18218ournal ofNeurology, Neurosurgery, and Psychiatry 1995;59:182-184
SHORT REPORT J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.59.2.182 on 1 August 1995. Downloaded from
Palmaris brevis spasm syndrome
Georges Serratrice, Jean-Philippe Azulay, Jacques Serratrice, Jean Pouget
Abstract in the palmaris brevis and abductor digiti Palmaris brevis spasm syndrome is a minimi muscles. The other muscles of the rare and benign condition of localised hand were normal. Motor unit potentials had muscular hyperactivity. In five men, the a normal configuration with 1 mV amplitude, hypothenar eminence underwent sponta- recurrent with 20 to 30 Hz frequency. An neous, irregular, tonic contractions of EMG was normal with voluntary contraction. the palmaris brevis muscle. An EMG Motor and sensory nerve velocities and ulnar showed spontaneous high frequency dis- F wave latency were normal. Carbamazepine charges of normal motor units, without was ineffective. Infiltration of the ulnar nerve evidence of neuropathy or of nerve com- at the wrist with lidocaine reduced the dis- pression. This syndrome resembles other charges but they were not abolished. Finally, restricted muscle hyperactivity syn- there was a dramatic improvement with dromes although there are some differ- phenytoin (200 mg/day). ences. Curiously, the palmaris brevis muscle is not under voluntary control. PATIENT 2 The mechanism of the syndrome could A 37 year old man complained of diffuse be an ephaptic transmission possibly sec- myalgia and exercise intolerance. For eight ondary to the transient and repeated months he had experienced difficulty in writ- stretching of the ulnar nerve superficial ing and had spontaneous, slightly painful, branch. In one patient a root compres- contractions in the right hypothenar emi- sion was the probable origin. nence. Spasms (fig 1) were spontaneous and irregular. Neurological examination was nor- (7 Neurol Neurosurg Psychiatry 1995;59: 182-184) mal and showed no weakness or amyotrophy. There was a diminished vibratory sensation in Keywords: palmaris brevis spasm; continuous muscle the feet. An EMG showed irregular dis-
hyperactivity; myokimia charges of high frequency. Isolated potentials http://jnnp.bmj.com/ were normal in amplitude (0 5 to 1-5 mV), Palmaris brevis spasm is a rare muscular configuration, and duration, in the right pal- hyperactivity syndrome' 2 confined to a rudi- maris brevis and right abductor digiti minimi mentary muscle. The mechanism is unclear. and all the other intrinsic hand muscles were Five patients have been seen in different con- normal. Motor and sensory nerve conduction ditions. velocities and F wave latencies were normal. Results of routine laboratory tests including CSF and lactic acid showed no abnormalities. on September 25, 2021 by guest. Protected copyright. Case reports Magnetic resonance spectroscopy showed a PATIENT 1 delayed phosphocreatine recovery. Quadri- Immediately after surgery (for coxarthrosis, ceps muscle biopsy indicated a moderate type performed four months previously) a 76 year II fibre atrophy without any specific morpho- old man experienced paraesthesiae and logical changes. Baclofen was ineffective. hypoaesthesia in the left little finger and in the internal side of the fourth finger. During PATIENT 3 Cliniques des surgery, the had been on the A 62 year old man had a two Maladies du Systeme patient lying experienced nerveux et de right side and his left arm was fixed in abduc- month history of right C8 root pain and l'Appareil locomoteur, tion by a brace while his hand was dropping paraesthesiae radiating to the right little fin- Hopital de la Timone, loose. Since the operation the patient had ger. He had had a trauma of the neck when 13005 Marseille, France been complaining of spontaneous spasms in aged 40. There were spontaneous contrac- G Serratrice the left hypothenar eminence. Contractions tions and a dimple in the right hypothenar J-P Azulay were irregular without stereotyped duration eminence. There was a weakness of the long J Serratrice J Pouget or frequency. They occurred more often on extensor and flexor muscles of the fingers and Correspondence to: abduction of the left abductor digiti minimi a dorsal interossei amyotrophy. The stretch- Professor G Serratrice. muscle. Results of a neurological examination ing reflex of the right triceps muscle was Received 20 January 1995 were normal. Radiographs of the wrists were absent. An EMG showed high amplitude and in revised form 10 March 1995. normal. An EMG showed bursts of sponta- (8 mV) and frequency potentials in the right Accepted 16 March 1995 neous discharges during two to three seconds abductor digiti minimi muscle as well as in Palmaris brevis spasm syndrome 183
elbow. A cervical myelogram showed right J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.59.2.182 on 1 August 1995. Downloaded from .I. | . | : | C8 compression. . s : s 8 Il : s . s ...... r.-;Xr ... . s . s PATIENT 4 si: ., .: | A 54 year old man complained of a two year :sX .sa IF *: history of paraesthesiae in both little fingers and in both fourth fingers. A year before he had had decompressive surgery of the left ulnar nerve at the elbow without any improvement. He experienced paraesthesiae and spontaneous spasms in both hypothenar eminences. Contractions occurred more often on abduction of the abductor digiti minimi (fig 2). There was hypoaesthesia in both little fingers and in the internal side of both fourth fingers. An EMG showed high amplitude and high frequency potentials in the right (14 mV) and left (16 mV) abductor digiti minimi muscles. Motor nerve conduction velocities and F wave latencies were normal. The amplitude of sensory potentials was slightly decreased in the ulnar nerves. He was treated with phenytoin (200 mg/day) without improvement.
PATIENT 5 A 40 year old man complained of a six month history of spontaneous and irregular contrac- tion in the ulnar side of both hands. Tonic contractions and a dimple in both hypothenar 11g; :#. :' . __ 111 :.:. xj, ;.,d<
1: .t. Ey. of the palmaris aponeurosis. The muscle end- on September 25, 2021 by guest. Protected copyright.
:lw. .> ing is located in the deep derma at the medial :. R .: .2: *;.§. #2. fok side of the hand. Thus the muscle action is to crease and to ripple the skin, giving an
*S x .X hypothenar eminence dimple. Interestingly, .i,¢ ..; the palmaris brevis muscle is not under vol- untary control and its contraction is strictly involuntary. The ulnar nerve divides into superficial and deep terminal branches and the superficial branch extends distally. A small twig supplies the palmaris brevis mus- cle. At the distal border of this muscle the A superficial branch is divided into palmar digi- tal branches for the ulnar side of the little fin- ger and the fourth interdigital space. It is important to note that this ulnar superficial branch has both motor and sensory functions whereas the twig supplying the palmaris bre- vis muscle is a motor nerve only. Theoretically a nerve entrapment causes motor and sensory disturbances. 184 Serratrice, Azulay, Serratrice, Pouget
The symptoms of palmaris brevis muscle ulnar nerve at the wrist resulted in complete J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.59.2.182 on 1 August 1995. Downloaded from spasm are similar in three other reported nerve block abolishing both spasm and spon- patients' 2 and in our five patients but there taneous discharges whereas in patient 1 of are a few differences. The main clinical char- our series, discharges were only reduced by acteristics are (a) frequency in older men; (b) infiltrations. Carbamazepine was ineffective isolated contractions of the palmaris brevis in our patients and baclofen was ineffective in muscle; (c) spontaneous, brisk, irregular tonic patient 2. On the other hand there was a dra- contractions; (d) dimpling in the ulnar side of matic improvement with phenytoin in patient the hand without stereotyped duration or fre- 1 of our series. quency; (e) usually no triggering factors; the The mechanism of the spasm restricted to patient is unable to initiate the contraction at the palmaris brevis muscle is unclear and the will and the contractions start and stop with- aetiology could be different in each of our five out any apparent cause. The voluntary con- patients. In patient 1, the spontaneous dis- traction of the little finger (patient 4) or a charges arose in areas of hypothetical func- pressure on the pisiform (patient 5) could tional focal damage in a stretched peripheral sometimes trigger the dimpling; (J) benign nerve, possibly through ephaptic transmis- evolution for several years; (g) aggravation sion. In patient 2, the exact site of the abnor- under stress or excitement, decrease at rest or mal spontaneous discharges is unknown. during sleep; (h) spasms are either bilateral Abnormalities in membrane channels could (five patients) or unilateral (three patients); create rhythmic generators on the axon. In (z) there is no muscle hyperactivity in the patient 3, a root compression with a probable hypothenar muscles or in any other muscle of double crush at the elbow can be considered the body; (j) sensory disturbances are incon- as a possible mechanism. In the same way sistent. myokimia of the calf associated with Si At rest, EMG shows high frequency dis- radiculopathy is well known.5 In patient 4, a charges of motor units with normal ampli- nerve entrapment of the whole superficial tude, duration, and morphology. Discharges branch of the ulnar nerve could result in occur spontaneously, last a short time, and hypoaesthesia in the distal territory. A nerve recur at irregular intervals. They occur only focal lesion can cause localised myokimia.6 In in the palmaris brevis muscle, except in three patient 5, pressure on the pisiform triggered patients (patient 2 of our series), in whom the the spasm. Thus the site of the abnormal abductor digiti minimi muscle fired occasion- spontaneous discharge varied. ally for brief periods during the spasm. By contrast all other intrinsic hand or arm 1 Satya-Murti S, Layzer RB. Hypothenar dimpling: a muscles were electrically silent during the peripheral equivalent of hemifacial spasm? Arch Neurol spasm. Moreover, voluntary abduction of the 1976;33:706-8. 2 Loron P, Bouche P, Marolle L, Gautier JC. Le spasme ou little finger did not trigger any discharges fossette de l'eminence hypothenar. Rev Neurol (Paris) except in three cases. Motor and sensory 1985;141:149-51. 3 Lapresle J, Fardeau M, Said G. L'hypertrophie muscu- nerve conduction velocities were normal, laire vraie secondaire a une atteinte nerveuse specially in the ulnar nerve, except in patient peripherique. Rev Neurol (Paris) 1973;128: 153-60. 4 Ricker K, Rohkamm R, Moxley RT III. Hypertrophy of 3 of our series in whom a double crush syn- the calf with S, radiculopathy. Arch Neurol 1988;45: drome was probable considering the reduc- 660-4. P. cas 5 Serratrice G, Pellissier JF, Marini JF, Valentin Un http://jnnp.bmj.com/ tion of the motor nerve velocity at the elbow; de sciatique avec hypertrophie du mollet. Rev Neurol F wave latencies were normal. There was no (Paris) 1989;145:474-7. 6 Medina JL, Chokroverty S, Reyes M. Localized myokimia block after proximal motor nerve stimulation. caused by peripheral nerve injury. Arch Neurol 1976; In two patients' 2 lidocaine infiltrations of the 33:587-8. on September 25, 2021 by guest. Protected copyright.