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A focal neurologic deficit is a problem in nerve, spinal cord, or brain function that affects a specific location, such as the left face, right arm, or even a small area such as the tongue.

It also refers to any problem with a specific nervous system function such as memory or emotion.

The type, location, and severity of the problem 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.

A focal neurologic problem can affect any function:

• Movement changes include paralysis, weakness, loss of muscle control, increased muscle tone, loss of muscle tone, or involuntary movements (such as tremor)
• Sensation changes include paresthesia (abnormal sensations), numbness, or decreases in sensation

Other examples of focal loss of function include:

• Horner's syndrome: one-sided eyelid drooping, lack of sweating on one side of the face, and sinking of one eye into the socket
• Inattention to the surroundings or a part of the body (neglect)
• Loss of coordination, or loss of fine motor control (ability to perform complex movements)
• Poor gag reflex, swallowing difficulty, and frequent choking
• Speech or language difficulties such as aphasia (a problem understanding or producing words) or dysarthria (a problem making the sounds of words), 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)

Anything that damages or disrupts any PART of the nervous system can cause a focal neurologic deficit. Examples include:

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

Home care depends on the type and the cause of neurologic loss. (Refer to the specific disorder causing the problem.)

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

The health care provider will take your medical history and perform a physical examination.

Medical history questions detailing neurological deficits may include:

• When did the problem start and how fast is it changing?
  • Was it sudden or gradual?
  • Has it worsened over seconds, minutes, hours, days, or months?
  • How long have you had the problem?
• Where is the loss of function?
  • Left arm?
  • Left leg?
  • Right arm?
  • Right leg?
  • Another location (be specific)?
• What deficits are present?
  • Loss of hearing?
  • Loss of movement?
  • Loss of strength?
  • Loss of vision?
  • Numbness?
  • Speech problem or language problem?
  • Other (be specific)?
• What other symptoms do you have?

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. Tests used ot evaluate focal neurologic deficits are aimed at locating the place in the nervous system that is involved. Common examples are:

• CT scan of the back, neck, or head
• EMG (electromyogram)/NCV (nerve conduction velocities)
• MRI of the back, neck, or head

Neurological deficits - focal

Griggs RC, Jozefowicz RF, Aminoff MJ. Approach to the patient with neurologic disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier. 2007: chap 418.

Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.