Blood supply of the thalamus and strokes

Nice illustration p 277 of Stroke Syndromes, ed by Bogousslavsky and Caplan, first edition


Polar artery of the thalamus (also tuberothalamic, anterior internal optic or premamillary pedicle) usually arises from the PCoA (posterior communicating artery) and supplies NOT the anterior nucleus but anteromedial and anterolateral thalamus, reticular nucleus, mammillothalamic tract, part of the ventral lateral nucleus, the dorsomedial nucleus, and the lateral aspect of the anterior thalamic pole. In one third, the thalamic subthalamic artery supplies these areas and the polar artery is missing.

Thalamic subthalamic arteries (paramedian thalamic, deep interpeduncular profunda, posterior internal optic, or thalamoperforating pedicle) arise from the P1 portion of the PCA (the part before the PCoA branches off) and in one third, both arise from one side or a common pedicle. They supply the posterior medial thalamus, including the rostral interstitial nucleus of the MLF, the posterior inferior portion of the DM nucleus, the nucleus parafascicularis, intralaminar nuclei and sometimes the mammillothalamic tract.

The thalamogeniculate arteries arise as a pedicle of 6-10 aa from P2 ambient cistern segment of the PCA and supply the ventrolateral thalamus including VPL, VPM, lateral part of CM and rostrolateral pulvinar.

Posterior choroidal aarise from the P2 ambient cistern after above and supply the pulvinar, posterior thalamus, geniculate bodies, and anterior nucleus.

Supply by a fifth branch, the anterior choroidal, is variable and of little consequence.

Strokes of:
1) Lateral thalamic of thalamogeniculate arteries have 3 types a) pure sensory-- paresthesia followed by pure hemisensory often slight affecting part of such as face/hand, face only, trunk, or upper and lower limbs . It often is dissociated, sparing pain and temperature and can lead to a severe thalamic pain syndrome in the anesthesia douloureuse of Dejerine and Roussy (1906) b) Sensorimotor-- same as above with hemiparesis and long tract signs due to involvement of adjacent capsule (see Dejerine/Roussy or Mohr 1977) c) "thalamic syndrome" a+b+interruption of EPS/cerebellar trats synapsing in the lateral thalamus (caplan 1988) with ataxia, oscillations, hypermetria, dydiadochokinesia and abnormal gait called "thalamic astasia." Hemisdystonia and posture of the hand "la main thalamique" is seen (Foix/Hillemand 1925a, Caplan 1988). Cognition is normal.

2) Polar artery strokes-- abulia, apathy slovenly (pseudofrontal), aphasia (if left sided) acute amnesia (verbal is left sided, visual memory if right sided, severe and permanent if bilateral). Occassionally a transient HP or HS loss occurs.

3) Paramedian thalamic-subthalamic arteries--triad of alteration of consciousness, neuropscyhological disturbance, and vertical gaze abnormality. Somnolence or coma may be due to intralaminar nuclei. Gaze is upgaze or combined up/downgaze palsy or skew deviation. Pure downgaze palsy is only found in bilateral paramedian infarcts. Later, apathy and amnesia, confabulations, temporary neglect, abnormal movements (asterixis, tremor or dystonia after delay of several weeks), blepharospasm, compulsive assumption of a sleeping posture, and utlization behavior.

4) Posterior choroidal-- visual field deficits due to LGB involvement with upper or lower quadrantanopsia, or more often, horizontal wedge shaped or tubular sectoranopias. Involvement of the pulvinar, posterior and anterior nuclei can also produce impaired pursuit movements of the eyes, mild HP or HS loss, dystonic movements, and neuropsychological symptoms such as aphasia, amnesia, abulia, and visual hallucinosis.