12.0: Cranial neuralgias, nerve trunk pain, and deafferentation pain
12.1: Persistent (in contrast to tic-like) pain of cranial nerve origin

Under this heading will be discussed atypical facial pain and other neuralgias not listed in the categories below. In the IHS classification, pain in and around the eye caused by conditions such as optic neuritis, herpes zoster, post-herpetic neuralgia in the Tolosa-Hunt syndrome are described. I have chosen to discuss these elsewhere as noted. First, the condition we discuss is atypical facial neuralgia.

Atypical facial neuralgia

Not all complaints of pain about the face and head can be separated into the various syndromes discussed above. In any large group of patients with facial pain, there are some in whom neither the cause nor the appropriate management can be determined (McArdle, 1970). According to White and Sweet (1969), individuals afflicted with this atypical form of facial neuralgia tend to show the following characteristics. (1) Pain is not limited to an area supplied by a single nerve, but spreads to zones of several sensory cranial, or cervical and cranial, nerves. (2) Pain is not confined to one side of the face; it often spreads to both sides. (3) Pain is constant rather than paroxysmal, lasting without letup for days or months. (4) External stimuli, movement, or other activity of the patient do not precipitate an attack or aggravate the pain. (5) Discomfort is referred to deep, rather than superficial, tissues; the patient may describe his pain as ``gripping,'' ``drawing,'' ``pulling,'' ``boring,'' or ``bursting.'' (6) Tendency toward drug addiction is great. (7) A neurotic or neuropathic personality is usually associated. According to Lascelles (1966), such individuals often have an obsessive, rigid personality and features of an atypical depression with agitation, irritability, sleep disturbance, and mood swings.

None of the foregoing criteria is essential to the diagnosis. Pain arising from deep seated infections or from tumors of the face, head, or cranial cavity may have similar characteristics, so that thorough studies are required to eliminate these potential etiologies (O'Connell, 1978; Destee et al., 1980). Differential diagnosis of atypical neuralgia should also include temporal arteritis, temporomandibular joint neuralgia, and pain from dental sources (Symonds, 1956).

Neurosurgeons have attempted to give these patients relief by sectioning a variety of cranial and autonomic peripheral nerves; however, the choice of the proper nerve is difficult. Nearly all of the lower cranial nerves communicate with one another at some point and have abundant connections with cervical and sympathetic nerves as well. Pathways that may be taken by pain fibers wandering through this plexiform maze seem to be limitless. In fact, every conceivable type of peripheral and central operative procedure including frontal lobectomy has been attempted singly or in combination to afford these patients relief. Many procedures have provided temporary amelioration of symptoms, but long term results have been consistently disappointing. For this reason, Schott (1980) has suggested the use of ``noninvasive'' methods of management of atypical facial pain including the use of local cold applications, subcutaneous infiltration or peripheral nerve blocks with local anesthetic, acupuncture, transcutaneous electric stimulation, sympathetic blocks, non-narcotic analgesics, psychotropic drugs, and psychotherapy or other psychiatric treatment. At The Johns Hopkins Hospital, Dr. Melvin Epstein has experienced good results in such patients with transcutaneous electric stimulation.

Raskin describes atypical facial pain as a continuous, unilateral, deep, aching pain, sometimes with a burning component. However, deep, dull continuous pain is the type commonly encountered in a variety of disease states. Some of these patients eventually turn out to have disorders such as nasopharyngeal carcinoma or squamous cell carcinoma of the facial skin that has migrated perineurally intracranially (Morris and Joffe, 1983). In these two latter instances, facial pain may antedate cranial nerve dysfunction by several months. Therefore, a better designation for this syndrome is facial pain of unknown cause; as knowledge is advanced, other causes of pain will undoubtedly be uncovered. A significant number of patients with atypical facial pain have had infections at previous tooth extraction sites (Roberts and Pearson, 1979; Ratner et al, 1979).

Post-Traumatic Facial Pain

More than half the patients with non-descript facial pain report its onset after trauma to the face, often surgical trauma. Orbital enucleations, sinus procedures, and complicated dental extractions are the most common procedures that antedate the appearance of pain. Fortunately, for the large majority of the patients, their pain problems is self-limited; within 1 to 5 years it subsides whether symptomatic treatment is effective or not (Raskin, unpublished observations). The mechanism underlying this disorder presumably involves activation or central pain transmission pathways; how and why this occurs remains to be elucidated.

Facial (Geniculate) Ganglion Neuralgia From Herpes Zoster: The   Ramsay Hunt Syndrome

Pain in the ear associated with herpes zoster of the external auditory canal or of the ear, and followed by facial paralysis, represents the syndrome of the geniculate ganglion described by Hunt (1907).

Although not the first to attribute sensory function to the facial nerve, his extensive publications beginning early in the 20th century directed attention to the distribution of sensory fibers from the facial nerve within the ear. He obtained much of his information from the clinical study of patients with herpes zoster oticus, concluding that the location of their vesicular eruption and neuralgic pain indicated the area of cutaneous sensory innervation supplied by the seventh nerve. His last publication (1937) contains diagrams depicting these sensory fields (Figure 36.13). He suggested that facial sensory fibers to the external ear emerge with the facial trunk at the stylomastoid foramen and join the auricular branch of the vagus nerve and the posterior auricular nerve before being distributed to the skin (Figure 36.14. Failure of a complete facial nerve lesion to provide more than relative hypesthesia in the ``herpes zoster zone'' of the ear was attributed by Hunt to the considerable intermingling of sensory fibers from the trigeminal, facial, glossopharyngeal, vagus, and upper cervical nerves.

Several early observers, including Hunt (1937), also recognized a contribution of the facial nerve to deep sensation of the face (Figure 36.15). Cushing (1904) noted retention of a crude form of tactile sensation on the anterior two-thirds of the tongue after Gasserian ganglionectomy. He attributed this sensation to the facial nerve. Spiller (1906) observed preservation of deep sensibility beneath an anesthetic zone of the face after removal of the Gasserian ganglion. Davis (1923) found that cutting the trigeminal root or thoroughly avulsing the Gasserian ganglion in cats led to complete loss of response to superficial stimulation over the corresponding half of the face, the cornea, and the mucous membrane of the nose and mouth; however, definite response to deep stimulation of facial muscles and bones persisted. This deep responsiveness was abolished by section of the facial nerve. Hunt believed corresponding deep facial sensation to be readily demonstrable in human subjects.

Foley and DuBois (1943) studied the position, course, and fiber content of the various functional components of the facial nerve by axon degeneration techniques in 10 cats and 1 dog. Proximal and distal to the geniculate ganglion, he found the sensory and visceral motor axons intimately associated. Between 45% and 62% of the sensory axons join the chorda tympani, 27---40% join the greater superficial petrosal nerves, and a small but consistent minority (11---15%) continue with the trunk of the facial nerve through the stylomastoid foramen and are distributed to the ear with the auricular branch of the vagus.

In examining the muscular branches of the facial nerve, Foley and DuBois (1943) found significant numbers of small axons in addition to the larger somatic motor elements. The sum of these residual fibers, exclusive of the posterior auricular complex, exceeded the number of sensory fibers both in the chorda tympani and in the branches behind the ear. From such axon counts, Foley and DuBois concluded that the axons transmitting deep sensation may be carried by the facial nerve, but have an origin other than the geniculate ganglion, possibly in the facial nucleus of the pons.

Because herpes zoster oticus is a rare disease with good prognosis for survival, there is little neuropathologic material available. This scarcity handicaps precise localization of the facial nerve lesion in the Ramsay Hunt syndrome. Hunt (1937) believed the geniculate ganglion to be inflamed, yet his one autopsied case was atypical in that it lacked vesicles within the auricle (and the geniculate ganglion was not examined). The patient of Maybaum and Druss (1934) had herpetic vesicles on the tympanic membrane and auricle. At autopsy, shrunken and pyknotic geniculate ganglion cells were seen. The cases of Denny-Brown et al. (1944) and Aleksic et al. (1973) have been considered by some to disprove Hunt's hypothesis, since the geniculate ganglion in these cases showed no cellular abnormalities. In the case described by Sachs and House (1956), there was an eruption in the herpes zone of the ear with severe facial palsy, but no sensory loss about the ear. The geniculate ganglion cells appeared normal, yet there was evidence of extensive destruction and regeneration of motor fibers passing through the ganglion.

Blackley et al. (1967) published the findings from a detailed necropsy study of the temporal bone in a case of herpes zoster oticus and showed extensive lymphocytic infiltration of the facial nerve throughout its length. In addition, there was infiltration of the auditory nerve, the chorda tympani, and nerves of the external auditory meatus. The vestibular, spiral, and geniculate ganglia were surrounded by scattered lymphocytes. These investigators stressed that the syndrome bearing James Ramsay Hunt's name is caused by a more extensive lesion of the facial nerve and other nerves and parts of the central nervous system than is implied by the misleading term, ``geniculate ganglionitis.'' Aviel and Marshak (1982) agree with this concept, terming the Ramsay Hunt syndrome a ``cranial polyneuropathy.'' That this is indeed the case can also be inferred from the report by Carroll and Mastaglia (1979) of retrobulbar optic neuropathy and ophthalmoplegia as well as vertigo, deafness, and unsteadiness of gait complicating a case of herpes zoster oticus. In addition, Keane (1975) has reported the case of a 57-year-old man with herpes zoster oticus who developed a delayed fourth nerve palsy followed by a transient abducens nerve palsy about 2 weeks after the onset of ear pain. Geniculate neuralgia has been relieved by section of the nerve of Wrisberg (Wilson, 1950).
 

 

 

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