Dr. Bogousslavsky of the Genolier Swiss Medical Network has no relevant financial relationships to disclose.)
This article includes discussion of thalamic hemorrhage, posterolateral hematomas, dorsal hematomas, posterior-dorsal hematomas, medial hematomas, and anterolateral hematomas. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
The thalamus is involved in about 1 of every 6 nontraumatic intracerebral hemorrhages. Hemisensory loss, decreased level of consciousness, and hemiparesis are the usual manifestations of thalamic hemorrhage; nevertheless, depending on hematoma size and selective or global involvement of the different thalamic nuclei and neighboring structures, virtually any clinical neurologic finding may be seen in the setting of thalamic hemorrhages. In this article, the authors thoroughly address the broad clinical spectrum in terms of the intrathalamic location of both large and small bleedings. They also summarize the epidemiology, etiology, diagnostic workup, prognosis, and latest medical and surgical treatment options for thalamic hemorrhages.
• Thalamic hemorrhage is the second most common location of nontraumatic intracerebral hemorrhage, accounting for 10% to 15% of all hemorrhages.
• The clinical picture depends entirely on hematoma size, selective or global involvement of the different thalamic nuclei, and the involvement of neighboring structures.
• Arterial hypertension is the most common etiology, regardless of topographic location and hematoma size.
• Treatment is, for the most part, supportive medical care, including timely blood-pressure control.
Historical note and terminology
During the early decades of the twentieth century, French neurologists (particularly Dejerine, Foix, and their colleagues) made important contributions concerning the vascular anatomy and pathology of the thalamus, including the description of clinical manifestations resulting from lesions at different vascular territories (Dejerine and Roussy 1906; Foix and Hillemand 1925). At the time, the so-called “thalamic vascular syndrome” was defined as a persistent contralateral hemianesthesia affecting both superficial and deep sensory modalities, a transient mild hemiparesis, and hemiataxia, with possible subsequent development of intolerable pain and choreoathetotic movements in the affected limbs (Dejerine and Roussy 1906). Some years after the initial description of the thalamic syndrome, Lhermitte and Baudouin provided some clinical findings that helped to discriminate between ischemic and hemorrhagic lesions of the thalamus (Lhermitte 1925).
Traditionally, thalamic hemorrhages, along with those located in the caudate and putamen, were considered to be basal ganglionic hemorrhages. In 1959, however, CM Fisher pointed out abnormalities of pupillary and oculomotor function observed in 13 patients with thalamic hemorrhages out of 102 patients with pathologically confirmed intracerebral hemorrhage. Fisher also found greater sensory deficit than motor dysfunction, as well as speech or behavioral manifestations resulting from the involvement of the left or right thalamus, respectively (Fisher 1959).
The introduction of the CT scan 40 years ago and, more recently, of brain MRI technology has made it possible to identify small hematomas, describe clinical subtypes of thalamic hemorrhages, and improve insight into the function of the different thalamic nuclear regions.
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