Unraveling the cause of microspurs in spontaneous intracranial hypotension type 1: discogenic origin or calcified Hofmann’s ligament?

J Neurosurg Spine 44:315–319, 2026

This clinical study investigates the origin of ventral spinal microspurs causing spontaneous intracranial hypotension (SIH) type 1, comparing discogenic lesions with fibrotic tissue consistent with Hofmann’s ligament. Retrospective histopathological reanalysis of 27 surgically resected microspurs showed both discogenic and fibrotic origins, with 13 discogenic, 9 fibrotic, and 5 unclassifiable cases, and no significant differences in spur length, location, or CT density.

The authors conclude that ventral CSF leaks can arise from calcified intervertebral discs as well as calcified or fibrotic Hofmann’s ligaments, expanding the pathophysiological understanding of SIH and highlighting limitations from retrospective design, small sample size, and histological classification challenges.

Etiology of Microspurs: Microspurs causing ventral CSF leaks in spontaneous intracranial hypotension (SIH) type 1 can originate from both calcified intervertebral discs (discogenic) and calcified fibrous tissue associated with Hofmann’s ligament, not exclusively from disc material.

Histopathological Classification: Microspurs were histopathologically classified as either discogenic (cartilage/fibrocartilaginous tissue, often with secondary calcification) or fibrotic (hypercellular fibrous tissue with or without calcification, suggestive of Hofmann’s ligament).

Distribution: Most microspurs were located in the thoracic spine, with about one-third found at the cervicothoracic or thoracolumbar junctions, and the rest in the midthoracic region.

Imaging Findings: There was no statistically significant difference in microspur length or CT density (Hounsfield units) between discogenic and fibrotic (Hofmann’s ligament) origins, limiting the ability of imaging to distinguish between them preoperatively.

Clinical Implications: Both discogenic and fibrotic origins should be considered in the diagnosis and surgical planning for SIH with ventral CSF leaks, as relying solely on the discogenic theory may overlook alternative etiologies.

Pathophysiological Mechanism: Calcified microspurs, whether from discs or Hofmann’s ligament, may cause dural tears due to mechanical stress at spinal junctions or in regions with a narrow spinal canal.

Limitations: The study’s retrospective design, small sample size, and challenges in histopathological classification (lack of specific markers, possible sampling errors) limit the generalizability and precision of findings