Thalamic haemorrhage

Thalamic haemorrhage is usually considered a single entity although the thalamus is composed of anatomically as well as functionally discrete subregions receiving blood from different arteries. The clinical features vary according to the intrathalamic location of the haematomas and the bleeding artery. We investigated the impact of haematoma location and vascular territory on the clinical symptoms and signs, neuro-imaging findings and clinical courses of patients with thalamic haemorrhages by a retrospective analysis of 175 consecutive patients with thalamic haemorrhage. Based on the neuro-imaging findings we classified thalamic haematomas into four regional types and one global type according to the primary bleeding sites: (i) anterior type occurring in the territory of the tuberothalamic arteries, (ii) posteromedial type occurring in the territory of the thalamic-subthalamic paramedian arteries, (iii) posterolateral type occurring in rite territory of the thalamogeniculate arteries, (iv) dorsal type occurring in the territory of the posterior choroidal arteries and (v) global type occupying the entire area of the thalamus. We studied the clinical and neuroimaging characteristics of each type. Eleven patients (7%) had the anterior type; these were the smallest haematomas and often ruptured into the anterior horn of the lateral ventricle. The major clinical signs were acute behavioural abnormalities; the clinical course was usually benign. Twenty-four patients (14%) had the posteromedial type in which haematomas often ruptured into the third ventricle, causing marked hydrocephalus, and often extended mediocaudally, involving the mesencephalon. The prognoses of this type depended on the presence of mesencephalic involvement which was associated with the worst outcome among the types even if the size of the haematoma itself was not large. The posterolateral type was most frequent (77 patients, 44%) and was characterized by large haematomas, rupture into the posterior horn of the lateral ventricle and frequent extension into the posterior limb of the internal capsule. Clinical signs included marked sensory and motor signs, hemineglect in right-side haematomas and language abnormalities with left-side haematomas. The case fatality with this type was relatively high (35%) and permanent neurologic sequelae frequently resulted. In the dorsal type (32 patients, 18%) haematomas were best visualized at the level of the body of the lateral ventricle on CT scans. The size was moderate and haematomas often extended posterolaterally into the adjacent subcortical white matter: Sensory and motor signs were common and about one third of the patients were first misdiagnosed as having lacunar infarcts. The prognoses were excellent The global type (31 patients, 18%) of thalamic haemorrhage was clinically and radiologically very similar to the posterolateral type except that the haematomas were too large to define the bleeding focus. Severe sensory and motor signs were almost always present. In this type 25 patients died (the case fatality was 81%).