[Slowly progressive expanding hematoma in the Basal Ganglia: a report of 3 cases and a literature review].

: We demonstrate and discuss slowly progressive expanding hematoma (SPEH) in the basal ganglia, which expands over 2 weeks. To our knowledge, there have been only 5 cases of sudden-onset SPEH of the basal ganglia. To this, we add 3 cases admitted our hospitals because of putaminal hemorrhage within 1.5 hours of onset. All hematomas exhibited "2 components of hematoma sign" on initial CT scans, which we termed the "TCH sign" characterized as an anterolateral fluid portion and a posteromedial solid portion. Follow-up CT scans revealed gradual expansion of the fluid component of the hematoma without rebleeding for the subacute phase. Two cases were treated surgically. The first case, a 47-year-old man, underwent ultrasonically guided hematoma aspiration on day 17 and the second case, a 37-year-old man, underwent hematoma removal by craniotomy on day 23 after onset. Their postoperative courses were uneventful. The third case, a 57-year-old man, improved without surgical treatment and the hematoma dissolved completely within 2 months. To an extent, the TCH sign on a CT scan can be related to SPEH. We reviewed previous reports, including those an chronic expanding intracerebral hematomas and chronic encapsulated intracerebral hematomas, and concluded that it requires approximately 1 month for encapsulation of the hematoma to emerge. We suggest a possible progressive mechanism of SPEH. At first, the hematoma is divided into a fluid and a solid portion. Local generation of osmotically active molecules by clot degradation may allow intravascular fluid to escape into the fluid portion of the hematoma. Edema fluid with leakage via the disrupted blood-brain barrier may also aggravate the fluid portion of the hematoma. The continuing inflammatory response leads to the emergence of a hematoma capsule similar to the membrane observed in cases of chronic subdural hematoma, followed by the secondary causes of hematoma expansion. We discuss feasible timing and surgical treatment methods.