CLINICAL CASES

TRIGEMINAL NEURALGIA

A 55 year old white male presents complaining of severe pain involving his lips, gums, and cheeks. He describes the pain as sharp and stabbing, and rates it a 10 out of 10 on the pain scale. It is intermittent, with individual episodes lasting only seconds, but occurring throughout the day and night. He reports that these episodes started approximately two weeks ago. He notes that the episodes are sometimes triggered by chewing and says he has been eating less for fear of the pain. He has not noticed any facial weakness or numbness.

DISCUSSION: Trigeminal neuralgia, a.k.a. "tic douloureux" for the wince or "tic" it causes in response to pain, is a condition characterized by sudden, recurrent episodes of excruciating facial pain typically lasting only seconds. Though brief, these episodes often occur in rapid succession throughout the day and night causing patients significant distress. Trigeminal neuralgia usually occurs in patients over 50, with symptoms lasting for several weeks at a time. Intermittent remission and relapse may occur over many years. Pain can occur along any branch of the trigeminal nerve, though V1 (the ophthalmic nerve) is rarely involved. Stimulation of "trigger zones" such as the corner of the mouth, side of the nose, oral mucosa, etc. characteristically precipitate painful episodes. Patients may alter the way they chew, wash their face, shave, etc. to avoid these triggers. Trigeminal neuralgia is not associated with facial numbness or weakness and the majority of cases are of unknown etiology.

HERPES ZOSTER

A 70 year old black male presents complaining of a crusted rash involving the left side of his face (see picture at left). He first noticed itching, tingling, and then severe burning in the area approximately two weeks ago. He reports that this lasted for several days before the area began to erupt with small blisters with red edges. The blisters then became cloudy and dried up over the past week leaving him in his current state. He describes the changing rash as similar to chickenpox, which he remembers having as a child. He is still having pain in the area. He notes that he had "a bad flu" just before this all started.

DISCUSSION: Herpes zoster, a.k.a. "shingles", is characterized by altered sensation, pain, and cutaneous eruption in a dermatomal distribution (along a sensory nerve). The majority of cases involve thoracic dermatomes (usually T5-T10) and therefore the patient's chest and back. The trigeminal nerve can also be involved, with the painful rash typically occurring in the distribution of the ophthalmic nerve (V1) - see the picture which accompanies this case. Herpes zoster occurs in patients who have had the chickenpox (you may have heard chickenpox referred to as "varicella" - the full name for the virus that causes both chickenpox and shingles is "VZV" or varicella-zoster virus). With initial infection (when the patient gets chickenpox), the virus travels along the trigeminal nerve from the skin to the trigeminal ganglion where it becomes latent. In some individuals, the virus may become reactivated and travel in reverse from the ganglion back to the skin where it causes symptoms. Exactly how and why the virus reactivates in certain individuals is poorly understood, but the incidence of herpes zoster increases with age and in patients who are immunosuppressed. While the pain associated with herpes zoster typically resolves with the rash, some patients (particularly the elderly) develop persistent, often debilitating pain. This syndrome is known as "postherpetic neuralgia".

TUMOR SPREAD ALONG INFRAORBITAL NERVE

A 65 year old white female presents complaining of a mass over her left eye. She reports that the mass started as a small bump on her lower left eyelid approximately five years ago, and has gradually gotten larger. The mass has never been painful, but the patient does report numbness and occasional tingling under her left eye that has worsened as the mass has increased in size. Recently, she has noted more extensive numbness on the left side of her face. Additionally, the patient recalls gradual changes in her vision including double vision initially, and then progressively worsening visual acuity to the point where she is now blind in her left eye. Pre-operative, intra-operative, and post-operative pictures (after flap reconstruction) are shown.

DISCUSSION: Tumors may spread from one area to another by several routes including blood (hematogenously), lymphatics, and direct extension. As tumors disseminate by direct extension, they may track along nerves and blood vessels (neurovascular spread). This patient had a basal cell carcinoma (the most common type of skin cancer) which tracked centrally along the infraorbital nerve. Basal cell carcinomas rarely metastasize, and typically are easily removed with minor surgery when identified early. However, mass effect from a basal cell carcinoma can cause severe symptoms if there is a significant delay before medical attention is sought. In this patient, encroachment of nearby structures such as sensory fibers within the infraorbital and zygomatic nerves, ocular muscles, and the orbit caused numbness, double vision (diplopia), and blindness, respectively. The patient's left eye was sacrificed during surgery in order to remove this large tumor completely (see intra-operative picture). Not only skin cancer spreads along nerves. For example, a meningioma (a tumor arising from the membranes lining the brain and spinal cord) might track along branches of the trigeminal nerve to the skin in the opposite direction.

REFERENCES

Photographs courtesy of Scott P. Stringer, MD, MS, FACS, Professor and Vice-Chairman, Department of Otolaryngology, University of Florida College of Medicine

Bailey, Byron J., et al. (Eds.). (1998). Head & Neck Surgery - Otolaryngology (2nd ed.). Philadelphia, PA: Lippincott-Raven. Pgs. 294-295.

Fauci, A. S., et al. (Eds.). (1998). Harrison's Principles of Internal Medicine (14th ed.). New York: McGraw-Hill. Pgs. 2377, 2445-2446.