Peripheral polyneuropathy and Churg–Strauss syndrome

Dear Editor:

Churg–Strauss syndrome (CSS) is a systemic disease characterised by asthma, pulmonary infiltrates, hypereosinophilia, and systemic vasculitis. Eosinophilic vasculitis can involve many organs, including the lungs, heart, skin, gastrointestinal tract, and nervous system, principally the peripheral nervous system (PNS).¹ We present 3 cases in which CSS was diagnosed due to PNS involvement, thus highlighting the severity of this disease and the need for early diagnosis and treatment.

Patient 1 was a 72-year-old man with personal history of nasal polyps. He had symptoms of motor and sensory peripheral polyneuropathy, a 5-month history of toxic syndrome, and ataxic gait for which he needed bilateral support. CSS was diagnosed based on findings of eosinophilia, p-ANCA positivity, diffuse pulmonary infiltrates, and EMG showing mixed axonal polyneuropathy in a moderate to severe stage. Infectious and/or neoplastic processes had previously been ruled out. He was started on remission induction treatment with prednisone dosed at 1 mg/kg/day and intravenous bolus cyclophosphamide as well as symptomatic treatment. After a few days, eosinophilia disappeared and respiratory symptoms improved progressively. Neurological symptoms only showed discrete improvement.

Patient 2 was a 45-year-old man with personal history of arterial hypertension and asthma. He showed symptoms of axonal sensorimotor polyneuropathy which had been developing over 3 months, eosinophilia, pansinusitis, pulmonary infiltrates, p-ANCA positive test results, and skin lesions. Sural nerve biopsy showed signs compatible with vasculitis. After being diagnosed with CSS, he started treatment with prednisone; when neurological involvement progressed, intravenous bolus of cyclophosphamide was added. Once respiratory symptoms had resolved and neurological symptoms had also resolved partially, the patient started maintenance treatment with azathioprine. During treatment, he suffered 2 vertebral fractures due to secondary osteoporosis and showed reactivation of hepatitis B and iatrogenic Cushing syndrome. He is currently treated with azathioprine; dysaesthesia and ataxic gait persist.

Patient 3 was a 22-year-old man with personal history of asthma and rhinitis. He showed symptoms of mixed axonal polyneuropathy over a 2-month period with eosinophilia, positive ANCA test, and interstitial pneumonitis. The patient started induction treatment with decreasing doses of corticosteroids and 5 doses of cyclophosphamide. Clinical response was excellent. After that, he was treated with azathioprine as maintenance treatment. He is currently asymptomatic.

The incidence of CSS is 2.4 cases/million person-years in the general population; among asthma patients, the rate is 12.5 to 20 times higher, reaching up to 64 cases/million person-year. The syndrome is more frequent in men. It can appear in patients with a history of allergy and atopy, and it may develop over 30 years before any systemic manifestations are observed. It manifests in 3 stages and asthma seems to present years before the other symptoms do.

At the systemic level, it mainly affects the lungs, followed by the skin and the PNS (80%).^2,3 When the PNS is affected, patients experience paraesthesia and dysaesthesia predominantly on the soles of the feet, hiccups, loss of strength, or patellar tendon and Achilles tendon areflexia. Involvement mainly manifests as mononeuritis multiplex or distal symmetric sensorimotor axonal polyneuropathy.^4,5

Treatment must be aggressive and immediate, using high-dose corticosteroids and/or cytostatic drugs.^6,7 Initial treatment uses oral corticosteroids (1 mg/kg/day) to induce remission as soon as possible. The dose is then progressively decreased to continue with maintenance treatment. In cases of complications or poor response to these drugs, intravenous cyclophosphamide pulses, followed by azathioprine, are to be used. Cyclophosphamide would only be indicated as a first-line treatment if factors are present that indicate poor prognosis (proteinuria >1 g/day, creatinine >1.58 mg/dL, PNS involvement). Response to treatment with intravenous immunoglobulins^5,8 or rituximab⁹ has been described in some cases.

By presenting these cases, we aim to highlight the need for early diagnosis and intensive treatment, considering the high degree of impairment caused when CSS is accompanied by PNS involvement.