Mild-Type Infantile Acute Subdural Hematoma Followed by Subdural Hematohygroma: Report of A Case Suggesting Common Etiology Causing Acute Subdural Hematoma and Hematohygroma
Background: Infantile acute subdural hematoma (IASDH) and subdural hematohygroma (SDHy) have
been seemingly closely related disorders, to date, however, there have been poorly elucidated concerning
the etiological relationship. The present case report aimed to approach possible etiology commonly
developing both disorders.
Case description: A one month-old girl suffered fever associated with poor milk feeding. Because these
symptoms failed to subside and the diagnosis was undefinitive, she was transiently hospitalized for
sepsis workup. Head CT revealed focal enlargement of subarachnoid space (SAS), and MRI 9 days later
showed benign enlargement of subarachnoid space.
Two months later, however, she was noted to have generalized convulsive seizure, prompting to refer to
a nearby hospital. At the emergency room, although she was alert and asymptomatic, head CT revealed
acute subdural hematoma (ASDH). Ophthalmological examination failed to reveal retinal hemorrhage.
MRI 9 days later disclosed disappearance of ASDH and newly developed bilateral SDHy. Her clinical
course was uneventful, and follow-up CT at the age of 4 months showed enlargement of subarachnoid
spaces on both frontotemporal regions and disappearance of SDHy.
Discussion and conclusion: In the present case, clinical course and serial neuroimaging findings,
particularly CT and MRI at the age of one month undergone as routine sepsis workup without
neurological events, are invaluable to elucidate the pathological similarity between IASDH and SDHy.
Second CT taken after seizure showed thin film-like ASDH associated with enlargement of SAS, typical
features seen in mild-type IASDH. On the other hand, second MRI 9 days after CT revealed disappearance
of ASDH, and disclosed bilateral SDHy associated with benign enlargement of subarachnoid space. This
phenomenon indicates early disappearance of mild-type IASDH together with progressive enlargement
of SAS probably leading to development of SDHy.
