Correspondence Address: Dr. Boby Varkey Maramattom Lead Consultant Neurologist , Dept of Neurology, Aster Medcity, Kochi - 682 023, Kerala India
Source of Support: None, Conflict of Interest: None
How to cite this article: Maramattom BV. Paroxysmal Dysarthria Ataxia–Tremor–Blepharospasm Syndrome in Bickerstaff Brainstem Encephalitis: A Variant of Paroxysmal Dysarthria Ataxia Syndrome. Neurol India 2019;67:1388-9
How to cite this URL: Maramattom BV. Paroxysmal Dysarthria Ataxia–Tremor–Blepharospasm Syndrome in Bickerstaff Brainstem Encephalitis: A Variant of Paroxysmal Dysarthria Ataxia Syndrome. Neurol India [serial online] 2019 [cited 2021 Jun 24];67:1388-9. Available from: https://www.neurologyindia.com/text.asp?2019/67/5/1388/271246
A 49-year-old male was admitted with diplopia of a two month duration. Magnetic resonance imaging (MRI) of the brain showed midbrain T2/fluid attenuated inversion recovery (FLAIR) symmetrical hyperintensities with mild diffusion restriction and he was treated for a midbrain infarct [Figure 1]. Six weeks later he was readmitted with progressive difficulty in walking, generalized weakness, and diplopia along with numbness over the left side of the face after poor food intake. On examination he had bilateral ptosis, upgaze restriction, dysarthria, intention tremors in both arms, gait ataxia, and generalized areflexia. MRI showed symmetrical bithalamic and upper midbrain hyperintensity on T2/FLAIR images without diffusion restriction or contrast enhancement [Figure 1] and [Table 1]. He was administered high-dose thiamine for possible wernicke's encephalopathy and and discharged with partial improvement. One month later, he returned with worsening gait ataxia and hypersomnolence. At this point, Bickerstaff brainstem encephalitis (BBE) was considered. He was treated with a 5-day course of IV methylprednisolone without improvement. Serum ceruloplasmin came back low (8 mg/dl). However, a 24 hour urine copper estimation was normal. He then underwent six cycles of plasma exchange on alternate days. Following this, his symptoms improved and he was discharged. Other testing for HLA B51, very long chain fatty acids (VLCFAs), paraneoplastic antibodies, KF ring, and whole body PET-CT were negative. Six weeks later he returned with an intermittent head tremor and gait disturbance. These occurred usually on standing or sitting and abated on lying down; around 100–200 times a day and each lasting around 1–2 minutes. Episodes were characterized by a paroxysmal side to side head tremor, head tilt to the left, and dysarthria, along with blepharospasm lasting for <1 min [Video 1]. The episodes ended abruptly and the head tremor could be ameliorated by touching the left chin (Geste antagoniste) [Video 2]. During walking, episodes precipitated gait ataxia. The possibility of a paroxysmal dysarthria ataxia syndrome (PDA) was considered and he was started on 600 mg of carbamazepine a day. In a week, the number and intensity of episodes had reduced by >90%.
Figure 1: Axial MRI images (diffusion, FLAIR, T2, and post-contrast T1) at the level of the midbrain (top panel at admission and bottom panels 1.5 months later) showing hyperintensities without contrast enhancement
Anti-GQ1b antibody test and genetic testing for Wilson disease was negative. The final diagnosis was an atypical BBE. At follow-up 6 months later, he had improved by over 90% with carbamazepine.
PDA syndrome is characterized by recurrent, brief, stereotyped episodes of dysarthria, and limb ataxia and is classically associated with demyelinating diseases like multiple sclerosis (MS). The key lesion is in the midbrain in the vicinity of the red nucleus. Paroxysmal features are thought to be caused by ephaptic transmission in the cerebello–thalamo–cortical pathways. PDA is classified into two types: (1) primary or essential PDA (pPDA, associated with episodic ataxia) or (2) secondary to underlying neurological illnesses (secondary PDA [sPDA]). Other conditions associated with PDA include midbrain infarction, Behcets syndrome, and Bickerstaff encephalitis.,,
sPDA may be distinguished from pPDA by adult onset, brevity of episodes (<1 min) and response to carbamazepine rather than acetazolamide (used in EA). Lacosamide, fingolimod, and lamotrigine have also been tried.,, PDA syndrome may also remit spontaneously in MS. In conclusion, our patient had an atypical BBE syndrome with sPDA. MRI showed a symmetric midbrain lesion and his sPDA syndrome responded well to carbamazepine.
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