A neurologist treats disorders related to the central and peripheral nervous system, such as the brain, spinal cord, cranial nerves, peripheral nerves, nerve roots, autonomic nervous system, neuromuscular junctions, and muscles. Common disorders in the nervous system include:
• Epilepsy: a cognitive disorder that occurs due to abnormal brain electrical activity, leading to sudden recurrent and involuntary seizures and unconsciousness.
• Alzheimer's disease (and other dementia-related diseases): gradual mental decline that occurs due to brain damage.

• Stroke (and other brain and vascular diseases): occurs when blood clots or ruptured blood vessels prevent oxygen and nutrients from reaching the brain.
• Migraine (and other headache disorders): severe and recurrent headaches often accompanied by nausea and visual disturbances.
• Multiple sclerosis (MS): a chronic disease that occurs due to damage to the nerve cells in the brain and spinal cord, with symptoms including numbness, speech and muscle weakness, visual disturbances, and excessive fatigue.
• Parkinson's disease: a progressive disease characterized by symptoms such as tremors, muscle stiffness, slow movements, and uncoordinated posture. This condition involves degeneration of the basal ganglia of the brain and a decrease in dopamine.
• Brain tumor: an abnormal accumulation of cells in the brain that leads to cognitive dysfunction.
• Brain injury (and other neurosurgical conditions): damage to the brain from external forces that sometimes results in temporary or permanent changes in cognitive, physical, or psychosocial functioning.
• Tourette syndrome (and other disorders in normal function): a cognitive disorder characterized by involuntary tics, involuntary utterances of obscenities, and the use of offensive language.
• Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease): progressive degeneration of the motor neurons in the central nervous system, leading to muscle atrophy and paralysis.