From the Guidelines
The patient with a reported right internal capsule infarct but presenting with right hemiparesis should undergo urgent neurological reevaluation with repeat imaging to correctly identify the pathology, as this presentation suggests a possible misdiagnosis or rare anatomical variant. This situation is unusual because typically, lesions in the internal capsule cause contralateral symptoms due to the crossing of descending motor pathways at the level of the medulla 1. The most likely explanation is that the infarct is actually in the left internal capsule, which would normally cause right-sided weakness. Alternatively, there could be an undetected lesion in the left hemisphere or brainstem causing the right hemiparesis.
Key considerations in managing this patient include:
- Urgent repeat imaging to confirm the location and extent of the infarct
- Comprehensive neurological examination to assess for any other deficits
- Review of initial imaging studies to rule out any errors in interpretation
- Initiation of standard stroke protocols, including appropriate antithrombotics and blood pressure management, without delay
- Early rehabilitation to optimize outcomes
The importance of accurate diagnosis cannot be overstated, as it guides not only the immediate management but also the secondary prevention strategies. The patient should be monitored closely for progression of symptoms, and a thorough workup for stroke etiology should be completed to inform decisions on long-term management and prevention of future events, as outlined in guidelines for the management of cerebral infarction 1.
From the Research
Right Internal Capsule Infarct and Right Hemiparesis
- The presence of a right internal capsule infarct typically results in left hemiparesis, not right hemiparesis, due to the contralateral control of the brain's motor systems 2.
- However, there are cases where the expected pattern of hemiparesis does not occur, and the underlying mechanisms for such exceptions are not fully understood.
- A study on ataxic hemiparesis, another lacunar syndrome, found that ipsilateral ataxia in patients with capsular infarct may be caused by ipsilateral red nucleus dysfunction secondary to cortico-rubral pathway disruption at the internal capsule 3.
Potential Explanations
- One possible explanation for the occurrence of right hemiparesis with a right internal capsule infarct could be the simultaneous development of dual strokes, as seen in a case report where a patient presented with both an internal capsule infarct and a cerebellar hemorrhage 2.
- Another possibility is that the infarct affects specific pathways or brain regions that result in unusual patterns of motor deficits.
- The use of anticoagulation therapy in patients with acute ischemic stroke, including those with internal capsule infarcts, may also play a role in the development of hemiparesis, although the current consensus is that anticoagulation has no role acutely in the management of ischemic stroke 4, 5.
Treatment and Management
- The management of patients with internal capsule infarcts and hemiparesis typically involves rehabilitation and supportive care to address the resulting motor deficits.
- Anticoagulation therapy may be considered in certain cases, such as in patients with cerebral venous and sinus thrombosis, but its use in acute ischemic stroke is still debated 4, 5.
- Low-dose anticoagulation may be used to prevent venous thromboembolic events, but its effectiveness in reducing hemorrhagic transformation in acute ischemic stroke is still being studied 6, 5.