​Unilateral Pruritus Following a Cerebrovascular Accident: Understanding Post-Stroke Itch

An MRI scan showing the effects of a stroke on the brain, highlighting areas of damage caused by interrupted blood flow.

A cerebrovascular accident (CVA), commonly known as a stroke, occurs when the blood supply to a part of the brain is interrupted or reduced, depriving brain tissue of oxygen and nutrients. This can lead to various neurological deficits, depending on the area of the brain affected. While motor and speech impairments are well-recognized consequences of stroke, sensory disturbances like pruritus (itching) are less commonly discussed but can significantly impact a patient's quality of life. This article delves into the phenomenon of unilateral pruritus following a stroke, exploring its causes, manifestations, and potential treatment options.​

Understanding Post-Stroke Pruritus

Pruritus, or itching, is a common symptom associated with various dermatological conditions. However, when itching arises due to central nervous system (CNS) lesions, it is termed central or neuropathic pruritus. Post-stroke pruritus is a rare manifestation resulting from lesions within the brain that affect neural pathways responsible for the sensation and modulation of itch. The exact pathophysiology remains unclear, but studies suggest that damage to specific brain regions can disrupt normal sensory processing, leading to pruritus.​

Case Studies Highlighting Unilateral Pruritus Post-Stroke

Several case studies have documented instances of unilateral pruritus following a stroke

• Case 1: A 52-year-old male experienced severe, continuous itching on the left side of his body ten days after suffering a stroke that resulted in left-sided hemiparesis. Physical examination revealed numerous excoriations on the left arm, trunk, and thigh, with the right side remaining unaffected. Imaging studies showed multiple infarcts involving the left cerebellar hemisphere and acute infarcts in various areas of the brain, primarily in the distribution of the right anterior and middle cerebral arteries. Lacunar infarcts were also noted in the right internal capsule and parts of the right thalamus. The patient was treated with amitriptyline 25 mg daily, resulting in marked improvement of pruritus after 15 days. 

• Case 2: A 77-year-old woman developed severe itch associated with thick nodules on the right side of her head, trunk, and upper limb two years after experiencing an ischemic stroke in the left lateral medulla. Despite various treatments, including corticosteroids and antihistamines, her condition persisted. A biopsy confirmed prurigo nodularis (PN), and treatment with dupilumab, an anti-interleukin-4/13 drug, led to a significant reduction in itch intensity and lesion size after 16 weeks.

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Mechanisms Behind Post-Stroke Pruritus

The sensation of itch is complex and involves multiple brain regions, including the anterior cingulate cortex, premotor area, primary somatosensory cortex, insular cortex, supplementary motor area, cerebellum, and thalamus. Damage to these areas can disrupt normal sensory processing, leading to pruritus. Notably, both itch and pain sensations are mediated by anatomically identical but functionally distinct C-fibers. Brain areas activated during itch and pain also have some degree of overlap, and pruritus can remit with painful stimuli. ​

Diagnosis and Clinical Presentation

Patients with post-stroke pruritus typically present with itching localized to one side of the body, corresponding to the contralateral side of the brain lesion. The onset of pruritus can be delayed, occurring weeks to months after the initial stroke event. A detailed patient history, thorough clinical examination, and relevant imaging studies are essential to establish the diagnosis and rule out other potential causes

Treatment Approaches

Managing post-stroke pruritus can be challenging due to its central origin. 

• Medications: Amitriptyline, a tricyclic antidepressant, has been used with success in some cases. Other treatments, such as gabapentinoids and anti-seizure medications, may also be considered. ​ijdvl.com

• Biologic Therapies: In cases of prurigo nodularis associated with post-stroke pruritus, biologic therapies targeting specific inflammatory pathways, such as dupilumab, have shown promise. ​

  
  

Conclusion

Unilateral pruritus following a cerebrovascular accident is a rare but impactful condition that can significantly affect a patient's quality of life. Recognizing this condition is crucial for timely and effective management. Further research is needed to fully understand the mechanisms underlying post-stroke pruritus and to develop targeted therapies to alleviate this distressing symptom.