Persistent facial myokymia: a rare pathognomic physical sign of intrinsic brain-stem lesions: report of 2 cases and review of literature.RR Sharma, NV Mathad, DN Joshi, TB Mazarelo, MM Vaidya
Dept. of Neurosurgery, Seth G.S. Medical College, Bombay, Maharashtra.
Characteristically continuous facial myokymia is a pathognomonic, exceedingly rare physical sign of intrinsic brain-stem lesions e.g. multiple sclerosis (where the myokymia lasts only for a few months), pontine glioma (where it is unremitting for years). The physiopathogenesis is unclear. Electromyographic patterns are characteristic. Therapy and prognosis are related to the basic aetio-pathological process. Only two out of 132 cases of intrinsic brain-stem lesions in the department of Neurosurgery, Seth G.s. Medical College, Bombay over a period of 3 decades, exemplify its rarity. These two cases are reported here and the relevant literature is reviewed.
Keywords: Adult, Brain Neoplasms, physiopathology,radiotherapy,Brain Stem, physiopathology,Case Report, Cranial Irradiation, Electromyography, Evoked Potentials, Auditory, Brain Stem, physiology,Facial Muscles, innervation,Fasciculation, physiopathology,Female, Glioma, physiopathology,radiotherapy,Human, Male, Tomography, X-Ray Computed,
Facial myokymia is characterised by spontaneous, continuous, firne, involuntary undulating waves (ripples) of spreading muscle contraction across one side of the face, 'like a parallel moving army of cutaneous earthworms'. It is a rare and curious sign of intrinsic brainstem lesions of heterogenous etiology e.g. multiple sclerosis or pontine glioma. Pontine glioma is not an unusal condition but continuous facial myokymia as a presenting feature is rate. It was reported in only two out of all cases of posterior fossa tumours operated upon over a16 year period at AIIMS, New Delhi. Of a total 132 brainstem lesions seen in the Department over the past 30 years only two patients manifested facial myokymia. We report these two cases and present review of the relevant literature.
Case No. 1:
A 22 year old male (NS No. 136/85) admitted with two and half year history of fine, progressive continuous; involuntary movements (ripples) confined initially to left lower eye lid but later speread all over the left hemi-face, from forehead to chin in a couple of weeks. These ripples, uninfluenced by rest, sleep or voluntary actions, were more prominent in lower lid and cheek. Progressively palperbral fissure too got narrowed. On enquiry he gave 8 year history of epiosodic bilateral tinnitus and 6 month history of paraesthesia over left hemiface and in all four limbs. Interrogation yielded no history of significant past illness. On clinical examination no abnormality outside the nervous system noted. Neurological examination revealed bilateral first degree horizontal jerky nystagmus, hypesthesia in mandibular nerve distribution bilaterally, typical facial myokymic movements on left side - fine, rhythmic, continuous, undulating wave-like (ripples) involuntary movements being more pronounced in left lower lid, ipsilateral spastic paretic facial muscle (left side), negative Rinne's test on left side, generalized hyperreflexia in limbs, upgoing left plantar response and mild cerebellar signs in left limbs.
Laboratory studies were unremarkable. Computed tomogtraphic scan (C.T.Scan) of brain (See [Figure:1]) showed the expansion of pons due to a ill-defined, diffuse, non-enhancing hypodense mass lesion extending in the left middle cerebellar peduncle too, and deforming displacing the f6urth ventricle posteriorly and to the right and obliterating left cerebellopontine angle. Brainstern auditory evoked response (BAER) was normal on right side. On the left side only wave-I was present at normal latency (2.0 msec) whereas rest of the normally occurring waveforms (II-V) were absent. The consensual R2- response of the left blink reflex was abnormally prolonged. Electromyographic (EMG) study of left orbicularis oris at rest has recorded continuous spontaneous potentials indistinguishable from those of 'normal motor unit potentials on activity'. On submaximal voluntary effort, the normal motor unit potentials and on maximal voluntary effort, a complete recruitment pattern were obtained with a diagnosis of Contine glioma, patient was given radiothereapy (Co-60 photons: 5000 rads) following which he had transient decrease in the intensity of facial myokyrnic movements. Appearance of the pontine glioma on the repeat CT scan done about one and half year later showed no change than that seen on the previous one. We are following this patient's progress in our outpatient department.
Case No .2:
A 35 year old female (NS No. 393/86) presented with fine, progressive, continuous involuntary movements, weakness and paraesthesinumbness confined to the right half of the fave (involuntary movements were more marked in right lower lid and cheek) since six months. For the same duration she also had deafness in right ear and hoarseness of voice. Nasal regurgitation and imbalance whilst walking have developed since six weeks. Mild generalized headaches and diplopia appeared in last 4 weeks. The involuntary facial movements caused a severe cosmetic problem and were not influenced by rest, sleep or voluntary actions. No other significant, past history of any illness noted.
Clinical examination revealed no abnormality outside the nervous system. The involuntary movements over the entire right half of the face was observed to be fine, continuous, undulating wave- like (ripples) spereading muscle contractions (more marked in the lower lid and cheek). The right palpebral fissure was narrow and the right angle of the mouth was ipsilaterally drawn. Signs of multiple cranial nerve impairment on the right side were noted; abducens, motor division of trigeminal nerve (deviation of jaw to the ritgt on opening the mouth), auditory nerve (negative Rinne's test), facial nerve (spastic- paretic facial muscle paresis) and accessory nerve (torticollis). Hypertonia in left limbs and gross appendicular and trunkal ataxia noted.
Routine haematological, metabolic and radiological (skull) studies were unremarkable. CT scan of brain (See [Figure:2A]) showed a diffuse, low attenuation, non-enhancing extensive mass lesion within the brain stem (medulla-pons-midbrain), which squashed and posteriorly displaced the fourth ventricle and obliterated the pre-pontine and cerebellopontine cisterns and also caused mild dilation of the lateral ventricles. BAER was normal on the left side. On the right side, only wave-1 was present at normal latency (1’36 msec), and the other normally occurring waveforms (ii to v) were absent (See [Figure:2B]). EMG study of right orbicularis oris at rest has recorded continuous spontaneous potentials indistinguishable from that of normal motor unit potentials at maximal activity (See [Figure:2C]). With the diagnosis of extensive brainstem glioma, patient was given radiotherapy (Co60 Photons: 4000 rads to whole brain and 2000 rads to brainstem using a reduced field). Fourteen months following radiotherapy, repeat CT scan of brain (See [Figure:2D]) showed appreciable reduction in the size of the brainstem tumour and its effect on the surrounding structures including fourth ventricle however patient has persistent facial myckymic movements on the right side. We are periodically following her progress in our outpatient department.
A patient with facial myokyrnia usually complains of a continuousloersistent ripplincl of the muscles of the lower lid and cheek on one side (although sometimes the entire hemiface, frontalis to platysma, may be involved) and a stiff and swollen sensation.
It is not an incapacitating symptom but is certainly distressing and alarming due to the cosmetic effect (as seen in our case no. 2). Continuous facial myokymid occurs with no predilection to age, sex or race. The onset is usually abrupt but the intensity and natural history depend upon the underlying pathological process. Sleep, rest and volitional activities have no effect on myokyrnic movements. In long-standing cases, persistent narrowing of affected palperbral fissure and ipsilateral drawing of affected angle of mouth result ('spastic- paretic facial muscle contracture') as noted in both our cases. In 1895, Schultze  introduced the term 'myokymia' (Greek: mys-muscle and kyrnia wave) as lmuskelwogen' in the description of generalised wide spread continuous wave like twitchings, more pronounced in the calves of an young patient and considered it to be the manifestation of benign neuromuscular irritability. Since than, generalised wide spread myokyrnic movements have been reported in association with lead poisoning, thyrotoxicosis, scleroderma, systemic infections, intoxications, intrinsic spinal cord lesions, myotonia, rest-leg syndrome, peripheral neuropathy, polyradiculopathy etc,.
Benign myokyrnic movements in facial muscles may be encountered occasionally after strenuous athletic avitivity, strain, fatigue, in normal persons and are without any pathological significance. Oppenheim, coined the term 'facial myokymia' and considered it to be an early sign of an involvement of the brainstem in multiple sclerosis. This has been confrmed by other workers,. Various causes other than multiple sclerosis are also reported sporadically e.g poliomyelitis, suicidal hangings, post-Bell's palsy or poly radiculopath-. In these aforementioned conditons (including multiple sclerosis) facial myokymia is usually transient lasting from two weeks to six months.
Persistent facial myokymia, continuing unremittingly until death, is found in intrinsic malignant mass lesions of the brainstem e.g. pontine glioma (commonest cause),,,,,,,, pontine metastases (less frequent cause), cerebelier glioma infiltrating the pons and exophyting in the cerebellopontine angle (rare cause In 3:1 benign lesions such as pontine tuberculoma  and acoustic neuroma (severely compressing the brainstem), facial myokymia has been reported to be relieved following appropriate therapy. Interestgly Radü et al described facial myokyrnia associated with an epidermoid tumour involving the fundus of internal auditory canal the labyrinth and middle ear cavity (where it would be related to the facial nerve rather than brainstem). In another case they found at autopsy no contact between the posterior fossa tumour and the brainstem.
The basic physic-pathogenic mechanism responsible for facial myokymia is still unknow. However hyperxcitability of facial moto-neurones due to supranuclear (by interruption of corticonuclear pathways descending upon the facial nucleus: disinhibition),,, nuclear (direct excitation by demyelinating plaque or glioma, setting up the steady depolarising state affecting the soma-dendritic membranes of facial moto-neurones),, perinuclear (deafferentation: facial motoneurones are isolated from the adjacent internuncial pool mediating sensory input by oedema or by pressure), mechansisms have been suggested. Hyperexcitability of the intraaxial portion of the facial nerve in the pontine lesions, and of the extraaxial portion of the facial nerve in extrinsic lesions has also been suggested as possible mechanisms,,.
Facial myokymia may be differentiated from hemifacial spasm, facial tics and palatal nystagmus by its characteristic clinical features and electromyographic patterns,,.
Clinical neurophysiological tests and computed tomogtaphic scan (C7 scan) of the brain are the important diagnostic procedures. Two types of electromyographic patterns (continuous and discontinuous) characterise facial myokymia. In the continuous type, single, double or group (bursts) rhythmic discharges recur with striking regularity at the rate of 0.8 to 30 cps (or at intervals of 100 to 200 ms); this type was present in the two cases reported here. In the discontinuous type, the bursts of motor activity at 30 to 40 impulses per second last for 100-900 ms and repeat at regular intervals of 100 ms to 10 seconds with a brief period of quiescence in between the activities. Brainstem auditory evoked responses characteristically show evidence of retro-cochlear lesions (as was found in our patients). CT scan of brain shows typical enlargement of brainstem (due to an intrinsic lesion such as glioma) resulting in obliteration of prepontine and cerebellopontine cisterns as well as compression and displacement of the fourth ventricle. The therapy and the prognosis depend on the nature of basic pathological process. Biopsy and /or radiotherapy are indicated for pontine glioma. The facial myokyrnia persists unremittingly until death in these patients.
With the reported 2 cases, we confirm that persistent unremitting facial myokymia is a rare (1.5 percent cases of intrinsic brainstem lesions in our series) and 'pathognomonic sign' and a clue to the diagnosis of intrinsic brainstem lesions - usually pontine glioma. Since multiple sclerosis is a rare condition in our country, the presence of persistent facial myokymia should direct our suspicion to pontine glioma until unless proved otherwise.
We thank Dean, Seth GS Medical College and King Edward Memorial Hospital, Mumbai, for permitting us to use hospital records and Dr. P Wadia (Jaslok Hospital, Mumbai) and Dr. SS Pandya (Mumbai Hospital, Mumbai) for electrophysiolgical studies and Mr. U.M. Godhwani for excellent secretairal help.