From the Guidelines
A right internal capsule infarct typically presents with contralateral hemiparesis, sensory deficits, and occasionally neglect, with management including acute stroke protocols, antiplatelet therapy, and rehabilitation. The clinical presentation of a right internal capsule infarct follows a pure motor or sensorimotor stroke syndrome pattern due to damage to the corticospinal and thalamocortical pathways that run through the internal capsule 1. On imaging, a right internal capsule infarct appears as a small, focal area of restricted diffusion on MRI diffusion-weighted imaging or as a hypodense lesion on CT in the region of the right internal capsule.
Key Findings
- Contralateral hemiparesis (weakness) that is more pronounced in the face and upper extremity than the lower extremity
- Contralateral sensory deficits
- Dysarthria (slurred speech)
- Occasionally contralateral neglect
- Small, focal area of restricted diffusion on MRI diffusion-weighted imaging
- Hypodense lesion on CT in the region of the right internal capsule
Management
- Acute stroke protocols if identified early
- Antiplatelet therapy (such as aspirin 81-325 mg daily or clopidogrel 75 mg daily)
- Statin therapy
- Blood pressure control
- Rehabilitation The internal capsule receives blood supply primarily from the lenticulostriate branches of the middle cerebral artery, making small vessel disease a common cause of these infarcts, as seen in a study published in Stroke 1. Prognosis is variable but many patients show good functional recovery with appropriate rehabilitation due to the small size of these lesions, though some residual weakness may persist.
From the Research
Right Internal Capsule Infarct Findings
- A right internal capsule infarct can cause left motor neglect, as seen in a case report where a 69-year-old man had left motor neglect following an infarct of the anterior limb of the right internal capsule 2.
- The infarct can also lead to left auditory extinction on verbal dichotic listening and slight constructional apraxia, as observed in the same case report 2.
- Regional cerebral blood flow (CBF) measurements have shown a decrease in CBF in a diffuse fashion, and motor activation of the right hand resulted in an increase of CBF in the contralateral superior rolandic area, whereas no such increase was found during motor activation of the left hand 2.
- A study on posterior internal capsule infarction associated with neglect found that a small infarction of the posterior limb of the right internal capsule can cause persistent hemispatial neglect, restricted to tasks requiring spontaneous motor performance on the contralateral hemispace 3.
- Another study reported a case of strategic-infarct mild cognitive impairment, where a lacunar infarction in the genu of the right internal capsule extended to the anterior thalamus led to amnestic symptoms, possibly due to thalamocortical disconnection 4.
Mechanisms and Treatment
- The mechanisms underlying ischemic stroke and neuronal injuries are complex, and the infarct size and neurological severity after ischemic stroke episodes depend on various factors, including the time period since occurrence, the severity of ischemia, and the location of infarcts 5.
- Treatment for ischemic stroke and cerebral infarcts is ongoing, with various clinical trials and up-to-date treatments being applied, including antiplatelet therapy, such as aspirin, which has been proven to prevent ischemic stroke in various settings 6.