A lesion of the anterior thalamus producing dystonic tremor of the hand

Deep Brain Stimulation of the Caudal Zona Incerta and Motor Thalamus for Postischemic Dystonic Tremor of the Left Upper Limb: Case Report and Review of the Literature

BACKGROUND

Dystonic tremor is defined as a tremor occurring in a body region affected by dystonia. The pathophysiologic mechanisms behind dystonic tremor supposedly involve anomalies affecting the pallidothalamic-receiving area (for the dystonic component) and the ventralis intermedius-cortical loop (for the tremor component). Interest in posterior subthalamic area stimulation for various types of involuntary abnormal movements has arisen owing to positive results in patients affected by tremor refractory to ventralis intermedius deep brain stimulation.

CASE DESCRIPTION

A 23-year-old man, with a 15-year history of left upper limb dystonic tremor due to a stroke in the right thalamus, underwent deep brain stimulation with a single electrode passing through the right ventralis oralis anterior/ventralis oralis posterior nuclei and caudal zona incerta. Objective movement outcomes were assessed through the Unified Dystonia Rating Scale and Fahn-Tolosa-Marin Clinical Rating Scale for Tremor. The impact of tremor on activities of daily living was assessed with the ADL-T24 questionnaire, and quality of life was assessed with the Quality of Life Scale. All questionnaires were administered before deep brain stimulation and at 5-year follow-up. Unified Dystonia Rating Scale and Fahn-Tolosa-Marin Clinical Rating Scale for Tremor scores decreased from 14.5 to 4.5 and from 46 to 7, respectively. ADL-T24 score decreased from 19 to 3, whereas Quality of Life Scale score increased from 49 to 82.

CONCLUSIONS

Stimulation of motor thalamus and caudal zona incerta could be a viable treatment for patients affected by tremor of various origins, including dystonic tremor, refractory to medical therapy.

Holmes Tremor Partially Responsive to Topiramate: A Case Report

Background

Holmes tremor is a rare symptomatic movement disorder, characterized by a combination of resting, postural, and intention tremor. It is usually caused by lesions in the brainstem, thalamus, and cerebellum. Despite pharmacological advances, its treatment remains a challenge; many medications have been used with various degrees of effectiveness. Stereotactic thalamotomy and deep brain stimulation in the ventralis intermedius nucleus have been effective surgical procedures in cases refractory to medical treatment.

Case Report

Here we report a young woman with topiramate-responsive Holmes tremor secondary to a brainstem cavernoma.

Discussion

Herein we report a Holmes tremor responsive to Topiramate.

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.

Movement Disorders Following Cerebrovascular Lesion in the Basal Ganglia Circuit

Movement disorders are primarily associated with the basal ganglia and the thalamus; therefore, movement disorders are more frequently manifest after stroke compared with neurological injuries associated with other structures of the brain. Overall clinical features, such as types of movement disorder, the time of onset and prognosis, are similar with movement disorders after stroke in other structures. Dystonia and chorea are commonly occurring post-stroke movement disorders in basal ganglia circuit, and these disorders rarely present with tremor. Rarer movement disorders, including tic, restless leg syndrome, and blepharospasm, can also develop following a stroke. Although the precise mechanisms underlying the pathogenesis of these conditions have not been fully characterized, disruptions in the crosstalk between the inhibitory and excitatory circuits resulting from vascular insult are proposed to be the underlying cause. The GABA (gamma-aminobutyric acid)ergic and dopaminergic systems play key roles in post-stroke movement disorders. This review summarizes movement disorders induced by basal ganglia and thalamic stroke according to the anatomical regions in which they manifest.

The anatomical basis of upper limb dystonia: lesson from secondary cases

Upper limb dystonia is a focal dystonia that may affect muscles in the arm, forearm and hand. The neuroanatomical substrates involved in upper limb dystonia are not fully understood. Traditionally, dysfunction of the basal ganglia is presumed to be the main cause of dystonia but a growing body of evidence suggests that a network of additional cortical and subcortical structures may be involved. To identify the brain regions that are affected in secondary upper limb dystonia may help to better understand the neuroanatomical basis of the condition. We considered only patients with focal upper limb dystonia associated with a single localized brain lesion. To identify these patients, we conducted a systematic review of the published literature as well as the medical records of 350 patients with adult-onset dystonia seen over past 15 years at our movement disorder clinic. The literature review revealed 36 articles describing 72 cases of focal upper limb dystonia associated with focal lesions. Among patients at our clinic, four had focal lesions on imaging studies. Lesions were found in multiple regions including thalamus (n = 39), basal ganglia (n = 17), cortex (n = 4), brainstem (n = 4), cerebellum (n = 1), and cervical spine (n = 7). Dystonic tremor was not associated with any particular site of lesion, whereas there was a trend for an inverse association between task specificity and thalamic involvement. These data in combination with functional imaging studies of idiopathic upper limb dystonia support a model in which a network of different regions plays a role in pathogenesis.

Arm Posturing in a Patient Following Stroke: Dystonia, Levitation, Synkinesis, or Spasticity?

BACKGROUND

Post-stroke movement disorders occur in up to 4% of stroke patients. The movements can be complex and difficult to classify, which presents challenges when attempting to understand the clinical phenomenology and provide appropriate treatment.

CASE REPORT

We present a 64-year-old male with an unusual movement in the arm contralateral to his ischemic stroke. The primary feature of the movement was an involuntary elevation of the arm, occurring only when he was walking.

DISCUSSION

The differential diagnosis includes dystonia, spontaneous arm levitation, synkinesis, and spasticity. We discuss each of these diagnostic possibilities in detail.

Thalamic involvement in paroxysmal kinesigenic dyskinesia: a combined structural and diffusion tensor MRI analysis

Alteration of basal ganglia-thalamocortical circuit has been hypothesized to play a role in the pathophysiology underlying paroxysmal kinesigenic dyskinesia (PKD). We investigated macrostructural and microstructural changes in PKD patients using structural and diffusion tensor magnetic resonance imaging (MRI) analyses. Twenty-five patients with idiopathic PKD and 25 control subjects were prospectively studied on a 3T magnetic resonance (MR) scanner. Cortical thickness analysis was used to evaluate cortical gray matter (GM) changes, and automated volumetry and shape analysis were used to assess volume changes and shape deformation of the subcortical GM structures, respectively. Tract-based spatial statistics (TBSS) was used to evaluate white matter integrity changes in a whole-brain manner, and region-of-interest (ROI) analysis of diffusion tensor metrics was performed in subcortical GM structures. Compared to controls, PKD patients exhibited a reduction in volume of bilateral thalami and regional shape deformation mainly localized to the anterior and medial aspects of bilateral thalami. TBSS revealed an increase in fractional anisotropy (FA) of bilateral thalami and right anterior thalamic radiation in patients relative to controls. ROI analysis also showed an increase in FA of bilateral thalami in patients compared to controls. We have shown evidence for thalamic abnormalities of volume reduction, regional shape deformation, and increased FA in patients with PKD. Our novel findings of concomitant macrostructural and microstructural abnormalities in the thalamus lend further support to previous observations indicating causal relationship between a preferential lesion in the thalamus and development of PKD, thus providing neuroanatomical basis for the involvement of thalamus within the basal ganglia-thalamocortical pathway in PKD.

Neural network of primary focal dystonia by an anatomic likelihood estimation meta-analysis of gray matter abnormalities

BACKGROUND

Recent voxel-based morphometry (VBM) studies have found gray matter (GM) abnormalities in primary focal dystonia (PFD) and yielded inconsistent results.

AIM

Our aim is to investigate consistent GM changes in PFD and to identify whether different subtypes of PFD share a common pathophysiological basis revealed by structural abnormalities.

METHODS

A systematic search of VBM studies of patients with PFD and healthy control (HC) subjects published in PubMed, Embase, and Medline databases from January 1998 to April 2011 was conducted. We performed a voxel-wise meta-analysis of VBM studies comparing PFD to HC using the anatomic likelihood estimation (ALE) method.

RESULTS

A total of 9 articles, which reported 11 PFD-HC comparisons including 199 PFD patients and 247 HC subjects, met the inclusion criteria. GM volume (GMV) was found to be greater in the caudate, postcentral cortex (BA2, 3, 40) and primary motor cortex, and smaller in the thalamus and putamen.

CONCLUSION

Our findings provide evidence for structural abnormalities within the sensorimotor network involved in the pathophysiology of PFD. However, our work could not distinguish whether the brain structural changes are primary or secondary to PFD.

The functional neuroanatomy of dystonia

Dystonia is a neurological disorder characterized by involuntary twisting movements and postures. There are many different clinical manifestations, and many different causes. The neuroanatomical substrates for dystonia are only partly understood. Although the traditional view localizes dystonia to basal ganglia circuits, there is increasing recognition that this view is inadequate for accommodating a substantial portion of available clinical and experimental evidence. A model in which several brain regions play a role in a network better accommodates the evidence. This network model accommodates neuropathological and neuroimaging evidence that dystonia may be associated with abnormalities in multiple different brain regions. It also accommodates animal studies showing that dystonic movements arise with manipulations of different brain regions. It is consistent with neurophysiological evidence suggesting defects in neural inhibitory processes, sensorimotor integration, and maladaptive plasticity. Finally, it may explain neurosurgical experience showing that targeting the basal ganglia is effective only for certain subpopulations of dystonia. Most importantly, the network model provides many new and testable hypotheses with direct relevance for new treatment strategies that go beyond the basal ganglia. This article is part of a Special Issue entitled "Advances in dystonia".

Role of neuroimaging in the evaluation of tremor

The role for neuroimaging in the management of patients with tremor is gradually increasing, particularly with respect to stereotactic neurosurgery and deep brain stimulation where less than 2-mm tolerance is required for accurate electrode placement. The routine use of single photon emission CT technology to image the nigrostriatal dopaminergic system is proving helpful in distinguishing essential and dystonic tremors from neurodegenerative forms of parkinsonism and in improving our understanding of the pathophysiology of rarer tremors.

Paroxysmal sleep as a presenting symptom of bilateral paramedian thalamic infarctions

Bilateral paramedian thalamic infarctions may result in hypersomnolence, supranuclear palsy, and an amnestic syndrome. We describe an 82-year-old man who presented with recurrent, transient episodes of unresponsiveness secondary to bilateral paramedian thalamic infarctions. Electroencephalography was performed during one of these paroxysmal events and showed an abrupt transition to a stage 2 sleep pattern with spindle formation.