To investigate the clinical and imaging characteristics of patients with herniation secondary to critical cerebrospinal fluid hypovolemia (CCSFH) after craniotomy.

From January 2019 to November 2023, fourteen patients with acute brain injury were admitted to Neurosurgery Department of Beijing Shunyi District Hospital, and experienced cerebral herniation due to CCSFH after craniotomy. Their clinical and imaging characteristics, treatment course, and outcomes were analyzed. Prognosis at six months post-discharge was assessed with the modified Rankin scale (mRS).

CCSFH occurred within 1 to 13 d post-surgery. Seven patients exhibited a decline in consciousness or mental state, with three showing anisocoria. The remaining seven patients had regular pupil sizes, complicating consciousness assessment due to postoperative sedation and analgesia. The midline shift was (10.95±2.90) mm during the CCSFH presentation, ranging from 6.69 to 16.00 mm. Intracranial pressure ranged from 1-11 mmHg (1 mmHg=0.133 kPa) in 5 cases with CCSFH. Four cases underwent decompressive craniectomies owing to delayed CCSFH identification, while 10 cases received conservative treatment. The CCSFH condition was successfully reversed in all patients. Six months post-discharge, 6 cases had mRS scores≤2, and 8 had scores>2.

Post-craniotomy CCSFH often presents with deteriorating consciousness or mental status, and in severe cases, it may lead to transtentorial herniation. CT scans show significant midline shift, but the intracranial pressure remains relatively low. The primary treatment is positioning the patient supine, along with stopping cerebrospinal fluid drainage, halting use of hypertonic diuretics, and administering intravenous hydration, which often leads to good outcomes.