension remains obscure. Here we present 6 patients in which a systematic spinal work-up, including microsurgical exploration, revealed dura perforating disc spurs. The dura-perforating disc spurs were the definitive and readily treatable causes of “spontaneous” intracranial hypotension.