Essential tremor is not a neurodegenerative disease PERSPECTIVE

„ Resting tremor, which is characteristic of Parkinson’s disease (PD), is also present in some essential tremor (ET) cases, and action tremor, which is characteristic of ET, is seen in PD cases, thus resulting in errors in diagnosis. „ Tremor in ET may interfere with passive movements at a joint and give an impression of cogwheel rigidity, especially if it is done with reinforcement. „ Rapid alternating movements used to determine bradykinesia may be interrupted by prominent tremor in ET cases, thus resembling arrest of voluntary movement – resembling bradykinesia. „ Impaired postural reflexes characteristic of stage 3 Hoehn and Yahr PD are also seen in many normal elderly patients. „ If a patient only has mild action tremor without convincing bradykinesia or rigidity, clinicians should wait for subsequent evaluation before making a diagnosis. „ In a patient with prominent tremor, assess the rigidity at the shoulder joint. Put one hand under the patient’s elbow, hold the wrist with your other hand, flex the elbow to approximately 90° and move the forearm to the left and right slowly to rotate the shoulder. The clinician may reinforce this action by asking the patient to rapidly tap the contralateral foot while moving the arm. „ For testing bradykinesia in a case with prominent tremor, use one finger tapping. Place the palm of the patient’s hand on a firm object such as a table. Hold down the small and ring fingers and thumb, and if necessary the middle finger to prevent movement. Ask the patient to tap their index finger rapidly but steadily, not ‘stop and go’. A decline in amplitude would indicate bradykinesia. „ In a patient under the age of 60 years, postural instability (pull test) without any other cause strengthens the diagnosis of PD, but in an individual over the age of 65 years, it has less significance.