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Query: UMLS:C0040822 (tremor)
 18,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Resting tremor is seen in both the limbs and in the trigeminal motor system. These rhythmical perturbations are the result of alternating activation of antagonistic muscles, and these increase in amplitude during slow, voluntary movements. In the present study, we examined the effect of experimental muscle pain on finger and jaw tremor. The tremor in the mandible and in the middle finger was measured on separate occasions, at rest and during two constant-velocity movements. Pain was then induced by the infusion of hypertonic saline into a jaw-closing muscle (masseter) or into a finger extensor muscle (extensor digitorum longus, EDL). During masseter pain, the power at the peak tremor frequency of the mandible decreased significantly both when the jaw was at rest and during voluntary jaw movements at two velocities. In contrast, pain in EDL resulted in a significant increase in the power of finger tremor only during the two speeds of voluntary movement. No change in the peak tremor frequency was seen in either the finger or the jaw during pain. The most likely explanation for these data is that muscle pain tonically modulates the amplitude of the outputs from the central "pulsatile control" generators that drive the alternating activation of antagonistic muscles which produce tremor at rest and during movements. This modulation is in the opposite direction for systems controlling jaw and hand, suggesting a specific interaction of the nociceptive afferents with separate central oscillators.
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PMID:Differential modulation of tremor and pulsatile control of human jaw and finger by experimental muscle pain. 1273 86

Introduction: The diagnosis of essential tremor (ET) remains a clinical one, and diagnostic errors are common. We aimed to (1) determine precisely how frequently ET diagnoses are misapplied (i.e., what percentage of patients who have been assigned an "ET" diagnosis actually have another movement disorder), (2) determine which other movement disorders are most often misclassified as "ET," and (3) examine the clinical features that were most associated with diagnostic errors. Methods: One hundred four consecutive patients were included who met the following criteria: (1) initial outpatient evaluation by one of the authors (EDL) between January 2015 and December 2019 and (2) pre-evaluation diagnosis of ET. Data on an extensive number of clinical features were extracted from the electronic medical record. Results: Forty-seven (45.2%) patients received a post-evaluation diagnosis of ET, 29 (27.9%) of dystonia, and 28 (26.9%) of other diagnoses including Parkinson's disease (PD) [6 (5.8%)]. Factors associated with an alternative post-evaluation diagnosis other than ET were pre-evaluation diagnosis made by a non-neurologist, shorter tremor duration, irregular tremor, abnormal limb postures, among others. Discussion: Diagnosing ET remains a challenge, with the diagnosis being over-applied and being used as a "waste basket." More than one-half of the patients who were referred to our clinic with an intake diagnosis of ET were given an alternative post-evaluation diagnosis. While PD was reported to be the most frequently missed diagnosis in a past study, dystonia was most commonly missed in our study. Several clinical features can help to differentiate ET from other tremor disorders.
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PMID:Essential Tremor as a "Waste Basket" Diagnosis: Diagnosing Essential Tremor Remains a Challenge. 3226 48