CONCERNING THE MECHANISM OF TRIGEMINAL NEURALGIA AND HEMIFACIAL SPASM*

W. JAMES GARDNER, M.D. Department of Neurological Surgery, The Cleveland Clinic Foundation, Cleveland, Ohio

(Received for publication May 81,196~2)

"Whatever the cause of trigeminal neuralgia the same side and relief of one by alcohol may be, it must be located in the sensory rOOt."--- injection will not affect the other/7 Another WALTER E. DANDY.H important point of similarity is the fact that ESPITE the fact that one is a sensory although each is considered a primary or and the other a motor phenomenon, cryptogenic disease, occasional cases are D trigeminal neuralgia and hemifacial known to occur as a symptom of a tumor, spasm have many features in common: each aneurysnl or arteriovenous anomaly in the occurs in spontaneous paroxysms that re- cerebellopontine angle, 11,12,19,~9,5~ and opera- semble the effect of electrical stimulation of tion invariably has disclosed such a lesion the nerve; each is limited to the distribution when both conditions coexist2 9 of the nerve involved; occurs only in adults, Trigeminal neuralgia differs from hemi- predominantly in women; is subject to re- facial spasm in the following respects: It missions; and although there seldom is de- may occur as a symptom of a tumor ~ or monstrable impairment of function of the aneurysm ~6 in the middle fossa; as a symptom nerve, each has been attributed to pathology of multiple sclerosis, 25,26 Paget's disease and in the nucleus. Each begins in one branch of basilar impression, n,2~ In addition to facial the nerve and tends to spread to all. Both movement, it also is triggered by light touch, types of paroxysms are precipitated by facial is more common on the right side, is helped movements on some occasions but not on by Dilantin/9 and the paroxysms are fol- others. They also occur during sleep. There is lowed by a refractory period/4,as a tendency for the opposite side to become In 50 cooperative patients with typical involved, in which case the attacks are trigeminal neuralgia, Kugelberg and Lind- neither synchronous nor symmetric. In each blom 34 studied this refractory period and also condition, permanent relief can be promised made careful observations regarding the only by total and permanent interruption of stimulus necessary to elicit a paroxysm the nerve. (Fig. 1). One of these patients incidentally All of the above features, so well recog- had platybasia and another an intraeranial nized in trigeminal neuralgia, have been de- aneurysm. They found that spatial summa- scribed in hemifacial spasm by Ehni and tion of the stimulus triggered the pain at a Woltman. 12 In addition, Gardner and Sava 19 lower strength of stimulus and at a shorter showed that the paroxysms of hemifacial latency than if a small area or a single hair spasm, like trigeminal neuralgia, may be were stimulated. In addition to stroking with stopped immediately, and with no impair- the finger, they employed a vibrator con- ment of function, by a nontraumatic manipu- sisting of a round head of a pin attached to lation of the nerve root.. Both trigeminal the menlbrane of a loud speaker. Increasing neuralgia and hemifacial spasm may occur in the frequency or the amplitude of the vibra- the same patient, in which case the par- tions shortened the time of summation. They oxysms, though asynchronous, always are on found that a paroxysm is followed by a re- fractory phase, relative or absolute, the * Presented at meeting of tile ttarvey Cushing duration of which is a function of the dura- Society, Chicago, Illinois, May 1, 196~. tion as well as of the severity of the preceding 947 948 W. JAMES GARDNER

arteriovenous malformation in 3 (~ of whom also had trigeminal neuralgia); by a disloca- tion of the pons attributed to a tumor of the posterior fossa of the opposite side in 1 ; by an anomalous loop of the anterior inferior cerebellar artery in 7; while in only 5 eases did the nerve root appear to be uninvolved. During operation it was observed that paroxysms of hemifacial spasm were pro- dueed by the retraction of the cerebellum and by the slightest touching of the nerve, but with continued gentle manipulation, this response subsided. The operation was fol- lowed by immediate relief of hemifaeial spasm in 1~; by delayed relief in 5; by no re- lief in ~; by demonstrable weakness in 5; and by subsequent recurrence in ~. As a result of these observations, it was concluded that hemifaeial spasm is the ex- pression of a reversible pathophysiologic state commonly produced by mild chronic Fio. 1. Circles denote the circumscribed cutaneous compression of the 7th nerve in the cerebel- trigger zones in 30 patients with trigeminal neuralgia. (Courtesy of Drs. Kugelberg and Lindblom (Fig. 134). lopontine angle; that it results from a trans- axonal "short-circuiting" of the action cur- attack. The refractory period lasts from ~0 rent because of pressure atrophy of the in- seconds to 3 minutes. They concluded that a sulating myelin sheaths; that the associated short-latency jab of pain possibly may be ex- movement or synkinesis which constitutes a plained by simple interaction or short-cir- feature of hemifaeial spasm (similar to that cuiting between touch and pain fibers, but seen in the post-Bell's phenomenon) can be that the lesion responsible for "the trigeminal explained by interaction between efferent neuralgic syndrome" most likely is located in fibers, while the repetitive clonic twitchings the brain stem as was thought also by Crue are compatible with a reverberating circuit and Sutin ~ and by List and Williams2 s They set up between afferent and efferent fibers of found the observations of King et al. n-a3 in muscle. animal experiments difficult to apply to the The results of these operations for hemi- phenomena that they had studied since the facial spasm are comparable to those of potential changes observed in the cat pro- TaarnhOj's operation for trigeminal neu- ceed on a time scale in milliseconds as com- ralgia. In an analysis of ~00 cases of the latter pared to seconds and minutes in the human followed for 3to 6 years Gardner and Miklos'7 subject. found that 6~ per cent had immediate, com- Impressed by the many similarities be- plete and lasting relief of their pain. Con- tween hemifacial spasm and trigeminal trary to the observations of others, 6~ they neuralgia, and since trigenfinal neuralgia is found the incidence of sensory impairment relieved by a nontraumatic manipulation of no higher in the patients with lasting relief the trigeminal rooty we carried out a similar than in those with recurrences. They found procedure on the 7th nerve in 19 cases of that a most effective method of manipulating hemifacial spasm. 19 On exposure of the the nerve root without damaging it was to eerebellopontine angle, the nerve root was spray it with a forceful stream of Ringer's found to be compressed by a cirsoid aneu- solution delivered by a 10 cc. syringe through rysm of the basilar artery in 3 patients; by an a ~l-gauge needle. This method, also em-