Opercular myoclonic-anarthric status epilepticus: A report of two cases.

Opercular myoclonic-anarthric status epilepticus (OMASE) is an uncommon disorder of diverse etiology. This condition is characterized by fluctuating cortical dysarthria associated with epileptic myoclonus involving glossopharyngeal musculature bilaterally. We report two cases of OMASE of vascular etiology in adults. In both patients, ictally clonic expression was consistent with epilepsia partialis continua and bilateral, symmetrical involvement of soft palate in one patient and tongue, lips, chin and inferior jaw in both patients due to bilateral projections of the inferior corticonuclear pathways. The inferior rolandic area of dominant and high frontal region in non-dominant hemispheres were involved by an epileptogenic lesion of vascular etiology, which was confirmed by magnetic resonance imaging of brain and single photon emission computerized tomography. Carotid Doppler study showed thrombosis of internal carotid artery in both patients, suggestive of an embolic origin. Early recognition of OMASE is important for early management of carotid occlusive disease.

Introduction

Paroxysmal lingual myoclonus, often with involvement of the soft palate (epileptic palatal myoclonus), jaw and facial muscles, is an epileptic phenomenon has been described rarely in adulthood.[1234] We report two cases of opercular myoclonic-anarthric status epilepticus (OMASE) of vascular etiology in adults. It was characterized by a fluctuating cortical dysarthria without true aphasia associated with epileptic myoclonus involving soft palatal muscles in one patient and tongue, lips, chin and inferior jaw in both the patients.[3]

Case Reports

Case 1

A 75-year-old, right-handed male patient presented with acute onset of abnormal, involuntary movements of soft palate, tongue, lips and jaw for the last 3 days. He had speech disturbances and swallowing difficulty, occasionally associated with choking episodes. He had no difficulty in voluntary movements of facial, palatal muscles and tongue. There was no history of diabetes mellitus or hypertension. He was a chronic smoker (30 pack years) and occasionally consumed alcohol.

On general physical examination, vital data was normal except for elevated blood pressure (170/100 mmHg). Neurological examination revealed that speech was slow and dysarthric and bilateral, symmetrical, involuntary, continuous, repetitive and synchronized rhythmic myoclonus involving soft palate, lips, chin, tongue and jaw at a rate of 60-80/min [Video 1]; rest of the neurological examination was unremarkable.

Laboratory investigations including hemogram, serum biochemistry and 2D-echocardiogram were normal. Carotid/vertebral arterial Doppler study showed thrombosis of left internal carotid artery. Electroencephalogram (EEG) was normal [Figure 1a]. Magnetic resonance imaging (MRI) of brain, diffusion weighted axial image (DWI) showed restriction in left frontal opercular cortex suggesting an acute infarct [Figure 1b]. Magnetic resonance angiography (MRA) of the brain showed thrombosis of left internal carotid artery.

Figure 1

Normal electroencephalogram (a). Magnetic resonance imaging of brain - diffusion weighted axial image showed restriction in left frontal opercular cortex suggesting acute infarct (b)

He was treated with oral clonazepam (0.5 mg twice daily), gabapentin (100 mg 3 times daily) for palatal myoclonus; oral aspirin (150 mg once daily) and rosuvastatin (5 mg once daily) for ischemic stroke; and oral amlodipine (2.5 mg once daily) for hypertension control. Long-term warfarin therapy was also prescribed. During hospital stay myoclonus improved over a period of 5-7 days [Video 2]. Speech disorder gradually improved in 8-10 days. During the follow-up period of 1 year, the patient had no recurrence of myoclonus.

Case 2

A 72-year-old right-handed female presented with sudden onset of abnormal, involuntary movements of tongue, lips, lower jaw and larynx for the last 2 days. She had speech and swallowing difficulties, occasionally associated with choking episodes. She had no difficulty in voluntary movements of facial, palatal muscles and tongue. She was a known hypertensive for the last 6 years and was on irregular treatment.

On general physical examination, vital data was normal except for elevated blood pressure (180/100 mmHg). Central nervous system examination revealed that speech was slow and dysarthric and bilateral, symmetrical continuous, involuntary, repetitive and synchronized rhythmic myoclonus involving tongue, lips, chin, jaw and larynx at a rate of 90-110/min [Video 3]; rest of the neurological examination was normal.

Laboratory investigations including hemogram, serum biochemistry and 2D-echocardiogram were normal. Carotid/vertebral arterial Doppler study showed thrombosis of right internal carotid artery. EEG was abnormal and revealed diffuse theta slow waves and intermittent bursts of sharp and slow waves over posterior temporal, centro-parietal, occipital regions and occasionally generalized epileptiform discharges [Figure 2a]. Single photon emission computerized tomography (SPECT) showed areas of intense radio-tracer uptake in right frontal region [Figure 2b]. MRI brain-DWI showed restriction in right high frontal region suggesting acute infarct. MRA of brain showed thrombosis of right internal carotid artery.

Figure 2

Electroencephalogram showing diffuse theta slow waves with posterior temporal centroparietal occipital sharp slow waves and occasionally generalized epileptiform discharges (a). Single photon emission computerized tomography showed areas of intense radio - tracer uptake in right high frontal region suggesting ictus focus (b)

She was started on oral clonazepam (0.5 mg twice daily) initially and later sodium valproate (20 mg/kg/body weight) was added. Myoclonic jerks were not controlled in 5 days. Then levetiracetam (20 mg/kg/body weight) and gabapentin (100 mg 3 times daily) were added. Oral amlodipine 5 mg once daily was started for control of hypertension; oral aspirin (150 mg once daily) and rosuvastatin (10 mg once daily) were started for the treatment of ischemic stroke. Long-term warfarin therapy was prescribed. During hospital stay, myoclonus improved over a period of 10-12 days [Video 4]; swallowing difficulties and speech had gradually improved in 14-16 days. During the follow-up period of 2 months, the patient had no recurrence of myoclonus.

Discussion

Epilepsia partialis continua (EPC) is defined as spontaneous, regular or irregular, focal clonic muscular twitches of cerebral cortical origin.[1] It usually continues for hours, days, weeks or months and preferentially involving facial and distal limb muscles but can affect any muscle of the body.[1] Sometimes lingual EPC are observed in Rasmussen's encephalitis.[5]

Sometimes palatal myoclonus is accompanied by synchronous movements of facial muscles, larynx and tongue.[6] This condition is usually caused by a focal brainstem lesion damaging the dentato-rubro-olivary pathway (Guillain Mollaret triangle or myoclonic triangle). Cortical origin epileptic palatal myoclonus can occur in association with simple partial somatomotor seizures or complex partial seizures.[24] In our patients, clinical presentation with “clonic localized muscular twitching repeated at fairly regular short intervals,” involving palatal muscles (cases #1), tongue, lips, chin, lower jaw (both cases) and larynx (case #2), was consistent with EPC.

Because of the relatively large representation of face on the motor homunculus, seizure activity in the contralateral part of the rolandic cortex resulting in clonic seizures involving the face area are common.[7] Unilateral contraction of the angle of the mouth may follow when discharge spreads from the contralateral motor cortex.[8] Otherwise the entire mouth may be involved as it has bilateral cortical representation. In one study,[2] SPECT showed a focal area of increased perfusion in right centro temporal region in a patient with epileptic palatal myoclonus. In another study,[3] imaging in three patients with OMASE showed infarction in right opercular region, left opercular region and oligodendroglioma in right opercular region respectively. In our cases, MRI-DWI showed acute infarct in left frontal opercular cortex in one patient [Figure 2a] and in right high frontal region in the other patient. It was also supported by ictal SPECT findings in the second patient that revealed areas of intense radio-tracer uptake in the right side frontal region suggesting ictus focus [Figure 2b]. These findings are consistent with the aforementioned studies.[23] A strictly unilateral epileptic discharge of frontal opercular or adjacent frontal cortex origin can produce bilateral motor expression because of the bilateral projections of the inferior cortico nuclear pathways. In our patients, the most remarkable feature was almost perfect bilateral symmetry of the myoclonus but with variable clinical expression of glossopharyngeal musculature.

Foix-Chavany-Marie syndrome (FCMS) or anterior opercular syndrome or facio-labio-pharyngo-glosso-masticatory paralysis with automatic-voluntary dissociation or cortical type of pseudobulbar paralysis is a rare cortico-subcortical suprabulbar or pseudobulbar palsy of the lower cranial nerves V, VII, IX, X and XII. The syndrome consists of anarthria, bilateral volitional paresis of the facial, lingual, pharyngeal and masticatory muscles, with preservation of the reflexive, emotional and automatic innervations of the same muscles.[910] This results mostly from bilateral anterior opercular lesion and sometimes unilateral opercular lesion due to cerebrovascular accident.[10] It was not present in both of our cases because they voluntarily move facial, lingual and pharyngeal muscles. Bilateral clonic involvement of face and jaw occurring with true FCMS has been reported.[2]

The EEG was normal in case #1 [Figure 1a]. This could have been because of the fact that surface EEG may sometimes fail to detect paroxysmal activity occurring in deep cortical layers or localized myoclonus.[11] In our case #2, EEG was abnormal in view of diffuse theta slow waves and intermittent bursts of sharp and slow waves over posterior temporal, centro-parietal, occipital region and occasionally generalized epileptiform discharges suggesting pure cortical myoclonus [Figure 2a].

EPC occurring in adults is commonly due to vascular disease and rarely to tumors.[1] Autopsy findings in EPC showed consistent involvement of the motor cortex or closely adjacent areas.[1] Recently magnetoencephalographic analysis in opecular epilepsy showed broadly distributed epileptic foci around the sylvian fissure, including a secondary source, explaining the specific prolonged neurological dysfunction.[12] Similarly, etiological factors in our adult cases include opercular or adjacent frontal region lesions of vascular origin. In both the patients, an embolic stroke involved the inferior rolandic area of the dominant hemisphere [Figure 1b] and high frontal region in non-dominant hemisphere, respectively [Figure 2b]. The source of emboli was thrombus in the carotid network. Evidence from experimental studies suggest that cerebral ischemia can be associated with epileptic seizures as long as the cerebral blood flow does not fall below a critical value as essential metabolites are available for facilitating excessive neuronal activity.[13] Epileptic seizures, mainly partial motor seizures occurred sometime during the clinical course of the disease in 17.3% of carotid patients and in 10.8% of MCA patients.[13] Epilepsy was the presenting symptom in 6.7% of the carotid group patients, whereas no MCA patient had seizures prior to the appearance of a neurological deficit.[13] However, purely hemodynamic mechanisms can also cause repetitive involuntary movements electively precipitated by a given position during acute focal reversible cerebral ischemia.[14]

OMASE is an uncommon disorder of vascular etiology in adults. OMASE occurs when the inferior rolandic area or adjacent frontal cortex is involved by an epileptogenic lesion. Recognition of OMASE is important in the management of carotid occlusive disease because it may indicate development of an acute opercular or adjacent cortical infarction and early intervention leads to complete reversal of this disorder as shown in our case study.

Video 1: This video showing bilateral, symmetrical, involuntary, continuous, repetitive and synchronized rhythmic myoclonus involving soft palate, lips, chin, tongue and jaw at a rate of 60-80/min

Video 2: This post-treatment video shows complete resolution of myoclonus of soft palate, tongue, lips and jaw

Video 3: This video shows bilateral, symmetrical continuous, involuntary, repetitive and synchronized rhythmic myoclonus involving tongue, lips, chin, jaw and larynx at rate 90-110/min

Video 4: This post-treatment video shows complete resolution of myoclonus of tongue, lips, chin, jaw