Neurology

Epilepsy is a chronic neurological condition characterized by recurrent seizures that are caused by abnormal cerebral nerve cell activity. There is a distinction between a patient who has one seizure and a patient who has epilepsy. Epilepsy can be classified as either idiopathic or symptomatic.

Many abnormalities of the nervous system can result in seizure activity. Seizures can also occur in the normal nervous system when its metabolic balance is disturbed. The cause (etiology) of epilepsy may be not clearly known (idiopathic) or related to a particular disease state. About 35% of all cases of epilepsy have no clearly definable cause.

Strokes, or brain attacks, are a major cause of death and permanent disability. They occur when blood flow to a region of the brain is obstructed and may result in death of brain tissue.

There are two main types of stroke: Ischemic and hemorrhagic. Ischemic stroke is caused by blockage in an artery that supplies blood to the brain, resulting in a deficiency in blood flow (ischemia). Hemorrhagic stroke is caused by the bleeding of ruptured blood vessels (hemorrhage) in the brain.

During ischemic stroke, diminished blood flow initiates a series of events (called ischemic cascade) that may result in additional, delayed damage to brain cells. Early medical intervention can halt this process and reduce the risk for irreversible complications.

Headache is a term used to describe aching or pain that occurs in one or more areas of the head, face, mouth, or neck. Headache can be chronic, recurrent, or occasional. The pain can be mild or severe enough to disrupt daily activities. Headaches involve the network of nerve fibers in the tissues, muscles, and blood vessels located in the head and at the base of the skull.

A migraine headache is a throbbing or pulsating headache that is often one sided (unilateral) and associated with nausea; vomiting; sensitivity to light, sound, and smells; sleep disruption; and depression. Attacks are often recurrent and tend to become less severe as the migraine sufferer ages.

Multiple sclerosis (MS) is an inflammatory, chronic, degenerative disorder that affects nerves in the brain and spinal cord. Myelin, the fatty substance that surrounds and insulates nerves and facilitates the conduction of nerve impulses, is the initial target of inflammatory destruction in multiple sclerosis.

MS is characterized by intermittent damage to myelin, called demyelination. Demyelination causes scarring and hardening (sclerosis) of nerve tissue in the spinal cord, brain, and optic nerves. Demyelination slows conduction of nerve impulses, which results in weakness, numbness, pain, and vision loss.

Because different nerves are affected at different times, MS symptoms often worsen (exacerbate), improve, and develop in different areas of the body. Early symptoms of the disorder may include vision changes (e.g., blurred vision, blind spots), numbness, dizziness, and muscle weakness.

MS can progress steadily or cause acute attacks (exacerbations) followed by partial or complete reduction in symptoms (remission). Most patients with the disease have a normal lifespan.

Parkinson's disease is a chronic, progressive neurodegenerative movement disorder. Tremors, rigidity, slow movement (bradykinesia), poor balance, and difficulty walking (called parkinsonian gait) are characteristic primary symptoms of Parkinson's disease.

Idiopathic Parkinson's disease is the most common form of parkinsonism, which is a group of movement disorders that have similar features and symptoms. Parkinson's disease also is called idiopathic Parkinson's because the cause for the condition is unknown. In the other forms of parkinsonism, a cause is known or suspected.

Parkinson's results from the degeneration of nuclei in a number of dopamine-producing nerve cells in the brainstem. Dopamine is a neurotransmitter that stimulates motor neurons, which are nerve cells that control the muscles. When dopamine production is depleted, the motor system nerves are unable to control movement and coordination.

Parkinson's disease patients have lost 80% or more of their dopamine-producing cells by the time symptoms appear. In searching for a cause for Parkinson's disease, most of the attention has focused on areas of the brain called the substantia nigra and the locus coeruleus.

Alzheimer's disease (AD) is an irreversible, progressive disorder in which brain cells (neurons) deteriorate, resulting in the loss of cognitive functions, primarily memory, judgment and reasoning, movement coordination, and pattern recognition. In advanced stages of the disease, all memory and mental functioning may be lost.

The condition predominantly affects the cerebral cortex and hippocampus, which lose mass and shrink (atrophy) as the disease advances.

Movement disorders are neurological conditions that affect the speed, fluency, quality, and ease of movement. Abnormal fluency or speed of movement (dyskinesia) may involve excessive or involuntary movement (hyperkinesia) or slowed or absent voluntary movement (hypokinesia).

Movement disorders include the following conditions:

• Ataxia (lack of coordination, often producing jerky movements)
• Dystonia (causes involuntary movement and prolonged muscle contraction)
• Huntington's disease (also called chronic progressive chorea)
• Multiple system atrophies (e.g., Shy-Drager syndrome)
• Myoclonus (rapid, brief, irregular movement)
• Parkinson's disease
• Progressive supranuclear palsy (rare disorder that affects purposeful movement)
• Restless legs syndrome (RLS) and reflex sympathetic dystrophy/periodic limb movement disorder (RSD/PLMD)
• Tics (involuntary muscle contractions)
• Tourette's syndrome
• Tremor (e.g., essential tremor, resting tremor)
• Wilson disease (inherited disorder that causes neurological and psychiatric symptoms and liver disease)
• Common dystonias include spasmodic torticollis, which affects muscles of the head, face, and neck, and blepharospasm, which causes involuntary closing of the eyelids.

Neuromuscular disease is a very broad term that encompasses many conditions. This includes disease as the result of intrinsic muscle pathology, nerve pathology, or the communication between muscle and nerves.