Re-emergent tremor in Parkinson's disease: A clinical and electromyographic study.
BACKGROUND
Re-emergent tremor (ReT) in Parkinson's disease (PD) is the tremor that re-emerges after a variable period of latency while maintaining posture. The phenomenology and electrophysiological aspects of ReT have not been well characterized. The aims of this study were to characterize ReT clinically and electrophysiologically.


METHODS
Sixty three patients with tremor dominant PD were recruited and subjected to clinical and electrophysiological evaluations. Group 1 consisted of 26 patients with rest tremor (RT) and ReT and group 2 consisted of 37 patients with RT and postural tremor (PT). The presence of silent period of ReT was determined clinically and confirmed electrophysiologically.


RESULTS
The duration of illness was significantly shorter in patients with ReT as compared to patients without ReT (5.2±4.4years vs 7.4±4.5years, p=0.03). ReT was similar to RT in terms of both frequency (4.8±0.7Hz vs 4.7±0.6Hz, p=0.1) and pattern of contraction. The frequency of RT was not significantly different in the 2 groups (p=0.5). The mean duration of silent period was 8.1±8.7s.


CONCLUSIONS
A significantly shorter duration of illness was found in patients with ReT as compared to patients without ReT. ReT is similar to RT in terms of frequency and pattern of contraction. However, the presence of silent period may imply additional pathophysiological mechanisms.
Department of Neurology, National Institute of Mental Health & Neurosciences, Hosur Road, Bangalore 560029, Karnataka, India.
Pooja
P
Mailankody
Department of Neurology, National Institute of Mental Health & Neurosciences, Hosur Road, Bangalore 560029, Karnataka, India; Department of Biostatistics, National Institute of Mental Health & Neurosciences, Hosur Road, Bangalore 560029, Karnataka, India.
K
K
Thennarasu
Department of Neurology, National Institute of Mental Health & Neurosciences, Hosur Road, Bangalore 560029, Karnataka, India.
B C
BC
Nagaraju
Department of Neurology, National Institute of Mental Health & Neurosciences, Hosur Road, Bangalore 560029, Karnataka, India.
Ravi
R
Yadav
Department of Neurology, National Institute of Mental Health & Neurosciences, Hosur Road, Bangalore 560029, Karnataka, India. Electronic address: pal.pramod@rediffmail.com.
Pramod Kumar
PK
Pal
D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*; D011187:Posture / Q000502:physiology; D013997:Time Factors; D014202:Tremor / Q000209:etiology / Q000503:physiopathology*; D014953:Wrist / Q000503:physiopathology
EMG; Parkinson's disease; Postural tremor; Rest tremor; re-emergent tremor