Damage to the thalamus is most often associated with chronic pain, according to ATrain Education. The chronic pain disorder associated with damage to the thalamus is called thalamic pain or central pain syndrome.
The thalamus is the region of the brain that first receives and processes information from the sensory nerves, as ATrain Education notes. It takes that information and relays it to other regions of the brain. Thus, damage to the thalamus can cause changes in sensory perception, especially the perception of pain. Thalamic pain syndrome, the disorder most strongly associated with thalamus damage, is characterized by constant pain down one side of the body several weeks after a stroke. The pain is most often a burning sensation, though it may also be accompanied by a prickling sensation, or a sensation of tearing or of pressure. The pain ranges from mild to excruciating and can be intensified by cold or by touch.
The role of the thalamus in sensation can also cause the loss of feeling and even paralysis down one side of the body after a stroke, according to Stroke Awareness for Everyone. Fortunately, feeling and motor control can often be regained, unlike the paralysis and loss of feeling that result from damage to the spinal cord.
Damage to the thalamus is also implicated in some movement disorders. Sixty-two cases of people developing problems with movement after damage to the thalamus or subthalamuc region are presented in a 1994 paper in Movement Disorders. Most often, the movement disorders involved dystonia, or involuntary muscle contractions. This is probably because the thalamus is involved in relaying information on motor movement from one area of the brain to another, according to Dartmouth Medical School.
Thalamic damage can also cause insomnia and other sleep disorders. The thalamus is deeply involved in the wake-sleep cycle, as noted in a 1992 paper in the journal Neurology. Damage to the thalamus can permanently damage the ability to sleep.