Journal of Neurology, Neurosurgery, and Psychiatry, 1973, 36, 296-301

Electrophysiological investigations of cephalic tetanus

RICARDO GARCIA-MULLIN AND ROBERT B. DAROFF

From the Department of Neurology, University of Miami School of Medicine,Jackson Memorial Hospital, and the Neurology Service, Veterans Administration Hospital,

Miami, Florida, U.S.A.

SUMMARY Electrophysiological studies of a patient with cephalic tetanus, manifested by trismusand unilateral facial palsy, revealed that the trismus resulted from strictly unilateral masseter spasmwhich stopped during sleep, a normal silent period in the involved masseter muscles, initially pro-

longed distal latency of the paretic orbicularis muscles, and abnormal continuous muscle activity inthe paretic facial muscles which stopped during sleep and after facial nerve block. We conclude thatthe facial paralysis was probably secondary to peripheral nerve dysfunction and the continuousmuscle potentials represented enhanced activity of the nucleus. An intensity spectrum of the inhibi-tory defect in tetanus is postulated.

Cephalic tetanus is defined as a form of thedisease in which trismus is accompanied byparalytic involvement of one or more cranialnerves (Bagratuni, 1952). The tetanus may begeneralized or local, with trismus in the latterconstituting the sole manifestation of spasm. Thecausative injury is usually on the head or faceand the ipsilateral facial nerve is most commonly

affected (Park, 1970). The neurophysiologicalmechanism underlying the cranial nerve palsieshas been an enigmatic feature in a disorderotherwise characterized by spasms secondary toabnormally enhanced motoneuronal activity(Brooks, Curtis, and Eccles, 1957). We areherein reporting a patient with cephalic tetanuswho demonstrated a unique type of constant

FIG. 1 EMG recordingfrom left masseter muscledemonstrating abnormal con-tinuous activity. In A and B,the arrows indicate beginningand end of opening mouthand biting, respectively; bothresulted in an increase in thefrequency and amplitude ofthe muscle action potentials.In C, the jaw jerk (arrow)was followed by a normalsilent period. (Calibration:200 i V and J sec in A andB; 200 ,uV and 50 msecfbr C.)

I296

------------------------ ------------------ ------ -- -----------------------

by copyright. on June 7, 2020 by guest. P

rotectedhttp://jnnp.bm

j.com/

J Neurol N

eurosurg Psychiatry: first published as 10.1136/jnnp.36.2.296 on 1 A

pril 1973. Dow

nloaded from

Electrophysiological investigations of cephalic tetanus

motor unit activity from partially paralysedfacial muscles. Our electrodiagnostic studies inthis patient provide information relevant to thepathophysiology of both the cranial nerve palsyand trismus in tetanus.

CASE REPORT

A 59 year old man fell and lacerated the left side ofhis face eight days before admission to JacksonMemorial Hospital. After the injury, he covered thewound with cloth and did not seek medical attention.Purulent drainage commenced four days later andduring the evening before admission he noted tight-ness of the jaw. On the morning of admission he wasunable to open his mouth and facial asymmetrydeveloped. He never had a complete course of

tetanus immunization but on two separate occasionsafter extremity lacerations, five and two years pre-viously, he received 0 5 ml. tetanus toxoid.Examination on admission revealed an alert,

oriented, cooperative patient with normal vitalsigns. He had an infected wound lateral to the leftorbit which extended from the level of the canthus3 in. onto the forehead. There was no local inflamma-tory process in the pterygoid fossa or temporo-mandibular joint areas. All muscles innervated bythe left facial nerve were partially paralysed resultingin distinct asymmetry of the face. Voluntary effortproduced a trace contraction of the left frontalis andorbicularis oculi muscles and a very weak contractionof the orbicularis oris, but none of the zygomaticus,risorius, or platysma muscles. There were noclinically detectable abnormal movements in any of

FIG. 2 The top EMGtracings in A and B are fromthe right orbicularis oculi andthe bottom tracings from theleft masseter muscle. Stimula-tion of the right supraorbitalnerve in A (arrow) was fol-lowed by normal early andlate reflex responses in theright orbicularis oculi muscle.In B, stimulation of the leftsupraorbital nerve (arrow) wasfollowed by normal late reflexresponse in right orbicularisoculi muscle. (Calibration:100 LV and 20 msec for A;100 ,tuV and J0 msec for B.)In C, the top tracing is fromthe left orbicularis oculi andbottom from the left massetermuscle. Stimulation of leftsupraorbital nerve (arrow)produced no reflex response ineither muscle. In D, top tracingis from left orbicularis orisand bottom from left massetermuscle. Stimulation of leftfacial nerve (arrow) produceda direct motor response in theorbicularis oris which was notfollowed by a silent period.The deflection noted in themasseter represents directmuscle stimulation. (Calibra-tion: 20 ,uV and 10 msec forC; I00 FVand20 msecfor D.)

297by copyright.

on June 7, 2020 by guest. Protected

http://jnnp.bmj.com

/J N

eurol Neurosurg P

sychiatry: first published as 10.1136/jnnp.36.2.296 on 1 April 1973. D

ownloaded from

Ricardo Garcia-Mullin and Robert B. Daroff

the left facial muscles. Trismus was marked and themouth could not be opened more than a 5 mmdistance between upper and lower teeth. Theremainder of the cranial nerve examination revealedno abnormalities.He had normal muscular tone and strength in all

four extremities, with symmetrical tendon jerks andflexor plantar responses. We noted no spontaneousor stimulus-induced extremity muscle spasms andfound no abnormalities on sensory testing. Com-plete blood count, urinalysis, serum electrolytes,total serum protein, calcium, phosphorus, cholesterol,glucose, blood urea nitrogen, serum uric acid,creatinine, bilirubin, LDH, and SGOT were normal.Radiographs of the chest and skull were normal.

Surgical consultants debrided and packed thewound, which was sutured 15 days later with goodhealing. The patient received 2,750 units of humanantitetanus globulin and 1 ml. tetanus toxoid intra-muscularly on admission, a second injection of0-2 ml. toxoid on discharge three weeks later, and

t to

r' 0

j4O.

FP :2

s.to

R I /

0.

F Pl-A-.tAF P

I0

RI

another 0 5 ml. four weeks after discharge. Weinstituted oral diazepam (10 mg every six hours) andintramuscular procaine penicillin (13 million unitsevery six hours) on admission and continued thesedrugs for 17 days.The trismus and facial paralysis improved and

upon discharge 22 days later the distance betweenthe teeth upon opening the mouth was 12 mm.Taste, which could not be examined previouslybecause of trismus, was now normal on both sides.The trismus completely disappeared eight weeksafter admission but the left facial paresis waspresent, although minimally, at 10 weeks.

ELECTROPHYSIOLOGICAL STUDIES We used bipolarneedle electrodes (Disa 901 3K0801 and 9013K0802),a Disa 3 channel electromyograph, and a Tektronix565 oscilloscope for electromyography (EMG). Forstimulation of the facial and supraorbital nerves weused a disc surface electrode 9 mm in diameter taped

FIG. 3 Simultaneous EEGand EMG recordings from leftmasseter (top) and leftorbicularis oris muscles(bottom). There was abnormalcontinuous activity in bothmuscles at rest while subjectwas awake in A, and afterarousal in C. There was com-plete cessation of all muscleactivity during light sleep in B.(Calibration: 50 V. V and I secfor the EEG; 50 Vand 100msec for the EMG.)

298

by copyright. on June 7, 2020 by guest. P

rotectedhttp://jnnp.bm

j.com/

J Neurol N

eurosurg Psychiatry: first published as 10.1136/jnnp.36.2.296 on 1 A

pril 1973. Dow

nloaded from

Electrophysiological investigations of cephalic tetanus

to the skin with a silver plate 4 cm x 3 cm over thesternum as the indifferent electrode. Square pulses of0 1 to 0 5 msec duration and voltages from 50 to500 V were delivered with a Disa Multistim stimu-lator.

1. There was abnormal EMG activity in the leftmasseter muscle at rest which consisted of bi- ortriphasic muscle action potentials with amplitudesranging from 50 to 800 ,uV, and durations from 3 to6 msec, firing at frequencies between 12 and 20 persecond. There was no tendency for this activity tobecome grouped in doublets or multiplets, and itpersisted unchanged in amplitude and frequencyduring continuous recordings for periods of up to30 minutes. Voluntary biting as well as effort toopen the mouth produced an increase in the fre-quency and amplitude of the muscle action poten-tials (Fig. 1, A and B). Tapping of the jaw elicited areflex jerk with a synchronous increase in the num-ber of muscle action potentials which was followedby a silent period lasting 75 msec (Fig. IC). Stimula-tion of the supraorbital and/or facial nerves oneither side failed to change the pattern of muscleaction potential activity in this left masseter muscle(Fig. 2). The activity disappeared completely duringsleep (Fig. 3).

In follow-up studies performed two and six weekslater, the EMG activity of the left masseter persisted,although decreasing in the number, amplitude, andfrequency of units. Fifteen days after the initialexamination only one or two motor units fired at

frequencies of 12 to 16 per second with amplitudesaround 250 V±V; there were transient periods of totalsilence lasting a few seconds. At 10 weeks afteradmission, no abnormal activity was recorded fromthis muscle.

2. The right masseter muscle was silent at rest,and biting produced a normal interference pattern.No activity was present during effort to open themouth.

3. We recorded abnormal activity in the leftorbicularis oris and orbicularis oculi muscles whichconsisted of biphasic and triphasic muscle actionpotentials with amplitudes from 100 to 250 ,uV, anddurations between 2 and 4 msec, firing at frequenciesfrom 30 to 40 per second (Fig. 4). This EMG activitypersisted unchanged in amplitude or frequencyduring prolonged periods of observation up to onehour. Voluntary contraction increased the frequencyand amplitude of the muscle action potentials but nopolyphasic potentials of prolonged duration werefound. No reflex response was noted in these musclesafter left supraorbital nerve stimulation (Fig. 2C) andno silent period ofthisEMG activityfollowed stimula-tion of the left facial nerve (Fig. 2D). However, bothlight sleep (Fig. 3) and lidocaine infiltration of thecervicofacial division of the left facial nerve (Fig. 5)completely abolished the spontaneous activity in theleft orbicularis muscles. We found no decrement orincrement in the activity of the left orbicularis oculimuscle recorded with surface electrodes when trainsof supramaximal stimuli of 2 sec duration and fre-

FIG. 4 A and B demon-strate the abnormal con-tinuous EMG activity atdifferent sweep speeds fromthe orbicularis oris muscle atrest. In C, the muscle poten-tials increased in amplitudeandfrequency duringattempts at voluntary con-traction (whistling). (Calibra-tion: 100 FiV and 1 sec in A;100 ,uV and 100 msec in B,500 V and I sec in C.)In D, the EMG recordings of

MSSMINm the left orbicularis oculi- _ muscle during five successive

sweeps demonstrated the_ continuous muscle activity.

The high frequency, persist-ence, and regularity of thisactivity did not resemblefibrillations. (Calibration:20 ,uV and 100 msec.)

299by copyright.

on June 7, 2020 by guest. Protected

http://jnnp.bmj.com

/J N

eurol Neurosurg P

sychiatry: first published as 10.1136/jnnp.36.2.296 on 1 April 1973. D

ownloaded from

Ricardo Garcia-Mullin and Robert B. Daroff

quencies of 3, 10, and 30 per second were deliveredto the left facial nerve.

Follow-up studies six weeks after admission re-vealed that the frequency of the spontaneous activityin the left orbicularis muscles had decreased tolevels between 25 and 30 per second.

Distal motor latency at the left orbicularis oculimuscle after stimulation of the left facial nerve at theangle of the jaw was 6 msec on admission, 5 msec attwo weeks, and 3-2 msec at six weeks.

4. We found no abnormal activity in the rightorbicularis oris or oculi muscles. There were normalinterference patterns on voluntary contraction;

FIG. 5. EMG recording from left orbicularis orismuscle before (A) and after (B) infiltration of thecervicofacial division of the left facial nerve with2 ml. 1J% lidocaine. Arrow indicates supramaximalstimulation of the left facial nerve proximal to thearea ofblock. In B, there was complete disappearanceofspontaneous activity and markedly reduced responseto nerve stimulation after lidocaine block. (Calibra-tion: 50 uV and 20 msec.)

normal early and late responses following stimula-tion of the right supraorbital nerve; and normal lateresponses following stimulation of the left supra-orbital nerve (Fig. 2, A and B).

DISCUSSION

Tetanus toxin produces muscle spasms byblocking the postsynaptic inhibition of moto-neurones by interneurones (Brooks, et al., 1957);in spinal interneurones the toxin reduces theamount of glycine released from inhibitoryterminals (Curtis and de Groat, 1968). Theclinical expressivity of the effects of tetanus toxinon the nervous system ranges from severe general-ized involvement to milder forms of localizedspasms (Struppler, Struppler, and Adams, 1963)such as were manifested in our patient. Ourelectrodiagnostic findings indicate a similarintensity spectrum of the inhibitory defect basicto the disorder. Struppler et al. (1963) reportedthe absence of a silent period in the massetermuscles after the jaw jerk as characteristic oftetanic trismus; however, our patient withtrismus had a normal silent period. Similarly,whereas trismus and extremity muscle spasmshave been observed clinically to persist duringsleep, we demonstrated the total absence ofmasticatory and facial muscle activity duringsleep. Thus, the inhibitory defect in at least localtetanus need not be as intense as that usuallyassociated with generalized and severe forms ofthe disorder. We suspect that, if left untreated,the tetanus may have evolved into a generalizedtype with the usual electrophysiological evidenceof profound loss of inhibition.The abnormal muscle action potential activity

recorded in the partially paralysed facial musclesof the patient has not, to our knowledge, beenreported previously. He did not have theclinical manifestations of facial hemispasmwhich occasionally occurs in cephalic tetanus(Watkins, 1939), and the electromyographicpattern was inconsistent with hemispasm (Bratz-lavsky and Vander Eecken, 1971). The con-tinuous activity should also be differentiatedfrom the facial myokymia found in cases ofmultiple sclerosis and brain-stem gliomas, wherethe firing pattern is more bizarre and complexwith a tendency to grouping of muscle actionpotentials into multiplets (Matthews, 1966).

300

by copyright. on June 7, 2020 by guest. P

rotectedhttp://jnnp.bm

j.com/

J Neurol N

eurosurg Psychiatry: first published as 10.1136/jnnp.36.2.296 on 1 A

pril 1973. Dow

nloaded from

Electrophysiological investigations of cephalic tetanus

The absence of a silent period in the con-tinuously active left orbicularis oculi muscleafter left facial nerve stimulation is not specificfor tetanus but may occur in cases of facialmyokymia (Garcia-Mullin, unpublished observa-tions).The cranial nerve palsies in cephalic tetanus

could share the same mechanism as the motorparalysis of extremities that occasionally occursin severe generalized tetanus. Kaeser and col-leagues (1968, 1970) regarded the latter assecondary to a block in neuromuscular trans-mission possibly due to impaired release ofacetylcholine. Watkins (1939) considered thefacial paralysis of cephalic tetanus as a peripherallesion on the basis of associated ipsilateral tasteloss in his patient. Park (1970) and others, how-ever, postulated nuclear dysfunction. We foundno abnormal decrement or increment in theevoked facial muscle potentials after trains ofdifferent frequency stimuli delivered to thefacial nerves. This mitigated against a causativedefect in neuromuscular transmission. The pro-longed distal latency of orbicularis contractionearly in the course of the illness, which improvedafter treatment, probably indicates the site ofparalysis to be along the peripheral course of theVII nerve (Gilliatt and Taylor, 1959; Taverner,1965), but may also be compatible with dys-function affecting predominantly the largermotoneurones of the VII nerve nucleus.

Lidocaine block of the facial nerve eliminatedthe abnormal continuous action potentialsrecorded in the paralysed orbicularis muscleinnervated by that nerve. This indicated that theorigin of the muscular activity was proximal tothe block. The cessation of these potentials duringsleep implicates a causative central or nuclearabnormality. We suggest that neurones withinthe left facial nucleus, presumably released from

inhibitory control, fired continuously and re-sulted in the recorded abnormal resting activityin the muscles. We are unaware of electromyo-graphic studies of the facial muscles in risussardonicus, but suspect that this condition mayrepresent an advanced manifestation of ab-normal release of facial motoneurones. Perhapsthe coexisting peripheral facial paralysis maskedthe clinical appearance of risus sardonicus in ourpatient.Our study also demonstrated that clinically

distinct tetanic trismus may result from strictlyunilateral masticatory muscle spasm.

REFERENCES

Bagratuni, L. (1952). Cephalic tetanus with report of a case.British Medical Journal, 1, 461-463.

Bratzlavsky, M., and Eecken, H. Vander (1971). Hemispasmefacial primitif: correlations cliniques et electromyo-graphiques. Acta Neurologica Belgica, 71, 365-382.

Brooks, V. B., Curtis, D. R., and Eccles, J. C. (1957). Theaction of tetanus toxin on the inhibition of motoneurones.Journal of Physiology, 135, 655-672.

Curtis, D. R., and de Groat, W. C. (1968). Tetanus toxin andspinal inhibition. Brain Research, 10, 208-212.

Gilliatt, R. W., and Taylor, J. C. (1959). Electrical changesfollowing section of the facial nerve. Proceedings of theRoyal Society of Medicine, 52, 1080-1083.

Kaeser, H. E., Muller, H. R., and Friedrich, B. (1968). Thenature of tetraplegia in infectious tetanus. EuropeanNeurology, 1, 17-27.

Kaeser, H. E., and Saner, A. (1970). The effect of tetanustoxin on neuromuscular transmission. European Neurology,3, 193-205.

Matthews, W. B. (1966). Facial myokymia. Journal ofNeurology, Neurosurgery, and Psychiatry, 29, 35-39.

Park, D. M. (1970). Cranial nerve palsies in tetanus: cephalictetanus. Journal ofNeurology, Neurosurgery, andPsychiatry,33, 212-215.

Struppler, A., Struppler, E., and Adams, R. D. (1963). Localtetanus in man. Its clinical and neurophysiological charac-teristics. Archives of Neurology, 8, 162-178.

Taverner, D. (1965). Electrodiagnosis in facial palsy. Archivesof Otolaryngology, 81, 470-477.

Watkins, A. L. (1939). Facial paralysis in cephalic tetanus.Archives of Neurology and Psychiatry (Chicago), 41,788-792.

301

by copyright. on June 7, 2020 by guest. P

rotectedhttp://jnnp.bm

j.com/

J Neurol N

eurosurg Psychiatry: first published as 10.1136/jnnp.36.2.296 on 1 A

pril 1973. Dow

nloaded from