A focal neurologic deficit is a problem in nerve function that affects:

• A specific location -- such as the left face, right face, left arm, right arm, left leg, right leg, even just a small area such as just the tongue
• A specific function -- for example, speech may be affected, but not the ability to write

The problem occurs in the brain or nervous system. It may result in a loss of movement or sensation. The type, location, and severity of the change can indicate the area of the brain or nervous system that is affected.

In contrast, a non-focal problem is NOT specific -- such as a general loss of consciousness.

Focal neurologic changes can include any function. Sensation changes include paresthesia (abnormal sensations), numbness, or decreases in sensation. Movement changes include paralysis, weakness, loss of muscle control, increased muscle tone, and loss of muscle tone.

Other types of focal loss of function include:

• Speech or language difficulties such as aphasia or dysarthria (impaired speech and language skills), poor enunciation, poor understanding of speech, impaired writing, impaired ability to read or to understand writing, inability to name objects (anomia)
• Vision changes such as reduced vision, decreased visual field, sudden vision loss, double vision (diplopia)
• Neglect or inattention to the surroundings on one side of the body
• Loss of coordination, or loss of fine motor control (ability to perform complex movements)
• Horner's syndrome: one-sided eyelid drooping, lack of sweating on one side of the face, and sinking of one eye into the socket
• Poor gag reflex, swallowing difficulty, and frequent choking

• Stroke
• Brain tumor
• Cerebral palsy
• Disorders of a single nerve or nerve group (for example, see carpal tunnel syndrome)
• Infection
• Trauma
• Neurodegenerative illness
• Vascular malformation

Home care depends on the type and the cause of neurologic loss. (See the specific causative disorder.)

If any loss of movement, sensation, or function occurs, call your health care provider.

The medical history will be obtained and a physical examination performed.

Medical history questions documenting neurological deficits in detail may include:

• Where is the loss of function?
  • Right arm?
  • Right leg?
  • Left arm?
  • Left leg?
  • Another location (be specific)?
• What deficits are present?
  • Loss of vision?
  • Numbness?
  • Loss of movement?
  • Loss of strength?
  • Loss of hearing?
  • Speech problem or language problem?
  • Other (be specific)?
• What other symptoms are also present?

The physical examination will include a detailed examination of nervous system function.

Diagnostic tests vary depending on other symptoms and the suspected cause of the nerve function loss.