Paroxysmal Dystonia in Inflammatory Disorders of the Central Nervous System. a Southeastern Michigan Cohort Study

Background: Paroxysmal Dystonia (PD) is a recurrent, neurological symptom characterized by sustained muscle contraction, frequently causing twisting and repetitive movements, or abnormal postures that persists seconds to minutes. This infrequent symptoms are less recognized in general practice although they have been described in inflammatory disorders of the central nervous system (CNS) specifically, in Multiple Sclerosis (MS) and Neuromyelitis Optica (NMO).  

Objectives: To evaluate the presentation and treatment of paroxysmal dystonia (PD) in patients with inflammatory disorders of CNS.

Methods:  Study setting was in a large integrated health care system serving residents of southeastern Michigan. Over the course of 5 years, 17 patients with inflammatory disorders of CNS presented with paroxysmal symptoms. Electronic medical records were reviewed retrospectively and data was collected on diagnosis, socio-demographic factors, neurological symptoms, MRI imaging, treatment regimen and treatment response. Descriptive statistics were used to characterize the PD cases. The Institutional Review Board approved this study.

Results: Of the 17 patients with paroxysmal symptoms, 8 (47%) patients with MS and 3 (17%) with NMO presented with PD.  The average age at presentation was 46.1 years (range 35-55) for MS and 47.6 years (range 36-60) for NMO. The female to male ratio was 1:1 in the MS group, while NMO patients were all female. Four (50%) patients had already an establish diagnosis of relapsing remitting MS at symptom presentation while in 4 (50%) PD was the first symptom of MS.  Two patients in the NMO group developed paroxysmal dystonia after the initial acute phase of transverse myelitis, which had lead to a definitive diagnosis for NMO, whereas one patient developed the symptoms a few weeks following a relapse in the form of transverse myelitis.  T2 FLAIR MR images showed new lesions in MS patients corresponding to symptoms in areas of midbrain (1/8), pons (1/8), medulla (1/8), posterior limb of internal capsule (1/8), thalamus (1/8), basal ganglia (1/8), cerebral peduncle (1/8) and cerebellar peduncle (1/8).

Seven (87.5%) patients in MS group responded to monotherapy in less than 8 weeks from symptom onset. 5/7 received carbamazepine; 1/7 oxcarbazepine; 1/7 gabapentin. Patients with NMO required a combination of several agents and resolution of symptoms took up to 24 months.

 Conclusions: Recognition of paroxysmal dystonia as a neurological symptom in MS is important, especially since this can be a presenting feature of the disease. In NMO it is important to be aware that these symptoms can occur after the active stage of transverse myelitis. Unlike many other manifestations of MS, paroxysmal dystonia is frequently abolished with monotherapy, whereas this manifestation in the NMO group requires a multi-therapeutic approach and a longer duration before symptom resolution.