The hypothalamospinal tract connects the thalamus to the ciliospinal center of the intermediolateral cell column in the spinal cord (T1, T2). It is found in the dorsolateral quadrant of the lateral funiculus, in the lateral tegmentum of the medulla, pons and midbrain. Lesions of the hypothalamospinal tract cause ipsilateral Horner's syndrome.[1]
Lesions of the posterior inferior cerebellar artery (PICA) lead to the so called lateral medullary syndrome, with ipsilateral Horner's Syndrome as the result of lesioning this nucleus.