Headaches in chronic subdural hematoma: Does size matter?

Chronic subdural hematoma (cSDH) frequently presents with headache, but the relationship between hematoma size and headache is not well defined. This study aims to determine the relationship between total hematoma size and headache presentation in cSDH patients while identifying a critical size threshold for headache development.

We retrospectively reviewed adult cSDH patients diagnosed at our institution from January 1st, 2023, to June 4th, 2025. Patients with a Glasgow Coma Score (GCS) below 14 or a history of ventricular shunt were excluded. Data collected included demographic information, hematoma laterality, maximum cSDH diameter, headache on presentation, and GCS. Hematoma thickness was defined as the sum of maximum cSDH diameter on both sides. Multivariable logistic regression and receiver operating characteristic (ROC) analysis were performed to assess the association between headache presentation and hematoma thickness.

Among 341 eligible patients, 169 (49.6 %) presented with headache. Patients with headache had greater hematoma thickness (18.3 ± 10.7 mm vs. 15.1 ± 9.8 mm, p = 0.004) and more frequent midline shift (49 % vs. 32 %, p = 0.002). Multivariable analysis showed younger age (OR = 0.97; 95 %CI 0.95-0.99; p = 0.001) and larger hematoma thickness (OR = 1.03; 95 %CI 1.01-1.05; p = 0.029) were independently associated with headache. ROC analysis identified a hematoma thickness threshold of 12.5 mm (AUC = 0.596; 95 %CI 0.536-0.656, p = 0.002).

Younger age and larger hematoma thickness were independently associated with headache in patients with cSDH, which is multifactorial. A critical hematoma size threshold of 12.5 mm was derived for headache development, beyond which stretching of pain-sensitive structures may become clinically apparent.