Causes

• Lesions due to herniation of the posteroinferior cerebellar artery, that affect the thalamic sensory nuclei and may cause severe dysesthetic (intractable) pain, usually in the presence of hemiplegia, and sometimes in the presence of choreoathetosis
• Suprathalamic lesions that involve the thalamocortical pathways, with:
  • Minimal involvement of pain, temperature, touch, and vibratory sensibility, and
  • A severe deficit in the discriminatory sensations that require cortical participation (called cortical sensory deficit), such as proprioception, two-point discrimination, localization of touch, and stereognosis
• Irritative lesions in the region of the post central gyrus, that initiate seizures which manifest as contralateral paresthesias
• Vascular lesions that affect the pons and medulla

Signs include the thalamic hand, which is sometimes observed in thalamic infarction and may present with or without thalamic pain

Treatment

• Drug therapy includes consideration of:
  • Anticonvulsants, such as phenytoin or carbamazepine for spasmodic pain
  • Tricyclic antidepressants and/or selective serotonin reuptake inhibitors (SSRIs), venlafaxine, and mexiletine
  • Fluphenazine with tricyclic or SSRI antidepressants
  • Fluphenazine alone, lidocaine, and calcitonin are considered controversial

• Other forms of therapy include:
  • Neuroablative procedures, which usually produce short-lived analgesic effects, such as:
    • Thalamotomy, the most common, which may cause loss of tactile and proprioceptive sensation
    • Neurectomy, rhizotomy, dorsal root entry zone lesions, anterolateral cordotomy, mesencephalotomy, and leukotomy
  • Stimulation procedures, which are not as effective for central pain, such as transcutaneous electric nerve stimulation, acupuncture, and stimulation of the dorsal column, periaqueductal and periventricular gray matter, thalamaus, and motor cortex