|Year : 2016 | Volume
| Issue : 3 | Page : 142-144
Paroxysmal dystonia masquerading as focal onset seizure in patient with multiple sclerosis
Azra Zafar, Alaa Mohsin Almajid
Department of Neurology, King Fahd Hospital of the University, Khobar, Saudi Arabia
|Date of Web Publication||14-Dec-2016|
Department of Neurology, King Fahd Hospital of the University, P. O. Box 2208, Khobar 31952
Source of Support: None, Conflict of Interest: None
Paroxysmal movement disorders are clearly known to be associated with multiple sclerosis (MS). Paroxysmal dystonia (PD), also known as tonic spasm, is a well-recognized feature of MS. These symptoms as an initial presenting feature may be a diagnostic challenge for the treating physician and can often be mistaken as focal onset seizures. We present a case of 26-year-old girl, who presented with recurrent brief attacks of abnormal involuntary movements affecting the right upper extremity and neck for 3 years. She was diagnosed as a case of focal onset seizure disorder and was started on valproic acid. Her symptoms did not improve at all. She was admitted at King Fahd Hospital of the University, Khobar, Saudi Arabia and was diagnosed as a case of PD secondary to MS. Carbamazepine was started and showed promising results.
Keywords: Dystonia, movement disorder, multiple sclerosis
|How to cite this article:|
Zafar A, Almajid AM. Paroxysmal dystonia masquerading as focal onset seizure in patient with multiple sclerosis. Saudi J Health Sci 2016;5:142-4
| Introduction|| |
Paroxysmal movement disorders although not commonly recognized but are clearly known to be associated with multiple sclerosis (MS). Paroxysmal dystonia (PD), also known as tonic spasm whether painful (painful tonic spasm [PTS]) or not, is a well-recognized feature of MS. These symptoms can often be misdiagnosed as seizure disorders and can be the reason for delay in starting appropriate therapy.
| Case Report|| |
A 26-year-old girl with no known comorbid and insignificant past and family history presented with 3 years history of repeated attacks of involuntary, painful movements affecting the right upper and lower extremities leading to abnormal posturing lasting for few seconds. Initially, the frequency was few attacks per month which later on increased to many times per day. These attacks were not associated with alteration of conscious level, auditory or visual hallucination, up rolling of the eyes, tongue biting, or sphincter incontinence. These attacks were aggravated by physical movements and mental stress. The patient visited to the emergency department of nearby hospital many times with these complaints and was given parenteral diazepam and later on started on valproic acid.
On further inquiry, the patient was found to have two attacks of quadriparesis few months apart 2 years ago, which improved completely within few days without any specific treatment. She also had complaint of weakness of the right side of body for 3 months associated with difficulty in walking. However, as the patient was having frequent attacks of abnormal movements, she was correlating the weakness to these episodes.
On examination, she had normal vitals and higher mental function. She had bilateral internuclear ophthalmoplegia and mild right facial weakness of upper motor neuron type. Other cranial nerves were intact. Tone was normal, and power was 4/5 in right upper and lower limbs with symmetrically exaggerated deep tendon reflexes without clonus and bilateral equivocal plantar responses. Gait was broad-based and ataxic. Finger-nose coordination and heel-shin test were impaired on the left side. Fundus examination was normal.
Routine blood investigations, erythrocyte sedimentation rate, thyroid function tests, Vitamin B12 level, and vasculitis workup were normal. Computed tomography scan of the head and brain was done which showed diffuse brain atrophy. Magnetic resonance imaging (MRI) of the head and spinal cord with gadolinium contrast was performed. MRI of the brain showed multiple periventricular and subcortical hyperintense signal intensity lesions within both cerebral hemispheres and brainstem with evidence of postcontrast enhancement along the brainstem lesion. MRI of the spine revealed multiple intraluminal hyperintense signals on T2 sequence at the level of cervical and thoracic segments with pathological enhancement on postcontrast images. Possible causative lesions are shown in [Figure 1] and [Figure 2]. Electroencephalogram was normal. Cerebrospinal fluid analysis was normal, and oligoclonal bands were not detected. The final diagnosis of MS was made as the patient was fulfilling the 2010 McDonald diagnostic criteria.  Attacks were labeled as PD rather than focal onset seizures. During her stay, she received intravenous methylprednisolone at a dose of 1 g/day for 5 days. Carbamazepine was added for PD which reduced the frequency to one to three times during hospital stay. On follow-up, she was free of attacks.
|Figure 1: Magnetic resonance imaging of the brain, axial view showing hyperintense lesion in brainstem affecting the left cerebral peduncle on T2 weighted image|
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|Figure 2: Magnetic resonance imaging of the cervical spine, sagittal view showing hyperintense signal lesion in the cervical cord at the level of C2, C3 segments on T2 sequence|
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| Discussion|| |
MS is typically characterized by its relapsing and remitting nature. However, it is associated with other symptoms which may start suddenly and last only for few seconds, considered as paroxysmal phenomena. These paroxysmal phenomena are tonic spasm, paroxysmal dysarthria, hemiataxia, akinesia, paresthesia, itching, and trigeminal neuralgia. It is of utmost importance to recognize these stereotyped phenomena which can often be misdiagnosed as epileptic attacks. 
Tonic spasm whether painful (PTS) or not also termed as PD manifests as sudden onset dystonic posturing affecting either one or both extremities and sometimes neck as well with a stereotyped pattern. The attacks are of brief duration usually <2 min and occur several times a day. 
PD is the most frequently described movement disorder. In 1995, Tranchant et al. described 83 cases of PD in MS patients. 
Patients with MS can often develop PD before the emergence of other symptoms, sometimes even ten or more years. 
The most likely pathophysiologic explanation for PD in MS is an ephaptic activation of axons caused by the neural transmission at a nonsynaptic contact site within a demyelinating plaque at any level in a motor pathway.  Causative lesions have been described in various locations as the spinal cord, contralateral cerebral peduncle, posterior limb of internal capsule, thalamus, subthalamus, and semiovale center.  The lesions identified in contralateral cerebral peduncle and cervical segment of the spinal cord can be considered as the causative lesions in our patient.
Antiepileptic drugs are considered to be effective in treating PD. The most commonly used and effective medication is carbamazepine. , Carbamazepine was found effective in our case as well.
| Conclusion|| |
PD is a known but underrecognized manifestation of MS and can be mistaken as a focal onset seizure disorder. Lack of awareness can contribute to delay in diagnosis and inappropriate treatment. Carbamazepine can be an effective medication for PD.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]