"Rubral" tremor after thalamic haemorrhage

Deep brain stimulation of the ventralis intermedius nucleus of the thalamus and posterior subthalamic area for Holmes' tremor secondary to brainstem hemorrhage: A case report

Holmes' tremor is a rare but severely disabling movement disorder characterized by a combination of resting, action, and intention tremor. Because Holmes' tremor is usually resistant to pharmacotherapy, surgical treatment is required for symptom control in most cases. We report the case of a 56-year-old man who was diagnosed with Holmes' tremor and treated with stimulation of the ventralis intermedius nucleus of the thalamus and posterior subthalamic area. Deep brain stimulation alleviated the patient's tremor over a 3-year follow-up period.

Post-Thalamic Stroke Movement Disorders: A Systematic Review

BACKGROUND

After a stroke, movement disorders are rare manifestations mainly affecting the deep structures of the brain like the basal ganglia (44%) and thalamus (37%), although there have been case studies of movement disorders in strokes affecting the cerebral cortex also.

SUMMARY

This review aims to delineate the various movement disorders seen in association with thalamic strokes and tries to identify the location of the nuclei affected in each of the described movement disorders. Cases were identified through a search of PubMed database using different search terms related to post-thalamic stroke movement disorders and a secondary search of references of identified articles. We reviewed 2,520 research articles and only 86 papers met the inclusion criteria. Cases were included if they met criteria for post-thalamic stroke movement disorders. Case-cohort studies were also reviewed and will be discussed further. Key Messages: The most common post-stroke abnormal movement disorder reported in our review was dystonia followed by hemiataxia. There was a higher association between ischaemic stroke and movement disorder. Acute onset movement disorders were more common than delayed. The posterolateral thalamus was most commonly involved in post-thalamic stroke movement disorders.

Tremor Secondary to a Thalamic Glioma: A Case Report

BACKGROUND AND IMPORTANCE

Tremor is the most prevalent movement disorder. While the exact pathophysiology remains to be elucidated, the importance of the thalamus in tremor circuitry is well recognized. Thalamic lesions from demyelination, trauma, ischemia, or neoplasm rarely cause isolated tremor. We report the case of a patient presenting with a tremor secondary to a thalamic grade II astrocytoma that improved with treatment.

CLINICAL PRESENTATION

A 50-yr-old male presented with a 1-yr history of right-hand tremor. The presence of long tract signs prompted imaging that revealed a lesion within the left thalamus. Stereotactic biopsy revealed a World Health Organization grade II astrocytoma. Prior to biopsy, the patient's tremor was graded using the Clinical Rating Scale for Tremor. Immediately postoperatively the patient remained at his neurological baseline without improvement in his tremor. Subsequent fractionated radiotherapy with concomitant temozolomide followed by adjuvant temozolomide led to radiographic response as well as clinical improvement. The patient reported less tremor, which was confirmed objectively with improved Clinical Rating Scale for Tremor scores at 6 and 12 mo postoperatively.

CONCLUSION

This case of a thalamic glioma presenting with isolated contralateral tremor highlights the role of the thalamus in the development of tremor. Moreover, this particular case contrasts with other published reports on the lack of additional symptoms and tremor response to chemoradiation.

Holmes tremor: Clinical description, lesion localization, and treatment in a series of 29 cases

OBJECTIVE

To describe the clinical features, etiology, findings from neuroimaging, and treatment results in a series of 29 patients with Holmes tremor (HT).

METHODS

A retrospective study was performed based on review of medical records and videos of patients with HT diagnosis.

RESULTS

A total of 16 women and 13 men were included. The mean age at the moment of CNS insult was 33.9 ± 20.1 years (range 8-76 years). The most common causes were vascular (48.3%), ischemic, or hemorrhagic. Traumatic brain injury only represented 17.24%; other causes represented 34.5%. The median latency from lesion to tremor onset was 2 months (range 7 days-228 months). The most common symptoms/signs associated with HT were hemiparesis (62%), ataxia (51.7%), hypoesthesia (27.58%), dystonia (24.1%), cranial nerve involvement (24.1%), and dysarthria (24.1%). Other symptoms/signs were vertical gaze disorders (6.8%), bradykinesia/rigidity (6.8%), myoclonus (3.4%), and seizures (3.4%). Most of the patients had lesions involving more than one area. MRI showed lesions in thalamus or midbrain or cerebellum in 82.7% of the patients. Levodopa treatment was effective in 13 out of 24 treated patients (54.16%) and in 3 patients unilateral thalamotomy provided excellent results.

CONCLUSIONS

The most common causes of HT in our series were vascular lesions. The most common lesion topography was mesencephalic, thalamic, or both. Treatment with levodopa and thalamic stereotactic lesional surgery seems to be effective.

Holmes tremor: Clinical description, lesion localization, and treatment in a series of 29 cases

OBJECTIVE

To describe the clinical features, etiology, findings from neuroimaging, and treatment results in a series of 29 patients with Holmes tremor (HT).

METHODS

A retrospective study was performed based on review of medical records and videos of patients with HT diagnosis.

RESULTS

A total of 16 women and 13 men were included. The mean age at the moment of CNS insult was 33.9 ± 20.1 years (range 8-76 years). The most common causes were vascular (48.3%), ischemic, or hemorrhagic. Traumatic brain injury only represented 17.24%; other causes represented 34.5%. The median latency from lesion to tremor onset was 2 months (range 7 days-228 months). The most common symptoms/signs associated with HT were hemiparesis (62%), ataxia (51.7%), hypoesthesia (27.58%), dystonia (24.1%), cranial nerve involvement (24.1%), and dysarthria (24.1%). Other symptoms/signs were vertical gaze disorders (6.8%), bradykinesia/rigidity (6.8%), myoclonus (3.4%), and seizures (3.4%). Most of the patients had lesions involving more than one area. MRI showed lesions in thalamus or midbrain or cerebellum in 82.7% of the patients. Levodopa treatment was effective in 13 out of 24 treated patients (54.16%) and in 3 patients unilateral thalamotomy provided excellent results.

CONCLUSIONS

The most common causes of HT in our series were vascular lesions. The most common lesion topography was mesencephalic, thalamic, or both. Treatment with levodopa and thalamic stereotactic lesional surgery seems to be effective.

Holmes' tremor associated with bilateral hypertrophic olivary degeneration following brain stem hemorrhage: a case report

Holmes' tremor is a condition characterized by a mixture of postural, rest, and action tremors due to midbrain lesions in the vicinity of the red nucleus. Hypertrophic olivary degeneration (HOD) is a rare type of neuronal degeneration involving the dento-rubro-olivary pathway and may present clinically as Holmes tremor. We report on a 59-year-old female patient who developed Holmes tremor in association with bilateral HOD, following brain stem hemorrhage.

Dystonia and tremor secondary to a pediatric thalamic stroke

A previously healthy 10-year-old girl developed a right hemiparesis with sensory loss secondary to a posterolateral thalamic infarct. Despite improvement in strength, three weeks later a 4 Hz kinetic tremor appeared in the right hand accompanied by dystonia in the right upper and lower limbs. Basal ganglia vascular lesions are rare in childhood and movement disorders secondary to such lesions even more so. A thorough work-up failed to disclose the etiology. Our patient illustrates that dystonia and tremor secondary to posterolateral thalamic infarctions are also apt to occur in children and, unlike the adult picture, abnormal movements may develop very soon after the insult.

Cognitive, affective and behavioural disturbances following vascular thalamic lesions: a review

During the last decades, many studies have shown that the thalamus is crucially involved in language and cognition. We critically reviewed a study corpus of 465 patients with vascular thalamic lesions published in the literature since 1980. 42 out of 465 (9%) cases with isolated thalamic lesions allowed further neurocognitive analysis. On the neurolinguistic level, fluent output (=31/33; 93.9%), normal to mild impairment of repetition (=33/35; 94.3%), mild dysarthria (=8/9; 88.9%) and normal to mild impairment of auditory comprehension (=27/34; 79.4%) were most commonly found in the group of patients with left and bilateral thalamic lesions. The taxonomic label of thalamic aphasia applied to the majority of the patients with left thalamic damage (=7/11; 63.6%) and to one patient with bithalamic lesions (=1/1). On the neuropsychological level, almost 90% of the left thalamic and bithalamic patient group presented with amnestic problems, executive dysfunctions and behaviour and/or mood alterations. In addition, two thirds (2/3) of the patients with bilateral thalamic damage presented with a typical cluster of neurocognitive disturbances consisting of constructional apraxia, anosognosia, desorientation, global intellectual dysfunctioning, amnesia, and executive dysfunctions associated with behaviour and/or mood alterations. Our study supports the long-standing view of a 'lateralised linguistic thalamus' but restates the issue of a 'lateralised cognitive thalamus'. In addition, critical analysis of the available literature supports the view that aphasia following left or bithalamic damage constitutes a prototypical linguistic syndrome.

Thalamic tumour presenting with Holmes' tremor: diagnostic difficulties

The presentation of intracerebral tumours with tremor is rare. A case is described of a 78-year-old woman presenting with Holmes' tremor who was found to have a thalamic tumour. The diagnostic context of tumours that present with tremor is discussed along with the pathophysiology and management of this case.

Systemic diseases that cause movement disorders

The present review is aimed at providing practical assistance to the clinical neurologist in reaching a diagnosis, understanding the pathogenic mechanisms of movement disorders associated with systemic diseases, and determining appropriate therapy. Infectious disease by direct effect or as an acquired autoimmune neurological disease, stroke, hypoxia-ischemia, paraneoplastic syndromes, collagen disorders, endocrine, liver and kidney diseases that may cause hypokinetic or hyperkinetic abnormal movement are considered separately. The type and evolution of abnormal movement caused by systemic disease vary with age and underlying pathology. Therapy for abnormal movements should include a primary treatment for the systemic disease.

Post-stroke movement disorders: report of 56 patients

BACKGROUND

Although movement disorders that occur following a stroke have long been recognised in short series of patients, their frequency and clinical and imaging features have not been reported in large series of patients with stroke.

METHODS

We reviewed consecutive patients with involuntary abnormal movements (IAMs) following a stroke who were included in the Eugenio Espejo Hospital Stroke Registry and they were followed up for at least one year after the onset of the IAM. We determined the clinical features, topographical correlations, and pathophysiological implications of the IAMs.

RESULTS

Of 1500 patients with stroke 56 developed movement disorders up to one year after the stroke. Patients with chorea were older and the patients with dystonia were younger than the patients with other IAMs. In patients with isolated vascular lesions without IAMs, surface lesions prevailed but patients with deep vascular lesions showed a higher probability of developing abnormal movements. One year after onset of the IAMs, 12 patients (21.4%) completely improved their abnormal movements, 38 patients (67.8%) partially improved, four did not improve (7.1%), and two patients with chorea died. In the nested case-control analysis, the patients with IAMs displayed a higher frequency of deep lesions (63% v 33%; OR 3.38, 95% CI 1.64 to 6.99, p<0.001). Patients with deep haemorrhagic lesions showed a higher probability of developing IAMs (OR 4.8, 95% CI 0.8 to 36.6).

CONCLUSIONS

Chorea is the commonest movement disorder following stroke and appears in older patients. Involuntary movements tend to persist despite the functional recovery of motor deficit. Deep vascular lesions are more frequent in patients with movement disorders.

Deep brain stimulation of the nucleus ventralis intermedius for Holmes (rubral) tremor and associated dystonia caused by upper brainstem lesions

✓Holmes tremor is caused by structural lesions in the perirubral area of the midbrain. Patients often present with associated symptoms such as dystonia and paresis, which are usually refractory to medical therapy. Here, the authors describe two patients in whom both tremor and associated dystonia improved markedly following unilateral stimulation of the thalamic nucleus ventralis intermedius.

Approche chirurgicale d’un tremblement de Holmes associé à un tremblement synchrone de haute fréquence

INTRODUCTION

The effectiveness of thalamic stimulation is now clearly demonstrated for essential tremor, but remains to be demonstrated for other types of tremor.

OBSERVATION

A young woman presented Holmes' tremor resulting from a pontine tegmental hemorrhage related to an arteriovenous malformation. A surgical approach was considered when major functional impairment persisted at 2-year follow-up despite drug therapy. The patient underwent unilateral thalamic deep brain stimulation (Vim); major improvement persisted at eighteen months follow-up.

CONCLUSION

This observation is in line with previous reports suggesting that thalamic surgery can be one of the best options for treating medically intractable Holmes' tremor. The mechanism underlying the tremor, implying dentate-rubro-thalamic pathways is discussed. Moreover, the patient exhibited short periods of 16Hz tremor when her arms were maintained outstretched. Thalamic stimulation also appears to be effective for these high-frequency synchronous cerebellar bursts.

Deep brain stimulation of the nucleus ventralis intermedius for Holmes (rubral) tremor and associated dystonia caused by upper brainstem lesions. Report of two cases

Holmes tremor is caused by structural lesions in the perirubral area of the midbrain. Patients often present with associated symptoms such as dystonia and paresis, which are usually refractory to medical therapy. Here, the authors describe two patients in whom both tremor and associated dystonia improved markedly following unilateral stimulation of the thalamic nucleus ventralis intermedius.

Holmes tremor in association with bilateral hypertrophic olivary degeneration and palatal tremor: chronological considerations. Case report

Hypertrophic olivary degeneration (HOD) is a rare type of neuronal degeneration involving the dento-rubro-olivary pathway and presents clinically as palatal tremor. We present a 48 year old male patient who developed Holmes' tremor and bilateral HOD five months after brainstem hemorrhage. The severe rest tremor was refractory to pharmacotherapy and botulinum toxin injections, but was markedly reduced after thalamotomy. Magnetic resonance imaging permitted visualization of HOD, which appeared as a characteristic high signal intensity in the inferior olivary nuclei on T2- and proton-density-weighted images. Enlargement of the inferior olivary nuclei was also noted. Palatal tremor was absent in that moment and appears about two months later. The delayed-onset between insult and tremor following structural lesions of the brain suggest that compensatory or secondary changes in nervous system function must contribute to tremor genesis. The literature and imaging findings of this uncommon condition are reviewed.

Holmes' tremor following midbrain Toxoplasma abscess: clinical features and treatment of a case

The label Holmes' tremor defines a rare symptomatic movement disorder frequently occurring with midbrain damage. It appears at rest and worsens adopting a posture and on attempting movements. We describe the case of a patient with Holmes' tremor due to a presumed Toxoplasma abscess of the midbrain. The positive response to a combined therapy with levodopa and isoniazid is also reported.

Intracortical inhibition is reduced in a patient with a lesion in the posterolateral thalamus

We describe a patient who developed a complex movement disorder following an ischemic lesion in the right posterolateral thalamus. Transcranial magnetic stimulation showed a shortening of the cortical silent period and deficient cortico-cortical inhibition using paired magnetic pulses on the affected side, indicating reduced effectiveness of intracortical inhibitory mechanisms.

Rubral tremor after thalamic infarction in childhood

The occurrence of tremor after thalamic lesions is well known. Delayed rubral tremor secondary to bilateral thalamic infarction is a rare finding and has not been reported previously in childhood. We present two children with a combined resting-postural-kinetic tremor caused by bithalamic infarction. The first child was a male 14 months of age, and the second was a male 9 years of age. These children come from unrelated families. On hospital admission of the first patient, generalized seizures and routine electroencephalogram (EEG) findings with diffuse spike-wave discharges predominantly over the left frontal area were clinically observed, leading to the initial diagnosis of epilepsia partialis continua. However, clinical observation and video-EEG monitoring of the movements revealed nonepileptiform accompaniments, favoring the diagnosis of rubral tremor. In the second patient, EEG revealed no paroxysmal activity and was within normal limits for age. In both patients, cranial magnetic resonance imaging revealed ischemic lesions in thalami bilaterally but failed to reveal any mesencephalic lesion. These patients demonstrate that thalamic infarction can cause rubral tremor in childhood.

The pathophysiology of tremor

Tremor is defined as rhythmic oscillatory activity of body parts. Four physiological basic mechanisms for such oscillatory activity have been described: mechanical oscillations; oscillations based on reflexes; oscillations due to central neuronal pacemakers; and oscillations because of disturbed feedforward or feedback loops. New methodological approaches with animal models, positron emission tomography, and mathematical analysis of electromyographic and electroencephalographic signals have provided new insights into the mechanisms underlying specific forms of tremor. Physiological tremor is due to mechanical and central components. Psychogenic tremor is considered to depend on a clonus mechanism and is thus believed to be mediated by reflex mechanisms. Symptomatic palatal tremor is most likely due to rhythmic activity of the inferior olive, and there is much evidence that essential tremor is also generated within the olivocerebellar circuits. Orthostatic tremor is likely to originate in hitherto unidentified brainstem nuclei. Rest tremor of Parkinson's disease is probably generated in the basal ganglia loop, and dystonic tremor may also originate within the basal ganglia. Cerebellar tremor is at least in part caused by a disturbance of the cerebellar feedforward control of voluntary movements, and Holmes' tremor is due to the combination of the mechanisms producing parkinsonian and cerebellar tremor. Neuropathic tremor is believed to be caused by abnormally functioning reflex pathways and a wide variety of causes underlies toxic and drug-induced tremors. The understanding of the pathophysiology of tremor has made significant progress but many hypotheses are not yet based on sufficient data. Modern neurology needs to develop and test such hypotheses, because this is the only way to develop rational medical and surgical therapies.

Delayed onset mixed involuntary movements after thalamic stroke: clinical, radiological and pathophysiological findings

Although occurrence of involuntary movements after thalamic stroke has occasionally been reported, studies using a sufficiently large number of patients and a control population are not available. Between 1995 and 1999, the author prospectively identified 35 patients with post-thalamic stroke delayed-onset involuntary movements, which included all or some degree of dystonia-athetosis-chorea-action tremor, occasionally associated with jerky, myoclonic components. A control group included 58 patients examined by the author during the same period who had lateral thalamic stroke but no involuntary movements. Demography, clinical features and imaging study results were compared. There were no differences in gender, age, risk factors, side of the lesion and follow-up periods. During the acute stage of stroke, the patients who had involuntary movements significantly more often had severe (< or = III/V) hemiparesis (50 versus 20%, P < 0.05) and severe sensory loss (in all modalities, P < 0.01) than the control group. At the time of assessment of involuntary movements, the patients with involuntary movements significantly more often had severe sensory deficit (in all modalities, P < 0.01) and severe limb ataxia (60 versus 5%, P < 0.01) than the control patients, but neither more severe motor dysfunction (7 versus 0%) nor more painful sensory symptoms (57 versus 57%). The patients with involuntary movements had a higher frequency of haemorrhagic (versus ischaemic) stroke (63 versus 31%, P < 0.05). Further analysis showed that dystonia-athetosis-chorea was closely associated with position sensory loss, whereas the tremor/myoclonic movements were related to cerebellar ataxia. Recovery of severe limb weakness seemed to augment the instability of the involuntary movements. Persistent failure of the proprioceptive sensory and cerebellar inputs in addition to successful, but unbalanced, recovery of the motor dysfunction seemed to result in a pathological motor integrative system and consequent involuntary movements in patients with relatively severe lateral-posterior thalamic strokes simultaneously damaging the lemniscal sensory pathway, the cerebellar-rubrothalamic tract and, relatively less severely, the pyramidal tract.

Nonparkinsonian tremors

Tremors other than those associated with Parkinson's disease are commonly encountered in clinical practice. The differentiation of tremor subtypes depends primarily on the presence of distinct clinical characteristics and is facilitated by the use of consistent nomenclature. Such differentiation can be helpful in determining the etiology of the tremor and assist in its management. In this review, the authors outline recently proposed changes to classification and review the clinical features, differential diagnosis, and current therapy for nonparkinsonian tremors.

Thalamic tremor: correlations with three-dimensional magnetic resonance imaging data and pathophysiological mechanisms

Tremor associated with a single focal thalamic lesion has rarely been reported. Furthermore, the exact localization of the lesions is difficult to determine because of the imprecision of "conventional" radiology (computed tomography scan and/or "standard" magnetic resonance imaging). The aim of this study was to identify which thalamic structures are involved in tremor associated with a single focal thalamic lesion. We selected two patients who presented with unilateral postural and kinetic tremor of the upper limb related to a localized thalamic infarction. Three-dimensional T1-weighted magnetic resonance imaging sequence (MP-RAGE sequence) was used to determine the precise topography of the lesions by stereotactic analysis using the atlas of Hassler. The lesions were located within the pulvinar, the sensory nuclei, the mediodorsal nucleus, and the ventral lateral posterior nucleus (according to the classification of Hirai and Jones), the latter including the ventral intermediate nucleus (Vim according to the classification of Hassler). However, the Vim was spared. The subthalamic area, which can induce tremor, was not involved. After having compared the topography of the lesions with the clinical findings, we suggest that thalamic tremors may result from the interruption of the cerebellar outflow tract to the Vim within the thalamus.

123I-IPT brain SPECT study in essential tremor and Parkinson's disease

OBJECTIVE

To investigate nigral neuronal damage in patients with isolated postural tremor and those with postural and rest tremor without parkinsonism.

METHODS

Using [123I]-N-(3-iodopropen-2-yl)-2 -carbomethoxy-3beta-(4-chlorophenyl) tropane SPECT, we measured the basal ganglia-occipital cortex/occipital cortex ([BG-OCC]/OCC) uptake ratios in 21 control subjects and patients with isolated postural tremor (n = 9), postural and rest tremor (n = 6), and PD (n = 11).

RESULTS

In the patients with PD, the means (+/-SD) of the (BG-OCC)/OCC ratios of the ipsilateral (2.35+/-0.37) and the contralateral (1.97+/-0.33) sides to the more severely affected limbs were significantly lower than the mean of the bilateral (BG-OCC)/OCC ratios of the age-matched control subjects (3.83+/-0.66). The mean (+/-SD) of the bilateral (BG-OCC)/OCC ratios of the patients with isolated postural tremor (3.60+/-0.83) was comparable with that of the age-matched control subjects. However, the mean (+/-SD) of the bilateral (BG-OCC)/OCC ratios of the patients with postural and rest tremor (2.61+/-0.18) was lower than that of the control subjects (p < 0.05). The mean of the bilateral (BG-OCC)/OCC ratios of the patients with postural and rest tremor was comparable with that of the side ipsilateral to the severely affected limbs of the patients with PD. However, it was higher than that of the side contralateral to the limbs more severely affected by PD. Four of the six patients with postural and rest tremor had (BG-OCC)/OCC ratios lower than 2 standard deviations from the mean of the age-matched control subjects.

CONCLUSIONS

Later in their clinical courses, some patients with postural tremor may acquire rest tremor in association with mild substantia nigra neuronal loss.

Consensus statement of the Movement Disorder Society on Tremor. Ad Hoc Scientific Committee

This is a proposal of the Movement Disorder Society for a clinical classification of tremors. The classification is based on the distinction between rest, postural, simple kinetic, and intention tremor (tremor during target-directed movements). Additional data from a medical history and the results of a neurologic examination can be combined into one of the following clinical syndromes defined in this statement: enhanced physiologic tremor, classical essential tremor (ET), primary orthostatic tremor, task- and position-specific tremors, dystonic tremor, tremor in Parkinson's disease (PD), cerebellar tremor, Holmes' tremor, palatal tremor, drug-induced and toxic tremor, tremor in peripheral neuropathies, or psychogenic tremor. Conditions such as asterixis, epilepsia partialis continua, clonus, and rhythmic myoclonus can be misinterpreted as tremor. The features distinguishing these conditions from tremor are described. Controversial issues are outlined in a comment section for each item and thus reflect the open questions that at present cannot be answered on a scientific basis. We hope that this statement provides a basis for better communication among clinicians working in the field and stimulates tremor research.

Pathology of symptomatic tremors

Symptomatic tremors are labeled in the literature under different names including rubral tremor, midbrain tremor, thalamic tremor, myorhythmia, Holmes' tremor, cerebellar tremor, and goal-directed tremor. The most common tremor is a delayed-onset postural and action tremor with a low frequency of 3 Hz and a proximal distribution. Resting irregular tremor is sometimes present. Mild cerebellar dysmetria is often detected. The lesions are mainly located in the thalamus, the brain stem, and the cerebellum, with secondary interruption and degeneration of various pathways and olivary hypertrophy. The more consistent lesions are found in the cerebello-thalamo-cortical and dentato-rubro-olivary pathways. The role of superimposed dysfunction of the nigrostriatal system may account for the rest component. The role of the basal ganglia in the emergence and control of tremor is poorly understood.

Midbrain tremor and hypertrophic olivary degeneration after pontine hemorrhage

A severe rest tremor arose in a patient's right arm 9 months after a pontine tegmental hemorrhage. Magnetic resonance studies at 4 and 10 months showed residual hemosiderin in the pons and increasing hypertrophic olivary degeneration (HOD) affecting primarily the left olive. The tremor was refractory to pharmacotherapy (clonazepam, propranolol, and levodopa), but was reduced after implantation of a thalamic stimulator device. Although pontine hemorrhage is among several common causes of HOD, it has not previously been appreciated as a cause of midbrain ("rubral") tremor. A disynaptic dentatorubroolivary tract associated with tremor and monosynaptic dentatoolivary tract associated with HOD may both be components of the rubroolivocerebellorubral loop implicated in midbrain tremor. Their proximity makes the combination of tremor and HOD after pontine tegmental damage plausible and even likely.

Writer's cramp and tremor due to brain tumor

Writer's cramp is frequently associated with hand tremor and with other focal dystonias. Sometimes brain infarction, haemorrhage, arterio-venous malformations or tumors are found to cause symptomatic focal dystonias. A 44-year-old man came to our attention due to writer's cramp of his right hand and postural 6-8 Hz tremor. About three months after the onset of the disease the tremor and dystonia disappeared, while a right hemiparesis gradually appeared. Cranial computed tomography showed a hypodense nonhomogeneous lesion in the left cerebral hemisphere parietally, that was assumed to represent a cystic tumor. The patient underwent craniotomy and the histological diagnosis revealed an astrocytoma (Grade II-III). In conclusion our findings confirm the common anatomical basis of symptomatic focal dystonia and tremor. Both can appear after disruption of the pathways within and adjacent to the basal ganglia.