A case of orthostatic tremor in parkinsonism

A 79-year-old woman presenting with orthostatic tremor (OT) was reported. In addition to OT, neurological examination showed mild dementia, bradykinesia, rigidity of the neck and the upper limbs and positive Babinski reflex on the left. These clinical signs and CT as well as MRI findings suggested vascular parkinsonism as its pathological background. Upon standing with her feet together, she rapidly developed rhythmic repetitive contraction of all leg muscles. The shaking disappeared by walking, sitting, or lying down. The EMG recording revealed 4-Hz tremor which consisted of alternating contraction of anti-gravity muscles and their antagonists. The EMG bursts associated with the tremor were synchronous in corresponding muscles of both legs. OT could be bilaterally reset by unilateral voluntary or passive movement of leg. In the supine position, the tremor was not evoked by voluntary contraction of leg muscles against resistance. As the tremor was aggravated by the administration of haloperidol was suppressed by L-DOPA, it was thought to have the pharmacological basis common to the resting tremor of parkinsonism. Furthermore, we postulated that the postural tonus-regulating system, which is thought to set and maintain the tonus of antigravity muscles for standing upright, might be involved in the generation of the rhythmic discharge pattern (reciprocal bursts in a given leg and synchronized bursts in both legs) of OT.     

Gabapentin can improve postural stability and quality of life in primary orthostatic tremor.

Primary orthostatic tremor (OT) is characterized by leg tremor and instability on standing. High frequency (13-18 Hz) tremor bursting is present in leg muscles during stance, and posturography has shown greater than normal sway. We report on an open-label add-on study of gabapentin in 6 patients with OT. Six patients were studied with surface electromyography, force platform posturography, and a modified Parkinson's disease questionnaire (PDQ-39) quality of life (QOL) scale before and during treatment with gabapentin 300 mg t.d.s. If on other medications for OT, these were continued unchanged. Of the 6 patients, 4 reported a subjective benefit of 50 to 75% with gabapentin, 3 of whom showed reduced tremor amplitude and postural sway of up to 70%. Dynamic balance improved in all 3 patients who completed the protocol. QOL data from 5 patients showed improvement in all cases. No adverse effects were noted. Gabapentin may improve tremor, stability, and QOL in patients with OT, and symptomatic response correlated with a reduction in tremor amplitude and postural sway. The findings confirm previous reports of symptomatic benefit with gabapentin and provide justification for larger controlled clinical trials. Further work is required to establish the optimal dosage and to validate the methods used to quantify the response to treatment.     

Proprioceptive muscle tendon stimulation reduces symptoms in primary orthostatic tremor

Introduction

Primary orthostatic tremor (OT) is characterized by high-frequency lower limb muscle contractions and a disabling sense of unsteadiness while standing. To date, therapeutic options for OT are limited. Here, we examined the effects of proprioceptive leg muscle stimulation via muscle tendon vibration (MTV) on tremor and balance control in patients with primary OT.

Methods

Tremor in nine patients with primary OT was examined during four conditions: standing (1), standing with MTV on the bilateral soleus muscles (2), lying (3), and lying with MTV (4). Tremor characteristics were assessed by frequency domain analysis of surface EMG recordings from four leg muscles. Body sway was analyzed using posturographic recordings.

Results

During standing, all patients showed a coherent high-frequency tremor in leg muscles and body sway that was absent during lying (p?<?0.001). MTV during standing did not reset tremor frequency, but resulted in a decreased tremor intensity (p?<?0.001; mean reduction: 32.5?±?7.1%) and body sway (p?=?0.032; mean reduction: 37.2?±?6.8%). MTV did not affect muscle activity during lying. Four patients further reported a noticeable relief from unsteadiness during stimulation.

Conclusion

Proprioceptive stimulation did not reset tremor frequency consistent with the presumed central origin of OT. However, continuous MTV influenced the emergence of OT symptoms resulting in reduced tremor intensity, improved posture, and a relief from unsteadiness in half of the examined patients. These findings indicate that MTV either directly interferes with the peripheral manifestation of the central oscillatory pattern or prevents proprioceptive afferent feedback from becoming extensively synchronized at the tremor frequency.

     

Two cases with postural axial tremor: Consider a genetic origin

We present two cases with postural axial tremor predominantly involving the head, trunk, and shoulders. In the first patient, the postural tremor occurred in multiple attacks a day lasting approximately 10 min. The second patient developed a progressive tremor of his head and arms, worsened during sitting and standing. Electrophysiological supported the postural axial tremor in both patients with a varying 3–10 Hz tremor frequency between different muscles and within the same muscles at different times.Postural axial tremor is a rare and complex movement disorder. The majority of cases are caused by acquired cerebellar pathology. However, isolated cases with underlying genetic disorders are described in literature.Here, we illustrate how to differentiate paroxysmal axial tremor from other axial hyperkinetic movement disorders and extend the genetic heterogeneity of this intriguing movement disorder phenotype.     

Orthostatic tremor: essential and symptomatic cases

We studied clinically and electrophysiologically 8 patients affected by orthostatic tremor (OT), which is an unusual movement disorder consisting of shaking movements of the legs and trunk in the standing position. We failed to find any cause in 6 of the 8 cases. In 2 patients OT was clearly secondary to neurologic disease: hydrocephalus due to non-tumoral aqueduct stenosis and chronic relapsing polyradiculoneuropathy. The findings obtained suggest a relationship between OT and essential tremor (ET).     

Familial orthostatic tremor and essential tremor in two young brothers: A rare entity

Orthostatic tremor (OT), is usually a disease of old age and is characterized by quivering movements of the legs during quiet standing or in the state of isometric contraction in the lower limbs. This is relieved on walking or on lying down. It is diagnosed by surface electromyography, particularly over the quadriceps femoris muscles which shows a distinctive frequency of 13 to 18 Hz on standing. Some investigators consider it as a variant of essential tremor (ET) and the two conditions often co-exist. The disease is usually non-familial. Two brothers presented with tremor in the lower limbs on standing and on the outstretched hands without any family history. Subsequently, they were proved to be suffering from OT and ET by clinical examination and surface EMG. Simultaneous occurrence of OT and ET in two young brothers without any family history in the previous generation has not been described before and they also appeared at a much earlier age than what is described in the literature.     

Deep brain stimulation of the ventral intermediate nucleus of the thalamus in medically refractory orthostatic tremor: Preliminary observations

Orthostatic tremor (OT) is a disabling movement disorder associated with postural and gait impairment in the elderly. Medical therapy often yields insufficient benefit. We report the clinical and electrophysiological data on two patients with medication‐refractory OT treated with deep brain stimulation of the ventral intermediate thalamic nucleus (Vim DBS). Patient 1 underwent bilateral deep brain stimulation (DBS) and Patient 2 unilateral Vim DBS following 28 and 30 years of disease duration, respectively. Both patients showed increased latency to symptom onset after rising from a seated position, improved tolerance for prolonged standing, and slower crescendo of tremor severity when remaining upright. Postoperative evaluation demonstrated decreased amplitude of electromyographic activity with persistence of well‐defined oscillatory behavior showing strong coherence at 15 Hz between all muscles tested in the upper and lower limbs. Postural sway was unchanged. Clinical benefits have been sustained for over 18 months in Patient 1, and receded after 3 months in Patient 2. These findings support the consideration of bilateral Vim DBS implantation as a therapeutic option in patients with medically refractory OT. Further efficacy studies on chronic stimulation to disrupt the abnormal oscillatory activity in this disorder are warranted. © 2008 Movement Disorder Society     

Orthostatic tremor in progressive supranuclear palsy.

Patients with orthostatic tremor (OT) can be classified as having "primary OT," with or without postural arm tremor but no other abnormal neurological features, or "OT plus." We describe a patient with OT, with postural tremor of the arms and restless legs syndrome (RLS), who developed features typical of progressive supranuclear palsy (PSP). PSP can be accompanied by OT.     

Primary orthostatic tremor: further observations in six cases

Summary The clinical and physiological features of six new patients with primary orthostatic tremor are described. We suggest that use of the term primary orthostatic tremor be confined to the clinical syndrome in which unsteadiness when standing is the predominant complaint and accompanied by characteristic electrophysiological findings of a rapid (frequency around 16 Hz), regular leg tremor which is not influenced by peripheral feedback, is synchronous between homologous leg muscles, and in certain postures of the upper limbs, between muscles of the arm and leg. The fast frequency of muscle activity in primary orthostatic tremor of the legs causes unsteadiness when standing (presumably due to partially fused muscle contraction) but only a fine ripple of muscle activity is visible. In contrast, the slower frequency of other leg tremors, for example essential tremor, results in obvious leg movement which is evident in many leg postures, is variable over time and can be reset by a peripheral nerve stimulus. Essential tremor and orthostatic tremor do not respond to the same therapies, suggesting differences in the pharmacological profiles of the two conditions. Accordingly, there are clinical, physiological and pharmacological differences between primary orthostatic and essential tremor. Whether these factors are sufficient to regard these tremors as separate conditions is discussed.     

Clinical and neurophysiologic spectrum of orthostatic tremor: case series of 26 subjects.

Orthostatic tremor (OT) is a condition described as high-frequency tremors predominantly in the legs and trunk, which are present not only in the standing position but also during isometric contraction of the limb muscles. This report is one of the largest OT series describing clinical and neurophysiologic findings in 26 subjects with OT. The main findings included 13.0 to 18.6 Hz leg tremors while standing with varied patterns of phase relationships between the antagonists of the ipsilateral leg and between the homologous muscles of the contralateral leg, short latency tremor onset upon standing with abrupt cessation after sitting, coexistence of tremors in the cranial structures and the arms, and sense of unsteadiness without actual falls. Although the oscillator of OT is most likely located in the brainstem, cerebral cortex, basal ganglia, and cerebellum may also be involved in its pathogenesis.     

Natural history and syndromic associations of orthostatic tremor: a review of 41 patients.

Orthostatic tremor (OT) is a rare condition characterized by unsteadiness when standing still that is relieved when sitting or walking and is thought to arise from a central generator in the cerebellum or brainstem. OT is considered to be a distinct, discrete condition, and little is known about its demographic characteristics, natural history, associated features, and treatment response. We have reviewed these aspects in 41 OT patients fulfilling current diagnostic criteria, seen at our institution between 1986 and 2001. We classified 31 (75%) as having idiopathic "primary OT" either with (n = 24) or without an associated postural arm tremor. We found that 10 of 41 (25%) cases had additional neurological features, and we defined this group as having "OT plus" syndrome. Of these 10, 6 had parkinsonism; 4 of these had typical Parkinson's disease (PD), 1 had vascular and 1 had drug-induced parkinsonism. Among the remaining 4 patients, 2 had restless legs syndrome (RLS), 1 had tardive dyskinesia, and 1 orofacial dyskinesias of uncertain etiology. One patient with PD and the patient with vascular parkinsonism also had RLS. Age at onset was significantly earlier in the "primary OT" (mean +/- SD, 50.4 +/- 15.1) than in the "OT plus" (61.8 +/- 6.4; z = 2.7; P =.006) group. In 7 of the 10 "OT plus" patients, OT leg symptoms preceded the onset of additional neurological features. OT appeared to be underdiagnosed, and on average, it took 5.7 years from the initial complaints until a diagnosis was made. In general, treatment response to a variety of drugs such as clonazepam, primidone, and levodopa was poor. In most cases, OT symptoms remain relatively unchanged over the years, but in 6 of 41 cases (15%), the condition gradually worsened over the years, and in some of these cases, symptoms spread proximally to involve the trunk and arms. OT may not be a discrete disorder as commonly believed and associated features like parkinsonism present in nearly 25% of cases. Dopaminergic dysfunction may have a role in the pathophysiology of this disorder.     

Orthostatic tremor: an essential tremor variant?

Three patients with a clear-cut history of essential tremor of the upper limbs presented with the clinical features reported by Heilman as orthostatic tremor. Electromyographic findings included 6-8 Hz postural tremor in all four limbs. Highly synchronized 16 Hz rhythmic discharges were found in the legs upon standing. This peculiar pattern of discharge was also observed in the upper limbs and spinal muscles. High frequency rhythmic bursts, either alternating or co-contracting were present in specific postures not necessarily related to standing. An additional group of 12 patients with postural tremor of the legs was studied; seven of these showed modification in the frequency and synchronization of the muscle discharges upon standing. Although none of them had the full-blown clinical syndrome of orthostatic tremor, they complained of mild unsteadiness upon standing, together with a vague sensation of stiffness in the lower limbs. The present findings induce us to think that there might be a link between essential tremor and the so-called orthostatic tremor. Orthostatic tremor might be an essential-tremor-related entity that may be caused by a derangement in the central mechanism in charge of the organization of certain motor activities, not necessarily controlling the standing position.     

Impact of different stimulation types on orthostatic tremor.

OBJECTIVE: Primary orthostatic tremor (OT) is thought to be generated by a unique supraspinal tremor generator. Here we studied the effect of ipsi- and contralateral stimulation of the central and peripheral nervous system on OT. METHODS: In 7 patients with primary OT, surface EMG was recorded from both tibialis anterior muscles. We performed transcranial magnetic stimulation (TMS) over the vertex, and lumbar magnetic stimulation (LMS) over the lumbar spine. Supramaximal electrical nerve stimuli were applied to the tibial or peroneal nerve at the knee. Proprioceptive input was evoked by rhythmical submaximal stimulation of the tibial, peroneal or sural nerve at the ankle. RESULTS: TMS reset OT significantly in the contralateral as well as the ipsilateral tibialis anterior muscle. The resetting in both muscles was identical. In contrast, peripheral input by means of LMS, supra- or submaximal nerve stimulation had no impact on OT. CONCLUSIONS: Transcranial magnetic stimulation of one cortical leg area resets OT in both legs whereas OT is not modified by any peripheral stimuli applied in this study. SIGNIFICANCE: Our results support the hypothesis of n unique supraspinal OT generator. This generator receives a modulating input from the motor cortex.     

Orthostatic tremor: report of two cases and an electrophysiological study

Two patients with legs tremor present on standing, but none on walking or sitting, are reported. Tremor was not exclusive or orthostatism and was also evoked by strong tonic contraction of leg muscles. Synchronous EMG bursts were recorded in antagonistic muscle groups at 8-10 Hz in the first patient and at 16 Hz in the second. EMG activity was synchronous in corresponding muscles of both legs. The occurrence of EMG activity was not influenced by stimulation of nerve afferent fibers. We suggest that this movement disorder may be an exaggeration of physiological tremor due to synchronization of motor units by spontaneous oscillations in central structures.     

Isometric features of orthostatic tremor: an electromyographic analysis

A patient is described with "orthostatic" tremor. Electromyography revealed tremor bursts of 15 Hz in the lower extremities while standing and with isometric activation of the muscles, but the bursts disappeared with isotonic activation of muscles. Similar tremor was recorded in the arms with isometric, but not isotonic activation. Review of previously reported cases confirms these findings. The clinical and electrophysiologic features of this tremor distinguish it from other recognized forms of tremor.     

Myoclonus or tremor in orthostatism: an under-recognized cause of unsteadiness in Parkinson's disease.

Patients with Parkinson's disease (PD) often complain of unsteadiness. This can occur as the result of various neurological dysfunctions, including changes in postural adjustments, loss of postural reflexes, axial akinesia and rigidity, freezing and/or postural hypotension. In some cases these symptoms remain unexplained, and rare cases of unsteadiness have been attributed to tremor on standing. To delineate this condition, we investigated 11 consecutive PD patients with unexplained unsteadiness because of tremor on standing, seen in our department over a 6-year period. All the patients had detailed clinical and electrophysiological investigations based on surface polygraphic electromyographic recordings. Four patients had fast orthostatic tremor (13-18 Hz), one had intermediate orthostatic tremor (8-9 Hz), and three had slow orthostatic tremor (4-6 Hz). The remaining 3 patients had orthostatic myoclonus, a condition that has not previously been reported in PD. Patients with fast tremor improved on clonazepam. Patients with slow tremor and myoclonus improved on levodopa and sometimes benefited further when clonazepam was added. These observations show the usefulness of neurophysiological investigations for diagnosing and treating unexplained unsteadiness in Parkinson's disease.     

"Orthostatic tremor' in familial-essential tremor

We studied a family with essential tremor of the arms. Some members also had tremor of the trunk and legs on standing, but not on walking, sitting, or reclining. Tremor was evoked, regardless of body or limb position, by strong tonic contraction of the appropriate muscles; it was a type of static postural tremor. Beta-adrenergic blockers had no effect on the tremor of the trunk or legs, but clonazepam was beneficial.     

Primary orthostatic tremor is an exaggeration of a physiological response to instability.

Primary orthostatic tremor (POT) is a rare disorder characterised by an intense sense of unsteadiness upon standing and a 16-Hz tremor in which the timing between tremor bursts in different muscles (unilateral and bilateral) remains constant. Hitherto, similar EMG activity has not been described in healthy subjects and it has been postulated that the oscillations seen in POT are primarily pathological. In this study, EMG was recorded from tibialis anterior in healthy subjects who were made unsteady through vestibular galvanic stimulation or leaning backwards. Under these conditions, a peak at approximately 16 Hz was seen in the coherence between the left and right tibialis anterior. This bilateral coherence was absent when the subjects activated the same muscles when not unsteady. These data indicate the existence of a physiological system involved in organising postural responses under circumstances of imbalance and characterised by a highly synchronised output at approximately 16 Hz. In addition, the results suggest that the core abnormality in POT may be an exaggerated sense of unsteadiness when standing still, which then elicits activity from a 16-Hz oscillator normally engaged in postural responses.     

The central oscillatory network of orthostatic tremor

Orthostatic tremor (OT) is a movement disorder of the legs and trunk that is present in the standing position but typically absent when sitting. The pathological central network involved in orthostatic tremor is still unknown. In this study we analyzed 15 patients with simultaneous high‐resolution electroencephalography and electromyography recording to assess corticomuscular coherence. In 1 patient we were able to simultaneously record the local field potential in the ventrolateral thalamus and electroencephalography. Dynamic imaging of coherent source analysis was used to find the sources in the brain that are coherent with the peripheral tremor signal. When standing, the network for the tremor frequency consisted of unilateral activation in the primary motor leg area, supplementary motor area, primary sensory cortex, two prefrontal/premotor sources, thalamus, and cerebellum for the whole 30‐second segment recorded. The source coherence dynamics for the primary leg area and the thalamic source signals with the tibialis anterior muscle showed that they were highly coherent for the whole 30 seconds for the contralateral side but markedly decreased after 15 seconds for the ipsilateral side. The source signal and the recorded thalamus signal followed the same time frequency dynamics of coherence in 1 patient. The corticomuscular interaction in OT follows a consistent pattern with an initially bilateral pattern and then a segregated unilateral pattern after 15 seconds. This may add to the feeling of unsteadiness. It also makes the thalamus unlikely as the main source of orthostatic tremor. © 2013 International Parkinson and Movement Disorder Society     

Blinded placebo crossover study of gabapentin in primary orthostatic tremor.

Primary orthostatic tremor (OT) is a rare but disabling condition characterized by leg tremor and feelings of instability during stance. Previous studies have reported a reduction in OT symptoms with gabapentin treatment. In this study, we report on the benefits of gabapentin treatment in a double-blind placebo-controlled crossover study of 6 OT patients. First, the maximally effective gabapentin dosage (600-2,700 mg/day) for each patient was determined during an initial dose-titration phase. Patients were then studied 7 days after drug withdrawal and again after two 2-week periods of treatment with either gabapentin or placebo, using force platform posturography to quantify postural sway and tremor. Other medications for OT were continued unchanged. Symptomatic response was assessed by a patient-rated severity scale and quality of life (QOL) questionnaire. All patients reported an increase in symptoms during the washout phase and symptom reduction (50%-75%) during gabapentin treatment. Tremor amplitude was reduced to 79% +/- 11% and sway area to 71% +/- 11% of the placebo state. QOL improved in all patients, no adverse drug effects were noted, and symptomatic benefit was maintained at follow-up (mean = 19 months). The findings confirm that gabapentin is an effective treatment for OT, reducing both tremor and postural instability and improving quality of life, and support its use as add-on or first-line therapy for OT.