A cross-over clinical and electromyographic assessment of treatment for parkinsonian tremor

BACKGROUND: Whether dopaminergic and anticholinergic drugs exert influence on parkinsonian rest and postural tremor is a subject of debate. Different types of tremor may be influenced differently by the drugs. The aim of this study was to reevaluate the differential effects of levodopa and anticholinergic drugs on parkinsonian tremor in different limb positions and on different types of postural tremor. METHODS: Thirty-eight patients with parkinsonian resting tremor and postural tremor were included in this study. Patients were divided into two groups according to the electromyographic pattern of the postural tremor. We found fast synchronous postural tremor (>7 Hz) in 16 patients, and slow alternating postural tremor in 22 patients. The tremor was scored clinically in each limb position using the Webster Tremor Scale. Surface electromyographic recordings from the most involved limb in all positions were also performed. The patients were randomly assigned to levodopa (one 250/50-mg tablet), or to biperiden (one 3-mg tablet). Tremor was assessed by clinical and electromyographic examinations at base line 1h following ingestion of the drug. The subjective tremor improvement was also assessed. RESULTS: We found that levodopa had a good effect on the amplitude of the resting tremor, while the effect of biperiden was weaker. Both levodopa and biperiden has less effect on postural tremor. However, levodopa's effect was better than that of biperiden. Levodopa and biperiden had better effect on slow alternating postural tremor than on fast synchronous postural tremor. They had no effect on kinetic and intention tremors. CONCLUSIONS: Levodopa and anticholinergic drugs have differing effects on both resting and postural tremor Also, the different categories of postural tremor respond differently to treatment. The mechanisms underlying resting parkinsonian tremor may be different from those underlying postural, kinetic and intention tremor. Moreover, the mechanisms underlying different types of postural tremor may be different.     

Differential effects of changes in mechanical limb properties on physiological and pathological tremor.

The effect of changes in mechanical limb properties on the peak frequency of different tremor forms was analysed. Wrist tremor was recorded by an accelerometer fixed to the dorsum of the hand and demodulated surface EMG was recorded from the wrist extensors, while the extended hand was loaded with successively heavier weights. Physiological tremor was characterised by flat EMG spectra and a gradual decrease in tremor peak frequency with increasing load, as would be expected from the properties of a passive spring-mass-system. Also the peak frequency of activated physiological tremor characterised by increased synchronisation between motor units decreased in frequency with increasing loads. EMG spectra showed clear peaks of activity at the various mechanically determined tremor frequencies. In contrast, in two pathological tremor forms, the postural tremor in Parkinsonian patients and essential tremor, peak frequency tended to remain stable irrespective of changes in load. The method therefore allows a simple distinction between physiological and these two pathological tremors.     

Electromyographic differentiation of tremors.

OBJECTIVE: The aim of this study was to explore the opportunity for differentiation of tremors on the basis of the electromyographic examination. METHODS: We report data from 525 patients with different types of tremor included in this study. Two hundred and twenty patients with essential tremor, 110 patients with Parkinson's disease, 24 patients with midbrain tremor, 22 patients with cerebellar tremor, 120 patients with enhanced physiological tremor due to anxiety, and 29 patients with psychogenic tremor participated in the study. A detailed neurological and electromyographic examination was performed. The tremor was studied in all limbs positions. Surface electromyographic recordings of the most involved body part were performed to all patients. RESULTS: According to the electromyographic examination all patients were divided to two groups: Patients with synchronous tremor and patients with alternating tremor in the antagonist muscles. The comparisons were performed only between the patients with tremor caused by different etiology within the group of synchronous or alternating tremor. The group of tremors with synchronous pattern included the patients with essential tremor type A (with synchronous activity), cerebellar, and enhanced physiological tremor. The group of tremors with alternating pattern included patients with Parkinsonian tremor, essential tremor type B (with alternating activity), rubral, and psychogenic tremors. Our results revealed that electromyographic examination of tremor pattern, frequency, amplitude, and burst duration is useful for tremor differentiation. CONCLUSION: The electromyographic examination may serve as a tool for differentiation of tremors.     

Modulation of postural wrist tremors by magnetic stimulation of the motor cortex in patients with Parkinson's disease or essential tremor and in normal subjects mimicking tremor

The effect of magnetic brain stimulation on postural wrist tremor was studied in 10 patients with Parkinson's disease, 12 with hereditary essential tremor, and 10 normal subjects who mimicked tremor by making rapid alternating wrist movements. In all patients and normal subjects, magnetic brain stimulation over the contralateral motor cortex at an intensity approximately 10% above threshold produced the following sequence of events: (1) a small direct electromyographic (EMG) response, followed by (2) suppression of the rhythmic EMG activity responsible for the tremor, before (3) reappearance of the tremor time-locked to the stimulus. It is concluded that magnetic brain stimulation over the motor cortex can modulate the oscillatory mechanisms responsible for the generation of postural tremors. Group analysis revealed that the time to reappearance of rhythmic EMG activity varied significantly with the period of parkinsonian postural tremors, but not with the period of essential or mimicked tremors. Magnetic stimulation also significantly shortened the period of parkinsonian postural tremors, but did not influence the period of essential or mimicked tremors. These behavioral differences indicate differences in the pathophysiological mechanisms underlying parkinsonian postural tremor and essential tremor.     

Limb positioning and magnitude of essential tremor and other pathological tremors

We examined the influence of maintaining different postural configurations of the upper extremity on the magnitude of tremor in patients with essential tremor and with postural tremor from a variety of other neurological disorders. Patients maintained postures requiring different angles of forward flexion in the sagittal plane, of horizontal flexion, and of elbow extension. The tremor of patients diagnosed with essential tremor was either unaffected or affected only little by changes in limb position. In contrast, patients with pathological tremors, of the cerebellar postural, parkinsonian, and other types, exhibited positional dependence of their tremor. When there was positional dependence of tremor, it was always largest when the hands were near the nose or chin. These observations suggest a practical method for assistance with the clinical discrimination of essential tremor from other postural tremors.     

The phenomenology of parkinsonian tremor

The definition of Parkinsonian tremor covers all different forms occurring in Parkinson's disease. The most common form is rest tremor, labelled as typical Parkinsonian tremor. Other variants cover also postural and action tremors. Data support the notion that suppression of rest tremor may be more specific for PD tremors. Several differential diagnoses like rest tremor in ET, dystonic tremor, psychogenic tremor and Holmes' tremor may be misinterpreted as PD-tremor. Tests and clinical clues to separate them are presented.     

Kinetic predominant essential tremor: successful treatment with clonazepam

Fourteen patients with marked kinetic tremors of long duration but no other major neurologic signs are described. A positive family history of essential tremor, mild postural tremor, and tremor suppression with alcohol suggest that the condition is a variant of essential tremor. Kinetic tremors had a frequency of 3.5 to 6.0 Hz and an alternating EMG pattern. Propranolol caused improvement in some patients, but clonazepam treatment resulted in tremor suppression in all patients. Kinetic tremor without cerebellar signs is a subtype of essential tremor with pharmacologic responsiveness to clonazepam.     

Side-to-side correlation of muscle activity in physiological and pathological human tremors.

OBJECTIVE: Many tremors occur always or often bilaterally. The question arises whether this could be explained by a common source or commonly transmitting pathways or by bilaterally represented, independent structures with the same oscillatory properties. A similar tremor frequency does not provide sufficient information to clarify this question. METHODS: We analyze coherencies between surface electromyographies (EMG) to investigate if bilateral physiologic (PT), essential (ET), Parkinsonian (PD) and orthostatic (OT) tremors originate from a common source for both sides of the body. We show that commonly used techniques to test whether coherencies are significant could lead to false positive results for tremor EMGs. A new estimation procedure is proposed to test EMG tremor time series on their linear independence. We apply this test to bilateral tremors. RESULTS: All measured EMG-pairs in OT (n = 7) were highly coherent between both sides with reproducible coherency values of up to 0.99. All other investigated tremors, i.e. PT and enhanced physiological tremors (EPT, n = 117), ET (n = 76) and PD resting and postural tremors (n = 70) do not show a significant side-to-side correlation. CONCLUSIONS: This finding shows that the pathophysiologies of OT and other pathological tremors are definitely different. Either they have different origins or different kinds of transmitting pathways. The proposed method might also be used to investigate other electrophysiological data and is a helpful, easy to use investigation for a daily clinical routine.     

Clinical and electromyographic examinations of patients with essential tremor

BACKGROUND: It is believed that no clinical differences exist among essential, familial and senile tremor, or between the tremor with synchronous or alternating electromyographic activity. The aim of this study was to evaluate the clinical and electromyographic findings in a large group of patients with different types of essential tremor. METHODS: Two hundred and twenty patients with sporadic, familial or senile variants of essential tremor were examined. According to the electromyographic activity recorded from the antagonistic muscles, the patients were subdivided into a group with synchronous (SYN) and a group with alternating (ALT) activity. The historical aspects of the disease were noted, and a detailed neurological examination was performed. RESULTS: A widespread tremor involving upper and lower limbs and 3-4 different anatomical regions was typical for familial tremor. It also had higher amplitude than the sporadic and senile tremor. ALT tremor had a higher amplitude and longer burst duration than SYN and more often involved lower limbs. Rest tremor was common in the ALT group. Overall, ALT tremor was more common than previously supposed. CONCLUSION: The familial and ALT tremors are more disabling than other types of essential tremor. Since electromyographic ALT activity is common in essential tremor, its presence does not reliably distinguish essential and Parkinsonian tremor.     

Tremor

Tremor is one of the most frequent neurological signs; the diagnosis is mainly clinical. The most frequent tremor is essential tremor, which manifests itself as a postural and kinetic tremor. Tremor may occur not only in the hands, but also in the head and voice. Parkinsonian tremor is a tremor at rest; the legs and face are frequently involved. Orthostatic tremor mainly manifests itself in the legs and gives rise to postural instability. Dystonic tremor is an action tremor of the affected region of the body. Drug therapy mostly depends on the clinical manifestation. Postural and action tremors respond to beta blockers, primidone, some antiepileptics and benzodiazepines. Classical rest tremors are improved by dopaminergic substances or anticholinergics. Dystonic tremor may be successfully treated by injecting botulinum toxin. Orthostatic tremor responds to gabapentin or benzodiazepines in some patients. In patients with severely disability, implantation of thalamic stimulation electrodes may be considered.     

Tremor in neuropathies of different origin

Background and purposeTremor accompanies some polyneuropathies, but its prevalence and its clinical and electrophysiological manifestations are not well known. The aim of the study was to assess the occurrence and characteristics of hand tremor in patients with polyneuropathy of different origins, as well as relations between the occurrence of tremors and clinical and neurographic findings of polyneuropathy.Material and methodsEighty-nine patients diagnosed with polyneuropathy of known aetiology, and 50 age- and sex-matched healthy volunteers were included in the study. All subjects were interviewed regarding the occurrence of tremor. Tremor was assessed clinically and objectively using a triaxial accelerometer and electromyographic (EMG) recordings. A load test with a weight of 500 g was performed in order to differentiate between enhanced physiological tremor (EPT) and essential tremor-like (ET-L) tremor.ResultsTremor was found in 59.5% of patients in clinical assessment and in 74% of patients in objective evaluation, significantly more often than in controls (12%). Tremor was detected in all types of polyneuropathy apart from paraproteinaemic IgM polyneuropathy. Tremor was postural (70%), but resting (51%) or kinetic (32%) tremor was also present. In the majority of cases, the severity of the tremor was mild. Essential tremor-like tremor prevailed in the study group. The occurrence of hand tremor was not related to the axonal or demyelinating type of polyneuropathy, nor to the conduction velocity or other electrophysiological findings of the investigated upper limb nerves.ConclusionTremor accompanies 60–70% of patients with polyneuropathy; it is mostly postural, ET-L type with mild severity, and unrelated to other typical clinical and electrophysiological findings of neuropathy.     

震颤分析在帕金森病和原发性震颤鉴别诊断中的应用

目的 探讨震颤分析在帕金森病(parkinson's disease,PD)和原发性震颤(essential trem-or,ET)鉴别诊断中的应用价值.方法 选取2017年9月至2020年11月在福建省立金山医院门诊和住院确诊的PD患者27例(PD组)和ET患者23例(ET组),所有患者均至少有一侧上肢静止性或姿势性...     

Tremor is attenuated during walking in essential tremor with resting tremor but not parkinsonian tremor

We used accelerometry and visual examination by a neurologist to measure the intensity and frequency of hand tremor under resting, postural, writing, and walking conditions among patients with essential tremor with resting tremor (n = 11) and Parkinson’s disease (n = 38). The intensity of essential tremor was markedly attenuated during walking relative to resting. The intensity and frequency of parkinsonian tremors were higher while walking than while resting. We suggest that assessment of the intensity and frequency of tremor during walking is clinically useful for differentiating between essential tremor with resting tremor and parkinsonian tremor, especially in the early stages, when the two conditions are often difficult to distinguish. Parkinsonian tremors are known to be enhanced during walking. Our clinical experience, as well as that of others, suggests that the intensity of essential tremor with resting tremor is markedly attenuated during walking.     

The effects of hypnosis on a parkinsonian tremor: case report with polygraph/EEG recordings

Although Parkinsonian tremors typically disappear during sleep and are reduced during relaxation periods, the effects of hypnosis on this type of movement disorder have been generally ignored. We observed a patient's severe Parkinsonian tremor under hypnosis and monitored it with EEG and EMG studies. The patient was taught self-hypnosis and performed it three to four times daily in conjunction with taking medication. The results suggest that daily sessions of self-hypnosis can be a useful therapeutic adjunct in the treatment of Parkinsonian tremors.     

Tremors in early Parkinson's disease

We examined 50 untreated parkinsonian patients with a complaint of tremor for the presence of a resting, postural, or kinetic tremor. Tremors were recorded by an accelerometer to determine amplitude and frequency. A postural tremor was present in 92% and a resting tremor in 76%. The amplitude of postural tremor was greater than resting tremor in 50%, the same in 25%, and less in 25%. The average tremor frequency of resting and postural tremor was not significantly different. Carbidopa/levodopa reduced testing tremor in 58% and postural tremor in 46% of patients. The dopamine agonist naxoglide (PHNO) reduced resting tremor in 77% and postural tremor in 70% of patients. Postural tremor was not worsened by either drug. It is concluded that tremors in both the resting and postural positions are an integral part of the symptoms of Parkinson's disease and that both tremors have a similar frequency and pharmacological responsiveness in the early phases of the disease.     

Modulation of postural tremors at the wrist by supramaximal electrical median nerve shocks in essential tremor, Parkinson''s disease and normal subjects mimicking tremor.

The response of postural wrist tremors to supramaximal median nerve stimulation was examined in patients with hereditary essential tremor (n = 10) and Parkinson's disease (n = 9), and in normal subjects mimicking wrist tremor (n = 8). The average frequency of on-going tremor was the same in all three groups. Supramaximal peripheral nerve shocks inhibited and then synchronised the rhythmic electromyographic (EMG) activity of all types of tremor. The duration of inhibition ranged from 90 to 210ms, varying inversely with the frequency of on-going tremor. There was no significant difference in mean duration of inhibition or in the timing of the first peak after stimulation on the average rectified EMG records between the three groups. The degree to which supramaximal peripheral nerve shocks could modulate the timing of rhythmic EMG bursts in the forearm flexor muscles was also quantified by deriving a resetting index. No significant difference in mean resetting index of the three groups was found. These results suggest that such studies cannot be used to differentiate between the common causes of postural wrist tremors.     

Contralateral hemi-parkinsonism and atypical tremor after stroke (a case report)

Extrapyraramidal parkinsonian-like syndromes have been observed as manifestations of different central nervous system lesions. A 45-year-old-man gradually developed tremor and slowing of movements 2 years after a stroke. Neurological examination revealed slight hemiparesis, muscle rigidity and bradykinesia in the left limbs. A tendency for hypomimia and impaired postural reflexes were found. There were resting, more pronounced postural and kinetic and most pronounced intentional tremors involving the left limbs. On electromyographic examination the static tremor was of 4Hz frequency, while the postural, kinetic and intention tremors were of 7Hz frequency. All tremors were with alternating activity in antagonist muscles. In conclusion our findings confirm the common anatomical basis of parkinsonism and essential like tremor. Both can appear after disruption of the pathways within and adjacent to the basal ganglia.     

Multiple sclerosis tremor and the Stewart-Holmes manoeuvre.

The objective of this study is to define tremor and cerebellar dysfunction and determine whether kinetic and postural tremor correlate with cerebellar dysfunction in patients with multiple sclerosis (MS). Cerebellar symptoms such as dysmetria often interfere with tremor evaluation in MS. The Stewart-Holmes (SH) manoeuvre, which has been recently quantified, may offer a selective evaluation of cerebellar dysfunction in such patients. Thirty-two patients with definite MS and arm tremor were evaluated (simplified Fahn tremor scale for kinetic and postural tremor, finger-to-nose test, clinical SH manoeuvre, quantitative study of the SH manoeuvre). Median severity of kinetic and postural tremor on the most disabled side was, respectively, 2 (range 0-4) and 1.5 (range 0-4). Clinical SH scores were moderately correlated to quantified SH measures (r = 0.36, P < 0.05). Kinetic and postural tremors were strongly correlated (r = 0.73, P < 0.0001) but did not correlate with clinical or quantified SH scores. Patients with bilateral tremor had higher scores for quantified SH, and a trend to higher clinical SH and finger-to-nose scores than patients with unilateral tremor. Although clinically associated, cerebellar dysfunction and tremor may be partly independent symptoms, suggesting they may relate to dysfunction of different neuronal systems. The SH manoeuvre should be part of the evaluation of MS patients considered for surgery of tremor.     

The dynamics of resting and postural tremor in Parkinson's disease.

OBJECTIVE: The study examines the time and frequency structure of Parkinson's disease tremor in patients that exhibit no clinical signs of tremor. METHODS: Eight mild to moderate Parkinson's disease and 8 matched control subjects maintained their limb in a constant position (30 s) under a postural finger, postural hand and resting tremor condition. Finger acceleration from the middle phalange, electromyographic (EMG) activity from extensor digitorum communis and flexor digitorum superficialis (FDS) were recorded. RESULTS: The data confirmed that there were no differences in the amount of limb motion and the modal frequency was around 9 Hz for each subject group. The time-dependent organization of tremor was more regular (lower approximate entropy [ApEn]) in Parkinson's disease. Both time and frequency analyses between the acceleration and extensor EMG signals demonstrate a reduction in the 20-25 Hz tremor component and an increase in the 8-12 Hz region of tremor. CONCLUSIONS: The results are discussed in relation to the proposal that increased regularity results from an increase in motor unit synchronization at 8-12 Hz and a reduction in the amplitude of the 20-25 Hz tremor component. The time and frequency structure of tremor may be useful in assessing individuals with Parkinson's disease.     

Difference of disability between electrophysiologic subgroups of essential tremor

OBJECTIVE: The aim of the study was to test the validity of the controversial subdivision of essential tremor (ET) patients into electrophysiological subgroups. METHODS: We evaluated a hundred patients with ET using surface electromyographic (EMG) recordings of antagonists forearm muscles and distinguished three groups: the first group showed synchronous activity of antagonistic muscles, the second showed alternating activity of antagonist muscles; and the third group consisted of patients whose EMG recordings were not compatible with the other two groups. We compared patients with synchronous and alternating activity in terms of sex, age at onset, duration of illness, family history of tremor, symmetry and frequency of tremor, and the scores of a disability scale. RESULTS: The only significant difference between the patients with synchronous and alternating activity was that the patients with synchronous activity were more disabled. CONCLUSION: This result adds to the evidence for distinct electrophysiological subgroups of ET with distinct clinical properties.