Case Presentation: A 53 year-old woman presented with bilateral foot drop. She reported one-month history of progressive clumsiness and a weak hand grip. These symptoms began with an initially painful rash on her feet. She denied fatigue, myalgia, arthralgia, confusion, dizziness, or loss of bowel or bladder function. She denied recent illness or travel. Past medical history was notable for adult-onset allergic sinusitis and asthma refractory to conventional management. Previous lung imaging revealed patchy opacities. Multiple sinus surgeries with tissue biopsies noted eosinophilic infiltration. Screening for ANCA twelve years prior was negative. She had no personal or family history of Diabetes Mellitus or neuromuscular diseases. She had never smoked tobacco and drank alcohol occasionally.
She had weak flexion and extension in her feet and flexion in her wrists. Ankle reflexes were diminished. Small non-tender nodules were noted on plantar surfaces. Sensation to light touch, pinprick, and vibration were diminished in lower extremities. Proprioception was diminished in her great toes. Temperature sense remained intact. She exhibited a wide-based ataxic gait and was unable to walk on tip-toes or heels. Foot drop was present bilaterally.
She had eosinophilia with an absolute count of 14,600/mL and 65 percent predominance, along with elevated CRP and ESR, trace hematuria, and a positive ANA and p-ANCA. EMG revealed axonal asymmetric sensorimotor neuropathy. Hemoglobin A1c and TSH were unremarkable. Extensive infectious work-up was negative, as were vitamin levels, brain and cervical spine MRI, electrocardiogram, and echocardiogram.
She actually met diagnostic criteria for EGPA years prior to the development of vasculitic neuropathy and bilateral foot drop.
Discussion: EGPA (formerly Churg-Strauss or allergic granulomatosis and angiitis) is a vasculitis of small and medium sized vessels characterized by allergic rhinitis, asthma, and peripheral eosinophilia. It occurs in 18 out of every 1,000,000 people and accounts for 10 percent of vasculitis cases. It is associated with p-ANCA in approximately 50 percent of cases but it is not part of the diagnostic criteria. The diagnostic criteria for EGPA require four of the following to be present: paranasal sinus abnormalities, asthma, non-fixed pulmonary opacities on radiography, greater than 10 percent eosinophils, biopsy revealing extravascular eosinophils, and mononeuropathy or polyneuropathy.
EGPA classically presents in three sequential phases. Atopy is representative of the prodromal phase. Peripheral eosinophilia and eosinophilic infiltration of organs, most notably the lungs, is characteristic of the eosinophilic phase. The vasculitic phase commonly manifests as neuropathy, most specifically mononeuritis multiplex, but it may give rise to serious extra-pulmonary complications that account for the majority of mortality in EGPA.
Conclusions: It is essential that internists are able to recognize EGPA as early as possible in the disease course. Early diagnosis and treatment can prevent the development of the irreversible vasculitic stage and the associated extra-pulmonary complications.