A Woman With A Persistent Pruritic Arm

A 65-year-old woman with history of well-controlled type II diabetes, hypertension, hyperlipidemia, and hypothyroidism presented to her primary care physician with persistent left arm pruritus for 4 months.

Pruritus is a common patient concern with a broad differential that is frequently encountered by clinicians. Brachioradial pruritus is an uncommon neuropathic pruritus that negatively impacts quality of life. Due to its unknown prevalence, many physicians may be unfamiliar with this condition, leading to a difficult and delayed diagnosis. This case illustrates that clinicians should maintain a high level of suspicion when a patient presents with persistent arm pruritus.

Case description. The patient initially noticed intermittent pruritus on her left hand. The symptom gradually extended up to the left wrist, forearm, arm, and posterior shoulder. She denied numbness, pain, or muscle weakness. There was no change in medications, food, soap, lotion, or clothing. Her medications included metformin, losartan, hydrochlorothiazide, rosuvastatin, and levothyroxine.

Her physical examination was unremarkable except for scattered excoriations on the left dorsolateral arm and posterior shoulder along the C5 and C6 dermatomes. Her most recent HbA1C prior to this visit was 6.4%. Other laboratory values including complete blood count, electrolytes, thyroid, liver and renal functions were all within normal limits. A course of topical 0.1% triamcinolone cream used twice daily for 4 weeks prescribed by the primary care physician failed to alleviate her pruritus.

She was referred to a dermatologist who considered brachioradial pruritus (BRP), neurodermatitis, and dermatitis artefacta. A skin biopsy showed ulcerated epidermis with overlying hemorrhagic scale crust and a few telangiectatic blood vessels and slight solar elastosis within the dermis, which was consistent with BRP and ruled out the other differential diagnoses.

Cervical spine magnetic resonance imaging (MRI) showed mild spinal stenosis at C4-5 and C5-6 levels, with the left side greater than the right side, and multilevel foraminal narrowing. She was treated with topical 0.1% capsaicin cream 3 times daily for 4 weeks, physical therapy, and chiropractic manipulation without improvement of her symptom. The use of topical pramoxine hydrochloride and an ice pack provided some temporary relief of the pruritus. The patient declined oral medications or invasive procedures due to potential adverse effects such as fatigue and dizziness for oral medications and bleeding and infection for invasive procedures. The patient continues to experience mild symptoms during follow-up appointments.

Discussion. BRP is an uncommon neuropathic pruritus with a poorly understood etiology that often negatively affects a person’s sleep and quality of life. It is thought to be secondary to cervical spine pathology (such as degenerative disc disease and neural foraminal stenosis) and excessive exposure to ultraviolet radiation (UVR).^1-4 Prior studies have speculated that BRP may occur due to UV damage to nerve endings in an at-risk population with cervical spine pathology.^1-3 Adult females (3:1 ratio) with lighter skin are predominately affected. While there is a mean age of 59 years, cases have been reported in patients aged 12 to 84 years.¹

The condition is characterized by relentless pruritus, burning, tingling, or stinging in the dorsolateral arms along the C5 and C6 dermatomes.¹ The symptom may be unilateral or bilateral, though the latter is more common.⁴ Physical findings include excoriations, prurigo nodules, and lichenification secondary to scratching of irritated skin. An ice pack applied to affected area which immediately relieves the symptom is pathognomonic of BRP and can aid diagnosis when clinically suspected. However, most clinicians are unfamiliar with this condition and the diagnosis is often delayed. Patients are typically evaluated by multiple specialists including dermatologists, neurologists, or pain management specialists, and undergo unnecessary procedures such as invasive skin biopsies, MRIs, or electrodiagnostic studies.

The management of BRP can also be challenging due to a lack of consensus on optimal treatment strategies. Various therapeutic options, including topical and oral medication therapy, physical therapy, chiropractic manipulation, acupuncture, corticosteroid injections, and surgical interventions, have been described in the literature with mixed results.^1,5-9 UV exposure avoidance may be recommended due to its potential benefit and lack of adverse effects. A recent systematic review¹⁰ suggests that gabapentin 700 to 1800 mg/day and pregabalin 100 to 225 mg/day relieve BPR symptoms and may be considered as the first-line treatment given their known safety profile. A capsaicin 8% patch appears to be cost-effective and may be considered as the second-line option. Tricyclic antidepressants, particularly amitriptyline 700 to 1800 mg/day, appear to be effective but may be limited by their adverse effects such as dizziness, fatigue, and constipation. Antihistamines and topical corticosteroids are of no benefit. Patients with confirmed cervical spine disease may benefit from spine-directed therapies, including physical therapy, chiropractic manipulation, and acupuncture. Patients who have failed conservation treatment may consider corticosteroid injection and cervical discectomy or fusion. The quality of the data, however, is poor as this review is mostly based on limited case reports and case studies.¹⁰ Future randomized controlled trials are needed to investigate the optimal therapeutic intervention.

Conclusion. Brachioradial pruritus is an uncommon chronic condition that can significantly affect a patient’s quality of life with its attack-like pruritis, burning, stinging, and tingling. This case report highlights the need for a high index of suspicion when a clinician encounters a patient with persistent arm pruritus in the C5-C6 dermatomes. An ice pack should be applied to affected areas when suspected to aid diagnosis. The patient may be treated with gabapentin, pregabalin, capsaicin 8% patch, or tricyclic antidepressants before pursuing more invasive procedures.