Objective: To present cases of patients with diagnostic uncertainty between tremor in Parkinson’s disease (PD) and dystonic tremor.

Background: Some patients with clinical presentation of parkinsonian tremor might have negative DaT-SPECT, what exclude PD. On the other hand, patients with PD could experience action tremor, different from the rest one. It is often not possible to distinguish different types of tremor only by clinical examination, what can result in insufficient effect of therapy.

Method: We examined four patients with PD and atypical or refractory tremor with Neuro-MEP-8CH EMG machine in different situations.

Results: Case 1: 78-year woman complained about asymmetrical tremor of limbs, head and voice (for 7 years). Despite negative DaT-SPECT, she had been diagnosed with PD. On EMG, we confirmed asymmetrical, mainly action limb tremor, with some bursts of subcortical myoclonus, co-contractions and overflow activity. There were no signs of typical parkinsonian tremor, and findings were too asymmetrical and irregular in frequency to resemble ET. We concluded dystonic tremor. Case 2: 87-year old women with 1 year history of left-hand tremor, mainly at rest, but also in posture, worsened by stress, accompanied with typical asymmetrical rigidity and hypokinesia, with improvement with L-dopa. We confirmed asymmetrical 4Hz rest tremor worsened with mental task. In addition, we found 7Hz postural tremor with co-contractions and overflow activity. Patient had both parkinsonian and dystonic tremor. Case 3: 67-year old man had 4 year history of rather symmetrical tremor of both hands, mainly kinetic, affecting activities of daily living. On polymyography, we recorded 5Hz rest component worsened with mental task, and postural component composed of bursts of subcortical myoclonus accompanied by co-contraction and overflow activity. We concluded dystonic and parkinsonian tremor. Patient is awaiting his DaT-SPECT. Case 4: 74-year old woman complained about jaw tremor worsened with stress, and only mild action asymmetrical upper limb tremor, for the last year. On the limbs, we detected 8-10Hz action tremor with co-contraction and overflow activity. In masseter muscle, there was 7Hz tremor. This supports the diagnosis of dystonic tremor.

Conclusion: Polymyography helps to distinguish various types of rest, postural and kinetic tremor in patients diagnosed with PD. DaT-SPECT can disentangle the diagnosis in unclear cases.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/dystonic-versus-parkinsonian-tremor/