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| Year : 1999 | Volume
: 47
| Issue : 3 | Page : 241-2 |
Facial myokymia as the presenting symptom of a pontine glioma.
Selvapandian S, Rajshekhar V
Department of Neurological Sciences, Christain Medical College and Hospital, Vellore, Tamil Nadu, 632004, India.
Correspondence Address:
Department of Neurological Sciences, Christain Medical College and Hospital, Vellore, Tamil Nadu, 632004, India.
How to cite this article:
Selvapandian S, Rajshekhar V. Facial myokymia as the presenting symptom of a pontine glioma. Neurol India 1999;47:241 |
Facial myokymia (FM) is a rare form of involuntary movement affecting the facial muscles. It is clinically defined as continuous twitching of small bands or strips of muscles that give an undulating or rippling appearance to overlying skin, descriptively called as `bag of worms' appearance. It was first described by Bernhardt in 1902. Initially thought to be characteristic of multiple sclerosis, it was later observed with neoplastic and inflammatory lesions of the brainstem. In long standing cases there in narrowing of palpebral fissure and persistent drawing of angle of mouth called `spastic paretic facial contracture' (SPFC). In this report we describe a case where FM and SPFC were the presenting symptoms of a pontine glioma and emphasize the need to consider an intrinsic brainstem mass in any patient presenting with FM.
A 41 year old man presented with history of twitching of right side of the face for the last 2 years. The twitching started in the cheek and spread to involve the whole right side of the face. He noticed progressive narrowing of the palpebral fissure and deviation of the angle of the mouth to the left side. He also noticed impaired hearing on the right side for one year and loss of balance on walking with a tendency to sway to the left. There were no features suggestive of raised intracranial pressure or any other neurological deficits.
On examination his fundi were normal. He had bilateral, horizontal, gaze evoked, coarse, jerky nystagmus more on looking to the left. He had facial myokymia on the right side with facial paresis and contracture. Taste on both sides of the tongue was intact. He also had sensori-neural deafness on the right side and mild left cerebellar dysfunction. CT scan done a year ago was reported as normal, however retrospectively the right side of the pons appeared minimally enlarged. He had a recent MRI which showed a diffuse iso/hypointense mass on the right side of the pons in T1W images. On T2W images the mass was hyperintense and seemed to extend to the right cerebellar peduncle [Figure 1]. Facial EMG was characteristic of facial myokymia. The mass was biopsied stereotactically through a right frontal twist drill craniostomy under local anesthesia. It was reported as astrocytoma grade I. He was advised radiotherapy. After radiotherapy the spastic facial contracture resolved to some extent, his right eye opened up while the myokymia persisted. The gait ataxia improved.
Initial reports describing FM often confused it with hemifacial spasm and spastic paretic facial contracture.[1] Later it was realised that FM is a specific entity with its own characteristic features. FM in its pure form is seen in multiple sclerosis, early in its course and it is usually self limited.[1],[2],[3] In multiple sclerosis it is not associated with SPFC or facial palsy.[1],[2],[3] When FM is caused by an intrinsic brainstem mass SPFC and facial paresis are usually associated with it.[4],[5],[6],[7] Brainstem tuberculoma,[5] metastatic disease of the Brainstem,[2] and other posterior fossa masses[2],[8] have been reported as a cause of FM.
Autopsy studies have shown that lesions causing FM were often rostral to the facial nerve nucleus and the nucleus was relatively well preserved. It was postulated that the interruption of supranuclear control led to a release phenomenon or reverberating circuit within the facial nucleus leading to FM.[2],[6],[7],[8],[9],[10] However FM has been observed in patients with Guillain-Barre syndrome.[8],[9] where it is usually bilateral, and during recovery from Bell's palsy.[9] In these instances peripheral mechanisms such as focal demyelination leading to `cross talk' have been postulated to be the cause of FM. Similarly FM associated with exophytic brainstem masses[11] is supposedly caused by compression of the nerves in the cerebellopontine angle. The mechanism is akin to that proposed for neuralgias, caused by vascular compression of the cranial nerves.
Medullary syrinx with FM[2],[9] has been described. The authors proposed interruption of aberrant cortico-bulbar fibres (Dejerine's tract) causing supranuclear denervation of the facial nerve nucleus as the mechanism for FM. Another recent report suggests that compression due to either the mass or oedema caused a change in `microenvironment' in the facial nerve nucleus and led to its hyperactive state.[7] Due to the association of FM with different pathologies at different locations it appears as though the pathogenesis is multifactorial. Though FM associated with multiple sclerosis is usually self limiting, when associated with intrinsic brain stem masses it is seen to be unrelenting and progressive. However in two recent reports[7],[11] it has been observed that surgical decompression of the tumour led to temporary resolution of the myokymia.
Surprisingly FM has not been reported in children even though pontine gliomas occur most frequently in the pediatric age group.[11],[12] FM was not seen in any of our 76 pediatric patients with brainstem gliomas and this was the first case among 34 adult brainstem gliomas treated at our center. The diagnosis of a brainstem glioma was delayed in our case as only a CT scan was done initially. Had an MRI been done at initial presentation, it is possible that the tumour would have been diagnosed earlier. This emphasises the need to suspect an intrinsic brainstem mass in a patient with FM. Close follow up with imaging, preferably MR, should be performed if initial imaging studies do not reveal the brainstem pathology.
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