Ten-year spontaneous intracranial hypotension with acquired tonsillar descent and syringomyelia from a T3-4 ventral dural defect: importance of digital subtraction myelography localization and role of direct repair. Illustrative case.

backgroundSpontaneous intracranial hypotension (SIH) is an underrecognized yet increasingly diagnosed cause of orthostatic headaches. Reduction of intracranial CSF volume and pressure produces characteristic imaging findings such as diffuse pachymeningeal enhancement and cerebellar tonsillar descent, mimicking a Chiari malformation type I. Distinguishing SIH from other causes of hindbrain herniation is critical for prompt recognition and targeted treatment to resolve symptoms and radiological abnormalities. OBSERVATIONS: A 55-year-old male patient presented with a history of persisting postural headaches, back pain, and sensory loss. MRI of the spine demonstrated a subtle ventral epidural fluid collection extending along the cervical and thoracic spine. Intraoperative digital subtraction myelography confirmed a CSF leak site at the T3-4 level due to a dural defect. Under the same anesthetic, a posterior T3-4 laminectomy and intradural repair of the ventral dural defect were performed. The patient recovered with complete resolution of symptoms and no neurological deficits or weakness. Postoperative MRI showed resolution. LESSONS: Identifying a pathological defect can be challenging in SIH, especially in chronic cases that mimic Chiari malformation type I due to tonsillar decent. The authors illustrate the clinical, radiological, and surgical framework utilized at their institution for managing a chronic SIH case due to a ventral dural defect. https://thejns.org/doi/10.3171/CASE26369.