Neuritis refers to an inflammation of a nerve with pain and tenderness, anesthesia and paresthesia, paralysis, wasting, and disappearance of the reflexes. The XIIth cranial nerve is one of twelve pairs of nerves connected with the brain. It is the motor nerve to the tongue supplying the ipsilateral muscles, which provide tongue movement.

In some cases, the cause of neuritis may be unknown. Identified causes may include: trauma; tumors; hemorrhage into a nerve; lesions; continuous pressure on a nerve; exposure to cold or radiation; viruses; or infectious disease such as Lyme disease. Other contributing factors may include: systemic malignancy; leprosy; metabolic diseases such as diabetes mellitus; collagen blood disorders; toxic agents; certain medications; nutritional deficiencies; metabolic disorders such as alcoholism; and genetics.

Symptoms may vary depending on the form of neuritis and the location of the lesion along the nerve. Manifestations may include: neuralgia; hyperesthesia; paresthesia; dysesthesia; hypesthesia; anesthesia; muscle atrophy; weakness; paralysis; lack of reflexes; deviation of the tongue; fasciculation; dysarthria; and difficulty eating.

Diagnostic measures may include: complete history; physical and neurological examinations; motor tests; blood studies; spinal tap; computed tomography (CT) scan; magnetic resonance imaging (MRI); and electromyography (EMG).

Treatment may include management of the underlying disorder. Other treatment measures may include: medications for pain; anti-inflammatory drugs; antibiotics; vitamin therapy; and physical therapy. Nutritional intervention, and physical and speech therapies may also be included in the treatment plan. Other treatments for symptoms of affected neighboring nerves may be indicated.

Regeneration of the nerve may depend on the degree and site of injury. The closer the injury is to the central nervous system (CNS), regeneration of a severely damaged nerve is less likely to occur. Atrophy and fasciculation may develop weeks to months following nerve injury. Other possible residuals include: the potential for paralysis of the nerve; decline in nutritional status; and possible injury to neighboring nerves.

• This disease shall be granted service connection although not otherwise established as incurred in or aggravated by service if manifested to a compensable degree within the applicable time limits under 38 CFR 3.307 following service in a period of war or following peacetime service on or after January 1, 1947, provided the rebuttable presumption provisions of 38 CFR 3.307 are also satisfied [38 CFR 3.309 [Disease subject to presumptive service connection], 38 CFR 3.309(a). [chronic disease].

• Dependent upon loss of motor function of tongue.

• Disability from lesions of peripheral portions of first, second, third, fourth, sixth, and eighth nerves will be rated under the Organs of Special Sense. The ratings for the cranial nerves are for unilateral involvement; when bilateral, combine but without the bilateral factor.

• Neuritis, cranial or peripheral, characterized by loss of reflexes, muscle atrophy, sensory disturbances, and constant pain, at times excruciating, is to be rated on the scale provided for injury of the nerve involved, with a maximum equal to severe, incomplete, paralysis. See nerve involved for diagnostic code number and rating. The maximum rating which may be assigned for neuritis not characterized by organic changes referred to in this section will be that for moderate, or with sciatic nerve involvement, for moderately severe, incomplete paralysis. (38 CFR 4.123)