Improvement of Primary Writing Tremor in Parkinson's Disease with Carbidopa/Levodopa

Primary Writing Tremor: Current Concepts

Primary Writing Tremor (PWT) is a type of task specific tremor which happens only while writing (Type A PWT) or assuming a writing position of the hand (Type B PWT). There is a considerable overlap of clinical features between PWT and writer's cramp which creates difficulty in diagnosing this condition in the clinic. PWT usually affects the dominant hand and is typically 5-7hz in frequency, worsened by anxiety, temporarily relieved by alcohol and associated with reduced writing speeds. There are a variety of hypotheses about the phenomenology of PWT (regarding whether it is a variant of essential tremor, focal dystonia or an independent entity). Unlike writer's cramp, PWT shows normal reciprocal inhibition of H reflex, does not exhibit excessive EMG activity in proximal muscles, and on fMRI shows underactivation of cingulum and overactivation of primary motor and supplementary areas. There are no randomised controlled trials currently for the treatment of PWT. Treatment modalities available are: medical treatment, botulinum toxin, surgical management (including DBS) as well as adaptive strategies and occupational therapy.

Task Specific Tremor Subsequently Developing into Parkinson's Disease: Case Series

Background

Parkinson's Disease (PD) can present with dystonia or essential tremor but task specific tremor (TST) preceding PD has been only rarely reported. The relationship between TST and PD is unclear. We report a series of 12 patients with TST who later developed PD.

Cases

Patients with TST and PD were identified from our database. Records and imaging were reviewed and descriptive statistics presented. Twelve patients were identified. All 11 patients who had TST of arm developed rest tremor ipsilateral to the TST arm. DaTscan showed reduced dopaminergic uptake in all 11 patients who were scanned. The TST improved with STN and VIM DBS (3/12) and partially to dopaminergic medications (N = 3) and trihexyphenidyl (N = 2).

Conclusion

Rest tremor consistently occurring ipsilateral to TST, positive DaTscan, and partial response to dopaminergic medications but not to ET medications suggests TST is a precursor to PD in this population rather than chance occurrence.