Cerebrospinal Fluid Refill Test

Cerebrospinal fluid (CSF) hypovolemia is often difficult to diagnose because reduced CSF pressure and radiographic findings are not consistently observed. To address this limitation, we developed the CSF refill test, a novel diagnostic procedure based on temporary CSF replenishment and evaluation of symptom improvement. This study reports preliminary and prospective results of this method.

We analyzed 27 patients with suspected CSF hypovolemia. Seventeen cases (2012-2019) were retrospectively assessed during procedures such as computed tomography myelography and the overflow leak test, in which 10-20 mL of artificial CSF or saline was administered intrathecally. Ten additional patients (2019-2021) were prospectively enrolled and underwent a standardized CSF refill test, which involved intrathecal injection of 10 mL of ARTCEREB. Symptom changes, including orthostatic headache, were evaluated immediately after the procedure.

Clear improvement of orthostatic headache was observed in 25 of 27 patients (93%), with 19 experiencing complete resolution. Transient improvements were also noted in associated symptoms, such as visual dimness, tinnitus, and dizziness. The duration of improvement ranged from several hours to up to 3 weeks. No serious adverse events occurred; only mild transient side effects such as head discomfort or puncture site pain were reported.

The CSF refill test is a promising diagnostic tool for CSF hypovolemia that directly demonstrates symptom improvement after CSF replenishment. It may aid in diagnosis, guide treatment decisions, and predict therapeutic response to epidural blood patch therapy.