Maintaining the body's physical balance involves multiple types of sensory input and the coordinated activity of several areas of the brain. The eyes, the vestibular system of the inner ear and sensory nerves in the skin, muscles and joints provide continuous input to the brain to maintain body balance. Processing of sensory input and corresponding control of muscle activity to maintain balance occurs moment-to-moment. Abnormalities in any of the many structures involved in this intricate process can lead to balance problems.
Vestibular Disorders
As explained by the National Institute on Deafness and Other Communication Disorders, the inner ear houses the vestibular system, comprised of the otoliths and the semicircular canals. Together, these structures detect linear and rotational movements of the head. This information proves critical in maintaining body balance, as evidenced by the effects of disturbances in this system. Diseases that disrupt the function of the vestibular system cause vertigo, a phantom sense of whirling motion similar to that experienced with severe alcohol intoxication. The intensity of this symptom typically leaves the sufferer no option but to lie down and remain motionless. Disorders that disrupt balance by adversely affecting vestibular system function include Ménière's disease, perilymph fistula, labyrinthitis, vestibular neuronitis and benign paroxysmal positional vertigo.
Peripheral Neuropathy
The brain depends on continuous input from sensory nerves in the body to determine its position in space and to maintain balance. Pressure-sensitive nerves of the feet, ankles and leg joints help the brain determine where the body weight rests. Position sense nerves in the muscles and joints provide similarly crucial information. Diseases of the nerves outside the brain and spinal cord--peripheral neuropathies--can disrupt the regular transmission of positional information between the body and brain. As noted by the University of Chicago Center for Peripheral Neuropathy, loss of balance and coordination can be a symptom of peripheral neuropathy. Many conditions can cause peripheral neuropathy and an associated balance disturbance, including diabetes mellitus, rheumatoid arthritis, sarcoidosis, systemic lupus erythematosus, vitamin B12 deficiency, celiac disease, leprosy, chronic kidney disease and HIV/AIDS.
Cerebellar Disorders
The cerebellum serves as the brain's master control center of body balance and coordination. All sensory input regarding body position and commands from higher centers of the brain to initiate movement pass through the cerebellum, which synchronizes the muscle responses into smooth, coordinated movements. The National Institute of Neurological Disorders and Stroke explains that cerebellar function abnormalities lead to marked balance and coordination disturbances. Walking difficulties often prove an early symptom with degenerative cerebellar disorders. Diseases and conditions that may disrupt cerebellar function include stroke, brain tumor, thiamine deficiency, Creutzfeldt-Jakob disease, multiple sclerosis, Friedreich's ataxia, Wilson's disease and cerebral palsy.
References
- MayoClinic.com: Ataxia, Causes
- National Institute on Deafness and Other Communication Disorders: Balance Disorders
- Vestibular Disorders Association: Specific Vestibular Disorders
- National Institute of Neurological Disorders and Stroke: Peripheral Neuropathy, Symptoms
- University of Chicago Center for Peripheral Neuropathy: Symptoms
