Rivastigmine for parkinsonian symptoms in dementia with Lewy bodies: a paradigm shift.

Parkinsonian symptoms are one of the core features of Dementia with Lewy bodies (DLB), which has a prevalence of more than 80%. Management of DLB poses unique challenges as the treatment of one condition leads to the worsening of another. Rivastigmine's efficacy and tolerability for cognitive and neuropsychiatric symptoms are well-studied. However, its effect on parkinsonian symptoms of DLB is inconclusive. In this case series, we elucidated five clinically diagnosed subjects of DLB with varying severity of parkinsonian motor symptoms. Beyond the cardinal signs of parkinsonism (tremor, rigidity, bradykinesia); rigidity, hypomimia, and gait disturbances were common in all the subjects. All five subjects on Rivastigmine dosage of 3-4.5 mg/day showed a greater than 50% reduction in the Unified Parkinson's Disease rating scale part III without any untoward side effects. Hypomimia, stiffness, gait, and postural abnormalities were the motor signs that were substantially improved while resting tremors showed the least improvement. The study findings focus on the need to reflect upon the non-cholinergic deficiency hypothesis in developing motor symptoms in DLB. The distinct pathophysiology of DLB and the complex interactions of cholinergic and dopaminergic neurons in the striatum can explain the improvement in parkinsonian symptoms with Rivastigmine. This case series highlights the positive effect of low-dose Rivastigmine on parkinsonian motor symptoms of DLB prompting the need for further multicentric trials.