Thalamic physiology of intentional essential tremor is more like cerebellar tremor than postural essential tremor

• Published in: Brain research 2013-09, Vol.1529, p.188-199
• Main Authors: Zakaria, R, Lenz, F.A, Hua, S, Avin, B.H, Liu, C.C, Mari, Z
• Format: Article
• Language: English
• Subjects: Action Potentials - physiology; Adult; Aged; Biological and medical sciences; brain; Cerebellum - pathology; Cerebellum - physiopathology; Deep Brain Stimulation - methods; Electromyography; Essential tremor; Essential Tremor - pathology; Essential Tremor - physiopathology; Essential Tremor - therapy; Evoked Potentials, Motor; Female; Functional Laterality; Fundamental and applied biological sciences. Psychology; Human thalamus; Humans; infarction; Intention; Intention tremor; Magnetic Resonance Imaging; Male; Medical sciences; Middle Aged; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Nervous system (semeiology, syndromes); Nervous system as a whole; Neurology; neurons; Neurons - physiology; Pacemaker; Pain - surgery; patients; physiology; Posture - physiology; Single neuron analysis; Statistics, Nonparametric; stroke; surgery; Thalamus - pathology; Thalamus - physiology; Vertebrates: nervous system and sense organs; Wrist - innervation
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2013.07.011

Abstract The neuronal physiological correlates of clinical heterogeneity in human essential tremor are unknown. We now test the hypothesis that thalamic neuronal and EMG activities during intention essential tremor are similar to those of the intention tremor which is characteristic of cerebellar lesions. Thalamic neuronal firing was studied in a cerebellar relay nucleus (ventral intermediate, Vim) and in a pallidal relay nucleus (ventral oral posterior, Vop) during stereotactic surgery for the treatment of tremor. Nine patients with essential tremor were divided clinically into two categories: one with a substantial component of tremor with intention (termed intention ET ) and the other without ( postural ET ). These types of essential tremor were compared with patients having intention tremor plus other clinical signs of cerebellar disease ( cerebellar tremor ). Neurons in patients with either intention ET or cerebellar tremor had lower firing rates and lower spike×EMG coherence than those in patients with postural ET. Patients with intention ET had a lower spike×EMG phase lead than those with postural ET. Overall, thalamic activity measures of intention ET were different from postural ET but not apparently different from those of cerebellar tremor. One patient with the intention ET (number 4) had a good response to a left thalamotomy and then suffered a right cerebellar hemispheric infarct five years later. After the stroke the intention ET recurred, which is consistent with our hypothesis that intention ET is similar to that of the intention tremor which is characteristic of cerebellar lesions.