Spinal Compliance as a Candidate Physiologic Marker of Response to Empiric Epidural Blood Patching in Patients with...

Patients with clinically suspected spontaneous intracranial hypotension (SIH) but non-localizing myelography frequently undergo empiric epidural blood patching, yet objective physiologic markers to help guide treatment remain limited. Spinal compliance, measured during myelographic pressure-volume augmentation, reflects dynamic pressure-volume behavior of the thecal sac and may capture clinically relevant physiology not evident on static imaging or opening pressure alone. We evaluated whether spinal compliance is associated with clinical response to empiric epidural blood patching in this diagnostically challenging subgroup.

We performed a retrospective analysis of prospectively collected data from a single-center CSF leak program. Patients were included if they had calculable spinal compliance from a non-localizing myelogram, underwent empiric epidural blood patching, and had documented clinical follow-up. Patients with confirmed CSF leaks were excluded. Treatment response was dichotomized as any sustained clinical benefit versus no sustained benefit. Logistic regression was used to assess associations with response, including a clinically informed model incorporating sex as a covariate based on prior literature.

Forty-four patients met inclusion criteria. Fourteen (32%) reported sustained clinical benefit from empiric blood patching and 30 (68%) did not. Responders demonstrated higher spinal compliance than non-responders (1.48 ± 1.23 vs 1.00 ± 0.44 mL/cmH₂O; Cohen's d = 0.52), with a stepwise increase in response rate across compliance tertiles (19%, 38%, 42%). Although compliance alone did not reach significance on univariable analysis (Mann-Whitney p = 0.17; likelihood ratio p = 0.06), a multivariable model incorporating compliance and sex was associated with treatment response (AUC = 0.71, 95% CI 0.56 to 0.86; likelihood ratio p = 0.02). Opening pressure also showed complementary signal (AUC = 0.67, 95% CI 0.52 to 0.82; likelihood ratio p = 0.06).

In patients with suspected spinal CSF leak and non-localizing myelography, higher spinal compliance was associated with greater likelihood of sustained benefit after empiric epidural blood patching. The strongest signal emerged when compliance was interpreted within a clinically informed multivariable framework, with opening pressure contributing additional complementary information. These findings support spinal compliance as a promising candidate physiologic marker for prospective study in a subgroup where objective treatment guidance remains limited.