Facial numbness can be caused by a variety of factors. The most common cause of this symptom is disruption or compression of the facial nerves. Conditions that affect these nerves include stroke, trauma, and tumors. Numbness may also be experienced in the face due to drug side effects, neurological phenomena, and some medical conditions, such as diabetes and neuropathy.
The most common cause of facial numbness is a stroke. A stroke causes damage to the brain from deprivation of oxygen and blood. A stroke will often cause numbness in some part of the body, depending on which parts of the brain were affected by the lack of oxygen. If the nerves connected to the face are deprived of oxygen, full or partial facial paralysis will result.
Nerve damage is another very common cause of facial numbness. Nerves are what tell the brain what sensations to experience and where. When nerves are damaged, they can cause pain or complete failure to produce sensation. Nerve damage can come about in a number of ways. Trauma from a blow to the head or neck can cause damage to the facial nerves severe enough to lose feeling. Certain medical conditions such as diabetes and neuropathy can also cause numbness in the face.
Occasionally, drug side effects can cause facial numbness. This is usually caused by drugs that work to inhibit neurotransmitters in the brain. This side effect is not very common, but inhibiting neurotransmitters comes at the risk of numbness to the whole body or one or two parts of the body, including the face.
Facial numbness can also be caused by stress-induced neck tension. The nerves that supply the face with feeling originate in the neck and shoulders. During stress, these muscles are some of the first to become tense. Long periods of this kind of tension can pinch these vessels and nerves, resulting in a loss of feeling in the face.
Facial numbness is also caused by migraines with an aura. This particular type of migraine is considered a neurological phenomenon. It describes a migraine with symptoms that occur 10 to 30 minutes before the headache begins. One of these symptoms is numbness in the face. Numbness can also affect the tongue or extremities. Migraines with an aura may also be experienced as visual hallucinations involving light, temporary blindness, and speech abnormalities.
Acoustic neuroma is another cause of facial numbness. It is a non-cancerous tumor, also called vestibular schwannoma and neurolemmoma, that grows on the eighth cranial nerve. This nerve can sometimes press on the nerves that control facial sensation and movement, which are the trigeminal nerve and the facial nerves, respectively. If they press on either of these nerves, numbness in the face can occur.