Intention Tremor - Mechanism

Mechanism

Intention tremors caused by normal, everyday activities, such as stress, anxiety, fear, anger, caffeine, and fatigue do not seem to result from damage to any part of the brain. These tremors instead seem to be a temporary worsening of a small tremor that is present in every human being. These tremors go away with time.

More permanent intention tremors are caused by damage to certain regions of the brain. The most common cause of intention tremors is damage to the cerebellum. The cerebellum is a part of the brain responsible for motor coordination, posture and balance. It is responsible for fine motor movements. When the cerebellum is damaged, a person has difficulty executing a fine motor movement, such as attempting to touch one's nose with one's finger. One of the most common ways for the cerebellum to become damaged is through the development of cerebellar lesions. The most common site for cerebellar lesions that lead to intention tremors has been reported to be the superior cerebellar peduncle, through which all fibers carrying information to the midbrain pass, and the dentate nucleus, which is also responsible for linking the cerebellum to the rest of the brain. Alcohol abuse is one typical cause of this damage to the cerebellum. The alcohol abuse causes degeneration of the anterior vermis of the cerebellum. This leads to an inability to process fine motor movements in the individual and the development of intention tremors. In Multiple Sclerosis, damage occurs due to demyelination and neuron death, which again produces cerebellar lesions and an inability for those neurons to transmit signals. Because of this tight association with damage to the cerebellum, intention tremors are often referred to as cerebellar tremors.

Intention tremors can also be caused as a result of damage to the brainstem or thalamus. Both of these structures are involved in the transmission of information between the cerebellum and the cerebral cortex, as well as between the cerebellum and the spinal cord, and then on to the motor neurons. When these become damaged, the relay system between the cerebellum and the muscle which it is trying to act upon is compromised, resulting in the development of a tremor.