A 93-year-old female was brought to our emergency department due to acute-onset involuntary flinging movements in the left side which had started abruptly 6 h before admission. Medical history was unremarkable. On neurological examination, the patient was orientated and cooperated. However, involuntary movements of the proximal and distal muscles in both the extremities (prominently in the upper extremity) in the left side, which was compatible with hemiballismus, were recognized [Video 1]. Other evaluations including motor and sensorial examinations were in normal ranges. Cranial magnetic resonance imaging (MRI) revealed a small lacunar infarct in the right centrum semiovale (CS) [Figure 1]. Blood sample examinations yielded unremarkable findings (normal hemogram, kidney–liver functions, sedimentation, and glucose level). Taken together, the diagnosis of hemiballismus due to lacunar infarct in the CS was established. Aspirin 300 mg and atorvastatin therapies were initiated. Hemiballistic movements gradually were resolved spontaneously in the following 1-day period. Carotid and vertebral artery Doppler investigations revealed minor fibrocalcific plaques. Cardiac investigations were in normal ranges (echocardiography and electrocardiography). Ischemic stroke was explained in the setting of small-vessel disease, and the patient was discharged on aspirin 300 mg therapy with a normal neurological examination. However, 5 months later, the patient was readmitted to the emergency department due to sudden reemerging left-sided hemiballismus [Video 2]. On neurological examination at this admission, the patient was alert and cooperative, but she was not properly orientated that was compatible with a diagnosis of delirium. Laboratory examinations (hemogram, kidney–liver functions, sedimentation, and serum glucose) were in normal ranges. Cranial MRI showed multifocal bilateral patchy diffusion restriction in the bilateral subcortical white matter [Figure 2]. In the follow-up, due to anxious state and agitation, low-dose oral haloperidol was initiated which resulted in the recovery of symptoms as well as hemiballistic movements. On the 3rd day of hospitalization, the patient was totally recovered, and hemiballismus was completely resolved. She was discharged on dual antiplatelet therapy and donepezil treatment for newly diagnosed early-stage dementia.
Figure 1: Cranial magnetic resonance imaging showing restricted diffusion in the right centrum semiovale (arrows)
Hemiballismus can be defined as unilateral flinging movement of the limbs characterized by ballistic motion, a high-amplitude movement of an entire limb., Classically, it has been characterized as almost pathognomonic of a lesion in the contralateral subthalamic nucleus (STN). However, it can be caused in lesions outside the STN, and such that recent reports revealed that in only a minority of these cases, STN was directly involved.,, As various interconnections within the basal ganglia structures have been acknowledged, the accurate pathophysiology of hemiballismus as well as the impact of the disturbances in these basal ganglia structures in the development of hemiballismus and the role of processing other motor networks still remain to be elucidated. In our remarkable patient, the first clinical presentation of hemiballismus was found to be associated with acute infarct in the CS. However, more interestingly, the patient was the second time admitted with the same clinic, at which the MRI showed multifocal, patchy, subcortical-restricted diffusion focuses at this time. I think that the illustration of this case may give substantial perspectives regarding the underlying mechanisms of hemiballismus.
The classic knowledge, associating the dysfunction of STN with hemiballismus, emphasizes the interruption of excitatory input from the STN to the globus pallidus (GPi) (disrupting the indirect pathway) as the major mechanism of hemiballismus. However, there are still many limitations of this model to explain the pathophysiology of hemiballismus. For instance, previous reports showed that therapeutic lesioning and deep brain stimulation of the STN in patients with Parkinson's disease had rarely been complicated by hemiballismus. In addition, according to this model, lesion in GPi should result in hyperkinetic movement disorders which have not any supporting clinical or experimental evidence. On the other hand, recently, a wide community has discussed the importance of alteration in firing patterns of basal ganglia structure rather than overall firing rates as a critical mechanism for the occurrence of hemiballismus. According to this hypothesis, patients with hemiballismus have abnormal firing rates and firing patterns of the GPi. Based on the knowledge of that STN is not the only structure to alter the firing pattern of the GPi, lesions of other basal ganglia structures and motor interconnections have been hypothesized to lead to hemiballismus via disruption of the firing patterns of GPi from distinct points. Remarkably, in a recent study by Laganiere et al., a large group of patients were studied using resting-state functional connectivity MRI technique. In conclusion of their study, they found that motor pathways implicated in the hemiballismus were considerably complex and widely distributed throughout the brain. However, they also found that majority of strokes demonstrated high functional connectivity to the posterolateral putamen. I think that the presentation of this unique patient may give substantial considerations in this regard. Functional MRI study was not conducted in our patient, which unable to comment about the underlying functional networks of hemiballismus. However, repeating hemiballismus in association with distinct regions of stroke in a single patient may also support the consideration of a heterogeneous and wide range of anatomical regions functioning in this movement disorder. Furthermore, although the second stroke involved bilateral subcortical hemispheres, hemiballismus was solely left sided as in the first admission, which strictly complicates our understanding of the underlying pathophysiology.
Another interesting question may be that, although stroke constitutes a forefront etiological cause of hemiballismus, its actual incidence in poststroke patients is extremely rare, such that it was reported to occur in 0.54% cases of stroke. Therefore, it may be suggested that that there may be some structural predisposition to developing hemiballismus in this patient? Future reports of wider case series using functional neuroimaging techniques are warranted to clarify these discussions.
In conclusion, I think that the clinical course of this patient may give valuable perspectives regarding the pathophysiology of hemiballismus, supporting the theory of more complex and distributed brain regions other than the explanation in the setting of classical basal ganglia circuitry model. Future illustrations of these rare cases of strokes with movement disorders may also add crucial perspectives to our understanding of processing features of the human motor network.
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