Systematic clinical approach for diagnosing upper limb tremor

Abstract

Tremor is the most common movement disorder worldwide, but diagnosis is challenging. In 2018, the task force on tremor of the International Parkinson and Movement Disorder Society published a consensus statement that proposes a tremor classification along two independent axes: a clinical tremor syndrome and its underlying aetiology. In line with this statement, we here propose a stepwise diagnostic approach that leads to the correct clinical and aetiological classification of upper limb tremor. We also describe the typical clinical signs of each clinical tremor syndrome. A key feature of our algorithm is the distinction between isolated and combined tremor syndromes, in which tremor is accompanied by bradykinesia, cerebellar signs, dystonia, peripheral neuropathy or brainstem signs. This distinction subsequently informs the selection of appropriate diagnostic tests, such as neurophysiology, laboratory testing, structural and dopaminergic imaging and genetic testing. We highlight treatable metabolic causes of tremor, as well as drugs and toxins that can provoke tremor. The stepwise approach facilitates appropriate diagnostic testing and avoids unnecessary investigations. We expect that the approach offered in this article will reduce diagnostic uncertainty and increase the diagnostic yield in patients with tremor.

Keywords: dystonia; myoclonus; neurophysiol, clinical; parkinson's disease; tremor.

Figure 1

Eight-step diagnostic approach to upper limb tremor. DT, dystonic tremor; EPT, enhanced physiological tremor; ET, essential tremor.

Figure 2

Practical clinical algorithm. Isolated tremor syndromes are depicted in blue on the left side of the diagram, combined tremor syndromes in orange on the right side. Functional tremor is depicted in green on the right side. *For example, mildly unsteady tandem gait, questionably abnormal posturing of a body part, mild cognitive impairment, questionable bradykinesia or rigidity and other mild neurological signs of unknown significance that do not suffice to make an additional syndrome classification or diagnosis. †For example, anxiety, fatigue, thyrotoxicosis, hypoglycaemia, pheochromocytoma, tremor-provoking medication (see table 1).