A clinical profile of 103 patients with secondary movement disorders: correlation of etiology with phenomenology

Background and purpose: Studying patients with secondary movement disorders (SMD) provides a unique opportunity to determine the correlation between the etiology and phenomenology of movement disorders. Methods: This was a prospective study of 103 patients (43 women, 60 men; age = 28.7 +/- 17.3 years; range = 2-70 years) with SMD, in a tertiary hospital over 4 years. Results: The mean age of onset of SMD was 24.3 +/- 19.7 years, and duration of symptoms was 4.3 +/- 7.1 years (42 days to 40 years). Patients with pure tremor, pure dystonia (DYS), or a combination of tremor with dystonia had longest latency (10.9-18.5 months), whereas those with parkinsonism (PAR) and hemiballismus (HMB) had shorter latency (2.7-3.0 weeks). Pure dystonia was most prevalent (30.1%) followed by dystonia plus (13.6%), tremor (12.6%), PAR (11.7%), HMB (8.7%), mixed SMD (7.8%), tremor with dystonia (6.8%), myoclonus (5.8%), and chorea (2.9%). In approximately 60% of patients, the underlying etiologies were vascular (VAS), infections, and space-occupying lesions (SOL), and 25% had SMD following trauma or hypoxia (HYP). With reference to specific etiologies, the most frequent SMDs were tremor following SOL (46%), post-traumatic syndromes (25%), dystonia following HYP (56%), VAS lesions (50%), and infections (28%). With reference to specific SMDs, the most common etiologies were VAS for dystonia (39%), SOL for tremor (67%), and PAR (31%), and both SOL and trauma (37.5% each) for tremor with dystonia. Conclusions: Our study highlights the spectrum of SMDs and the lack of correlation between types of SMDs and underlying etiologies. Preventable causes such as infections, HYP, trauma, and kernicterus still play a major role in pathogenesis of SMD.