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Two cases of opercular myoclonic-anarthric status epilepticus Volume 20, issue 3, June 2018

Videos

  • Two cases of opercular myoclonic-anarthric status epilepticus
  • Two cases of opercular myoclonic-anarthric status epilepticus

Figures


  • Figure 1

  • Figure 2

  • Figure 3

  • Figure 4

Opercular myoclonic-anarthric status epilepticus (OMASE) is characterised by fluctuating cortical dysarthria, and even anarthria, associated with epileptic myoclonus involving the glossopharyngeal muscles bilaterally. The condition is considered a form of epilepsia partialis continua in which epileptic activity can originate in either operculum. We present two cases of OMASE.

Case 1

A 78-year-old man attended the emergency department due to difficulty in speaking. Symptom onset was sudden and followed by clonic movements on the left side of his lips. He had a history of high blood pressure and atrial fibrillation and was receiving acenocoumarol, nifedipine, enalapril, and omeprazole. The patient had visited the emergency department two days previously due to difficulty in speaking, however, this episode spontaneously resolved within 15 minutes and was interpreted as a transient ischaemic attack.

During the clinical examination, the patient had a normal level of consciousness and obeyed commands, but was unable to produce sound. Bilateral clonic movements involving the tongue and soft palate resulted in anarthria and severe dysphagia to both solids and liquids. The patient's international normalised ratio was 1.4.

A brain CT scan revealed a small hyperdense area in the right parietal lobe, suggestive of a haemorrhagic lesion. A CT angiogram ruled out occlusion of the major cerebral vessels. The image also revealed an area of increased vascularisation, with prominent vessels in the right fronto-temporal region. This corresponded to an area of increased blood volume and normal transit time on perfusion sequences.

An EEG (figure 1) displayed asymmetric background activity, with slowing in the right fronto-temporal region. No epileptiform activity was detected, despite the fact that pharyngeal clonic movements could be observed throughout the study.

A fibrolaryngoscopy (video sequence 1) showed bilateral, rhythmic, symmetric movements in the soft palate, the base of the tongue, and in both arytenoid cartilages. No abnormalities were observed in the vocal folds.

A brain MRI scan displayed a lesion affecting the insula and adjacent areas of the frontal, anterior parietal, and temporal lobes. The lesion appeared hyperintense on T2-weighted images and showed restricted diffusion, with a gyriform pattern. Two small haemorrhagic lesions were observed on the right parietal lobe. Extensive vasogenic oedema surrounded the lesion, although there was no gadolinium uptake (figure 2). CT venography ruled out venous occlusions.

The patient was started on 500 mg levetiracetam/12 hours. Clonic movements gradually disappeared and the dysarthria and dysphagia resolved.

The lesion was initially interpreted as an area of subacute ischaemia since it appeared to correspond to the territory of the M2 segment of the middle cerebral artery. However, some abnormal features were observed, such as the extensive oedema and increased vascularisation within the region. A CSF analysis and a complete blood count were performed in order to rule out other possible aetiologies.

The blood test returned positive results for anti-nuclear antibodies (titre: 1:640, with a nucleolar pattern). Results for anti-ENA, anti-DNA, and anti-cardiolipin antibodies were negative. Serology results were negative; no neuronal surface antibodies or intracellular antibodies were detected. The study revealed no further remarkable information.

The CSF obtained from the lumbar puncture was clear, with 5 leukocytes/μL, 56 mg/dL proteins, and normal glucose levels. There was no intrathecal immunoglobulin synthesis; the tests for anti-neuronal and onconeural antibodies and the microbiology and serological studies also returned negative results. CSF flow cytometry and cytology results were normal.

The patient was discharged and instructed to continue taking 500 mg levetiracetam/12 hours.

A follow-up MRI scan performed one month after discharge revealed considerable growth of the lesion. The scan revealed contrast uptake and a change in the surrounding oedema, which had become more extensive (figure 2). The perfusion MRI and spectroscopy study results were not suggestive of glial tumour or lymphoma. However, this evidence is not sufficient to rule out these diagnoses. Given the slow progression and the fact that the region initially involved corresponded to a vascular territory, we considered the possibility that the lesion could be secondary to small-vessel vasculitis. However, evidence in support of this hypothesis was insufficient. Unfortunately, the patient was lost to follow-up.

Case 2

A 75-year-old man attended the emergency department due to persistent left hemifacial clonic movements preventing correct speech. No other areas of the body were affected and focal neurological deficits were not observed during the examination. The patient's condition was interpreted as simple partial status epilepticus. He received 1,000 mg levetiracetam intravenously at the emergency department, and the clonic movements resolved. The patient was admitted to hospital.

He had had a generalised tonic seizure three years previously, and had since been receiving 500 mg levetiracetam/12 hours. A brain CT scan performed at the time of that seizure revealed no abnormalities. Two years later, the patient had sustained head trauma with right fronto-temporo-parietal subarachnoid haemorrhage, right fronto-temporal subdural haematoma, and haemorrhagic contusions in the anterior temporal, fronto-basal, and posterior fronto-temporal regions; the patient was treated surgically.

The left hemifacial clonic movements reappeared several hours after admission, extending to the left arm. The patient initially responded to intravenous levetiracetam and clonazepam, but a different pattern of involuntary movements appeared several minutes later. Myoclonus involved the chin and tongue, which protruded continually and arrhythmically from the mouth, accompanied by drooling. The patient presented severe dysarthria and anarthria. His level of consciousness was normal, and he was able to understand and follow orders. The examination revealed no further abnormalities.

It was not possible to obtain an EEG reading until the third day after admission. The results showed epileptiform activity with pseudo-periodic spikes and sharp waves in the right temporal region, and slightly slowed background activity (figure 3).

This EEG activity manifested clinically as continuous movement of the chin (video sequence 2). Further EEG readings were taken on the fifth, ninth, and twelfth days after admission. Despite a degree of progressive improvement, EEG readings continued to show epileptiform activity.

A brain MRI scan displayed the known sequelae of the head trauma. Restricted diffusion, involving the right operculum, was also observed; this is suggestive of postictal changes (figure 4).

At admission, treatment was initiated with 1,000 mg levetiracetam/12 hours. The dose was increased to 1,500 mg/12 hours and lacosamide was added at a maintenance dose of 150 mg/12 hours. As the continuous myoclonic movements persisted, valproic acid was also added at a dose of 2,000 mg/day. Myoclonus progressively improved and disappeared on the seventh day after admission. However, EEG epileptiform activity persisted, and practical anarthria and severe dysphagia remained until post-admission Day 13, when oral nutrition was finally possible.

The patient was diagnosed with OMASE secondary to sequelae of a traumatic brain injury.

Discussion

OMASE is a rare condition, with only five cases registered on the PubMed database: three cases were of vascular origin (Thomas et al., 1995; Bhaskara et al., 2013), one was secondary to autoimmune encephalitis (Zanotelli and Rodrigues, 2013), and one was secondary to a tumour (Thomas et al., 1995). It is a form of simple partial motor status epilepticus that predominantly affects the oropharyngeal musculature. Unlike the more frequently described palatal myoclonus, which generally occurs when brainstem lesions interfere in the dentato-rubro-olivary pathway, OMASE is cortical in origin and responds to AEDs.

OMASE occurs when the opercular region of the inferior Rolandic cortex in either hemisphere is affected by an epileptogenic lesion, which may be of varying aetiology. The anterior operculum contains a large representation of the face in the motor homunculus. The bilateral, symmetric involvement of the facial and oropharyngeal musculature is explained by the bilateral cortical representation of cranial nerves V, VII, IX, X and XII. The presence of exclusively unilateral labial clonic movements is unsurprising, however, as this part of the facial musculature is represented only in the contralateral primary motor cortex.

Anarthria is an epileptic symptom caused by involuntary, myoclonic movements of the muscles involved in speech. However, it may also occur post-seizure in the context of facio-pharyngo-glosso-masticatory paresis, compatible with Todd paralysis. It may be considered a transient form of classic Foix-Chavany-Marie syndrome, also known as anterior opercular syndrome.

Pure anarthria also occurs in epileptic seizures originating in the primary negative motor area (adjacent to the primary motor area) or the supplementary motor area, also known as the secondary motor area. In these cases, the cause of anarthria would be a negative process, and we would not observe the myoclonus shown in the video. Neither would we expect to see the clonic movements of the contralateral hand and face, or dysphagia.

Even if there is clinical suspicion that the epileptic focus is of cortical origin, EEG does not always show epileptiform activity, as we report in Case 1. This may be because the operculum's deep location in the cortex prevents signal detection by surface electrodes.

An EMG would have helped to better characterise muscle activity, but unfortunately, this was not performed in either case.

Early detection of this epileptic phenomenon is important in order to ensure prompt initiation of antiepileptic treatment and prevent the condition from becoming drug resistant. Treatment is the same as that administered for any other type of symptomatic focal epilepsy.

As mentioned previously, the aetiology of the condition varies. In Case 1, diagnosis of a tumour or vasculitic process was proposed, however, this could not be confirmed since the patient was lost to follow-up. In Case 2, the epileptic activity was secondary to a chronic traumatic lesion.

Supplementary data

Summary didactic slides are available on the www.epilepticdisorders.com website.

Acknowledgements and disclosures

The authors acknowledge Esteve Farma for writing support (English translation of the article).

None of the authors have any conflict of interest to declare.