The pathology of essential tremor (ET) is increasingly being studied. The main findings include a reduction in cerebellar Purkinje cells, other pathological changes of cerebellar degeneration and restricted Lewy bodies in the locus ceruleus. This paper will review those findings and put them into context with clinical studies in ET and findings in neurodegenerative disorders such as Parkinson's disease.
"Another debated controversy is whether ET should be viewed as a mono-symptomatic (“benign”) disorder, or whether it is a syndrome of several diseases including neurodegenerative [6,13,14]. PD can be sometimes viewed as “benign” in some tremor-dominant (TD) patients, as it progresses very slowly . "
[Show abstract][Hide abstract] ABSTRACT: Essential tremor (ET) and Parkinson's disease (PD) are considered distinct disorders. The aim of the study was to look for a link or any distinguishing features by transcranial sonography (TCS), together with the clinical examination findings in a group of patients with overlapping phenotype of ET and PD (ET-PD).
A prospective observational case-control study was carried out from the 3rd January 2011 until 30th January 2013 at the Hospital of Lithuanian University of Health Sciences. The final study group consisted of 15 patients with ET-PD, 116 patients with ET-only and 141 patients with PD-only. The control group included 101 subjects. Clinical diagnosis was of a diagnostic standard.
The main ultrasonographic findings in the ET-PD group were similar to those of the PD-only: hyperechogenicity of the substantia nigra (66.7%, p < 0.001) and nuclei raphe interruptions/absence (38.5%, p < 0.001). The single distinguishing TCS finding in ET-PD group was a lentiform nucleus hyperechogenicity (26.7%), however this was only significant when compared to controls (p = 0.006). An asymmetrical onset of symptoms (73.3%) in ET-PD group was characteristic to PD-only. The ET-PD patients had the longest disease duration (median 6 years, p < 0.001), the most frequent rate of positive family history (53.3%, p = 0.005), rather low prevalence of cogwheel rigidity (26.7%, p < 0.001), and higher mean Hoehn & Yahr scores compared to PD-only (2.6 +/- 0.8 vs. 1.8 +/- 0.8, p = 0.012).
The main TCS findings of the present study in patients with overlapping ET-PD phenotype were similar to the PD-only group. The highest positive family history rate among ET-PD patients indicates a strong hereditary predisposition and needs genetic underpinnings. Some ET patients, who look like they may be developing co-morbid PD clinically, may have an alternative diagnosis for Parkinsonism, which could be delineated by TCS examination.
"Essential tremor (ET) is a progressive movement disorder found in human adults, with prevalence ranging from 4% in the population of age 40 years or older to 14% in those older than 65 years . Despite its prevalence, there is little known concerning the functional pathology of ET . Traditionally, ET has been regarded as a mono-motor symptomatic disease with postural or kinetic tremor(s) in the hands and forearms or isolated tremor(s) in the head and/or of the voice. "
[Show abstract][Hide abstract] ABSTRACT: Essential tremor (ET) is one of the most common movement disorders in human adults. It can be characterized as a progressive neurological disorder of which the most recognizable feature is a tremor of the arms or hands that is apparent during voluntary movements such as eating and writing. The pathology of ET remains unclear. Resting-state fMRI (RS-fMRI), as a non-invasive imaging technique, was employed to investigate abnormalities of functional connectivity in ET in the brain. Regional homogeneity (ReHo) was used as a metric of RS-fMRI to assess the local functional connectivity abnormality in ET with 20 ET patients and 20 age- and gender-matched healthy controls (HC). The ET group showed decreased ReHo in the anterior and posterior bilateral cerebellar lobes, the bilateral thalamus and the insular lobe, and increased ReHo in the bilateral prefrontal and parietal cortices, the left primary motor cortex and left supplementary motor area. The abnormal ReHo value of ET patients in the bilateral anterior cerebellar lobes and the right posterior cerebellar lobe were negatively correlated with the tremor severity score, while positively correlated with that in the left primary motor cortex. These findings suggest that the abnormality in cerebello-thalamo-cortical motor pathway is involved in tremor generation and propagation, which may be related to motor-related symptoms in ET patients. Meanwhile, the abnormality in the prefrontal and parietal regions may be associated with non-motor symptoms in ET. These findings suggest that the ReHo could be utilized for investigations of functional-pathological mechanism of ET.
PLoS ONE 07/2013; 8(7):e69199. DOI:10.1371/journal.pone.0069199 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The use of neuromodulatory techniques in the treatment of neurological disorders is expanding and now includes devices targeting the motor cortex, basal ganglia, spinal cord, peripheral nervous system, and autonomic nervous system. In this chapter, we review and discuss the current and past literature as well as review indications for each of these devices in the ongoing management of many common neurological diseases including chronic pain, Parkinson's disease, tremor, dystonia, and epilepsy. We also discuss and update mechanisms of deep brain stimulation and electrical neuro-network modulation.
International Review of Neurobiology 12/2012; 107:253-82. DOI:10.1016/B978-0-12-404706-8.00014-0 · 1.92 Impact Factor
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