Figure 4: (A) The subthalamic nucleus (excitatory) is directly activated by cortical inputs, enhancing the inhibitory activity of the globus pallidus internus. This leads to increased inhibition of the thalamus and decreased motor output. (B) When the cortex is impaired, the inhibition of the thalamus decreases, and motor output increases.

Multiple isolated cases of hemichorea secondary to cortical ischemic lesions have been reported in the literature, involving various cortical regions, including frontal, parietal, insular, and supplementary motor areas [3,5,8,9]. A summary of previously reported cases is presented in Table 2. An alternative mechanism that should be considered is regional hypoperfusion related to large- or medium-vessel disease. The small size of cortical infarcts observed in our patients suggests that abnormal movements may not be solely explained by structural lesions, but rather by dysfunction of distributed motor networks [10,11]. This mechanism may overlap with limb-shaking TIAs, further complicating the diagnostic approach.

This hypothesis is supported by previous reports describing hyperkinetic movement disorders in the setting of hemodynamic impairment, particularly in patients with carotid artery stenosis or occlusion [2,5]. In such cases, abnormal movements, including limb-shaking transient ischemic attacks, have been attributed to transient cerebral hypoperfusion and may improve following revascularization procedures [5].

Similarly, cortical hypoperfusion may disrupt cortico–basal ganglia circuits without direct structural damage to deep nuclei, leading to abnormal motor output [1,2]. These findings support the concept that both structural lesions and functional hemodynamic disturbances contribute to the pathophysiology of hemichorea in cortical stroke.

Although perfusion imaging was not systematically available in our series, the vascular findings and the small lesion size strongly suggest a potential hemodynamic contribution.

Low-dose haloperidol (2–3 mg/day) was effective and well tolerated in four of our patients, producing complete or near-complete resolution within days. One patient responded to levetiracetam, consistent with the overlap between cortical hyperexcitability and hyperkinetic phenomena. When haloperidol is undesirable because of extrapyramidal or cardiac risk in elderly stroke patients, tetrabenazine, atypical neuroleptics (olanzapine, risperidone) or valproic acid may be considered. However, in most post-stroke hemichoreas the movements are self-limited over days to weeks, and aggressive long-term symptomatic therapy is rarely required.

Another important consideration relates to the clinical recognition of hemichorea as a potential manifestation of acute ischemic stroke. In some cases, involuntary movements may represent the predominant or sole neurological sign, which may lead to diagnostic uncertainty and delay in appropriate neuroimaging. Awareness of this atypical presentation is therefore crucial, particularly in patients with vascular risk factors [3,5].

An additional clinical implication concerns the possibility that hemichorea may reveal an acute ischemic stroke occurring within the therapeutic window for reperfusion therapy. In such circumstances, the neurological deficit may appear minor according to conventional stroke severity scales such as the NIH Stroke Scale, which primarily evaluates motor weakness, language impairment, and level of consciousness but does not adequately capture hyperkinetic movement disorders [10, 12]. Consequently, patients presenting with isolated hemichorea may have a very low NIHSS score despite the presence of an acute cortical infarction.

This situation may create a therapeutic dilemma regarding eligibility for acute reperfusion strategies such as intravenous thrombolysis or mechanical thrombectomy. Current international guidelines indicate that reperfusion therapy may be considered in patients presenting with minor but potentially disabling symptoms [12]. Although hemichorea is rarely discussed in this context, severe involuntary movements may significantly interfere with voluntary motor control, gait, and daily activities, thereby representing a potentially disabling neurological deficit despite a low NIHSS score [2, 3]. Failure to recognize hemichorea as a manifestation of acute ischemic stroke may therefore lead to missed opportunities for timely reperfusion therapy, even though functional recovery is often favorable, as reported in previous cases in the literature (Table 2) and similarly observed in our series.

Our findings underscore the importance of considering vascular etiologies in patients presenting with sudden onset hemichorea. Early brain imaging, particularly diffusion-weighted MRI, remains essential to establish the diagnosis and guide management. Greater awareness of this atypical clinical presentation may improve early stroke recognition and facilitate appropriate therapeutic interventions.

Finally, several limitations should be acknowledged. The relatively small number of patients reflects the rarity of this clinical presentation. In addition, the retrospective design may introduce potential biases in case identification and clinical characterization. Perfusion imaging and intra-arterial vascular imaging were not systematically performed, precluding definitive correlation between hemodynamic status and clinical expression. Video documentation was not available for all patients. Nevertheless, our series contributes to the growing body of literature suggesting that cortical infarctions may represent an underrecognized cause of hemichorea and highlights the need for further studies to better understand the mechanisms and therapeutic implications of this phenomenon.

Key Clinical Messages

• Acute hemichorea may be the sole presenting manifestation of cortical ischemic stroke.
• Stroke severity may be underestimated using the NIH Stroke Scale in such cases.
• Brain MRI should be systematically performed in patients with acute-onset movement disorders of unclear origin.
• Hemichorea may represent a potentially disabling symptom despite low NIHSS scores and should not preclude consideration of reperfusion therapy.
• Differential diagnosis includes limb-shaking transient ischemic attacks and focal motor seizures.
• Vascular and hemodynamic mechanisms should be considered, particularly in patients with large-vessel disease.
• Small cortical infarcts sparing M1 and the corticospinal tract may produce disinhibition of the cortico-subthalamic hyperdirect pathway, explaining hyperkinetic movements without weakness.