Facial numbness is a distressing symptom most commonly limited to one side of the face, although both sides are sometimes affected. The numbness can manifest as reduced sensitivity to a complete lack of sensation. Facial numbness occurs with a wide range of medical conditions, some much more serious than others. The specific part of the face affected and the presence or absence of accompanying signs and symptoms help narrow the lengthy list of possible culprits.
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Traumatic Nerve Damage
The trigeminal nerve -- also known as cranial nerve V or CN V -- carries sensation signals from the face and front of the scalp to the brain, where they are interpretted. Traumatic damage to any of the three branches of this nerve can lead facial numbness. This might occur due to a facial or skull injury, or accidental nerve injury during a dental procedure or surgery involving the face or brain. The three branches of CN V on each side of the face and the areas they innervate are:
- Ophthalmic nerve -- forehead, upper eyelid, front of the eyeball, lining of the top and bottom eyelids, and the center part of the nose
- Maxillary nerve -- apples of the cheeks, frontal temple area, side and lining of the nose, upper lip, upper jaw, upper teeth, and the roof of the mouth
- Mandibular nerve -- lower lip and chin, cheek and temple area near the front of the ear, external ear, lining of the lower mouth, and the front of the tongue
Nontraumatic Nerve Damage
A variety of ailments can lead to nontraumatic trigeminal nerve damage and facial numbness. Longstanding diabetes can damage nerves anywhere in the body including branches of CN V, although this is uncommon. Sickle cell disease can cause damage when mishapen red blood cells block capillaries and deprive the nerve(s) of oxygen. A molar tooth abscess can potentially damage a branch of CN V by compressing it. Head and neck, facial skin cancers, and cancers that spread from elsewhere in the body can cause facial numbness if they compress or invade a branch of CN V.
Facial numbness can accompany certain cranial nerve disorders. Bell palsy, for example, primarily affects the facial nerve causing temporary paralysis on one side of the face. For reasons that are incompletely understood, the trigeminal nerve can also be involved leading to facial numbness on the affected side. Another condition called trigeminal neuralgia is characterized by brief but excruciating shooting pains in the face. Between these episodes, the affected side of the face typically exhibits decreased sensation.
Central Nervous System Disorders
Several disorders of the central nervous system -- the brain and spinal cord -- can potentially cause facial numbness. Tumors involving the brainstem might cause this symptom, which is usually accompanied by other signs and symptoms that vary depending on the exact location and size of the growth. Acoustic neuroma, a noncancerous tumor of the nerve that carries signals betweeen the inner ear and brain, can cause facial numbness and weakness along with hearing loss, ringing in the affected ear and a spinning sensation.
Stroke and a transient ischemic attack -- commonly known as a TIA or mini stroke -- are important considerations with sudden facial numbness. Other signs and symptoms are usually present, such as one-sided drooping of the jaw, hoarseness, involuntary eye movements, incoordination or generalized loss of body sensation. Multiple sclerosis can also cause facial numbness, although this is uncommon.
The extensive list of possible causes of facial numbness are too numerous to cover exhaustively in a brief article. Some considerations in addition to those conditions already mentioned include:
- Bleeding into the brainstem
- Brainstem blood vessel malformation
- Cholesteatoma, a noncancerous middle ear tumor
- Pituitary gland tumor
- Certain drugs, such as cocaine and the gout medication allopurinol (Lopurin)
- Certain toxins, such as fertilizers, pesticides and arsenic
- Brass instrument (trumpet, tuba or French horn) neuropathy, a cause upper lip numbness
- Rarely, systemic lupus erythematosus or rheumatoid arthritis
Warnings and Precautions
See your doctor as soon as possible if you experience isolated facial numbness that develops gradually. Seek immediate medical care if you develop sudden facial numbness associated with a traumatic injury to your face, neck or skull, or if you experience other warning signs or symptoms, including:
- Sudden, severe neck pain or headache
- Sudden visual changes, such as vision loss or double vision
- Sudden dizziness or a spinning sensation
- Numbness, weakness or paralysis on one side of the body
- Slurred speech, difficulty swallowing or drooling
- Confusion, agitation, drowsiness or other mental changes
- Decreased coordination or difficulty walking
- Unequal pupil size
- Involuntary eyeball movements
- Drooping jaw or upper eyelid
REFERENCES & RESOURCES
- Neupsy Key: Approach to the Patient With Facial Numbness
- Journal of the Canadian Dental Association: Management of Unilateral Facial Numbness
- Evidence-Based Medicine Consult: Dermatomes of the Face
- Dartmouth College: Evaluation of the Patient With "Numbness"
- DocNeuro.com: Facial Numbness
- Mayo Clinic: Numbness: Causes