Infantile Acute Subdural Hematoma. Clinical and Neuroimaging Analyses of 15 Cases Focusing on Intracranial Structural Vulnerabilities

Objectives: There are annually approximately 100 cases of Infantile Acute Subdural Hematoma (IASDH) in Japan. Even after the advent of magnetic resonance imaging, few studies have examined the clinical profile and neuroimaging characteristics of IASDH. The present study aimed to elucidate the intracranial, structural vulnerabilities associated with IASDH. Materials & Methods: Fifteen patients with IASDH comprising 14 males and one female aged less than 2 years were enrolled. Patients with a diagnosis of shaken baby syndrome or abusive head trauma were excluded. Results: The patients' head traumaresulted from a short fall (n=13; 87%) and occipital impact (n=11; 73%). A retinal hemorrhage was noted in 12 patients (80%). Imaging studies revealed a mixed-density, unilateral, subdural hematoma in all the patients. Benign Enlargement of the Subarachnoid Space (BESS) was noted in eight patients (53%), and a Large Sylvian Fissure (LSF) coexisting with Small Temporal Lobes (STL) was present in all the patients (100 %). Surgery was performed in four patients (craniotomy: n=3; subdural drainage: n=1) while 11 patients (73%) were conservatively managed. The outcomes were good in 13 patients (87%) while two patients had severe to moderate disability. Conclusion: IASDH consists of a mixed-density hematoma possibly caused by simultaneous tearing of the arachnoid membranes and bridging veins. The presence of LSF and BESS increases the Cranio-Cerebral Disproportion (CCD). Inparticular, the co-occurrence of LSF with STL may contribute to loosening the tight fixation of the temporal lobes at the middle cranial fossa and sphenoid ridge. In this situation, a mild occipital impact may sufficiently enhance the rotational force of the brain to induce IASDH.