Foot-drop: an unusual complaint in Henoch–Schönlein purpura

Abstract

Sirs, Involvement of the peripheral nervous system in Henoch– Schonlein purpura (HSP) is rare [1]. Here, we introduce the reader to an uncommon neural manifestation of HSP in the lower limb. A 15-year-old boy presented at the emergency room of a hospital in Divan dare, a small city in the west of Iran, with abdominal pain, fever, bloody diarrhea and melena, arthralgia (both knees and elbows), gross hematuria, and palpable purpura on the buttock and behind the thigh. He was diagnosed with HSP and was treated with prednisolone 30 mg/day, which was reduced to 10 mg/day upon his discharge. He was admitted for 6 days, and, when he was discharged, the skin lesions had improved. Two weeks later, the patient developed a right-side incomplete foot-drop, which brought him to our center, Shariati Hospital. On his admission, hematuria and facial edema were observed. Physical examinations were not revealing, except for impaired dorsal flexion of the right ankle. Para-clinical findings were consistent with HSP: proteinuria (3,900 mg/24 h), and normal levels of C3, C4, and CH50. Results of tests for viral markers [hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV)], antinuclear antibodies (ANAs), cytoplasmic anti-neutrophilic cytoplasmic antibodies (C-ANCAs,) perinuclear anti-neutrophilic cytoplasmic antibodies (P-ANCAs) and cryoglobulin were negative. Serum level of immunoglobulin A (IgA) was 218 mg/dl (normal range 70–400 mg/dl). Ultrasonic evaluations of the urinary tract showed normal findings, except for increased cortical echogenicity of both kidneys. Histopathologic assessment of the renal biopsy showed diffuse mesangio-proliferative lesion with focal endocapillary proliferation and cellular crescents in 15% of the glomeruli. Immuno-fluorescence studies demonstrated IgA (2+) and C3 (1+) depositions in the mesangium. Electromyography and nerve conduction velocity (EMG/NCV) suggested mononeuropathy of the right deep proneal nerve, but, because the patient was unwilling, neural biopsy was avoided. Though not proven pathologically, the cause of the dropped foot was assigned to the underlying HSP, and an aggressive therapeutic strategy was adopted: intravenous administration of methylprednisolone (500 mg; three doses) and cyclophosphamide (750 mg), followed by oral treatment with prednisolone 15mg/day, which was increased to 40 mg/day (1 mg/kg) upon his discharge. Impaired dorsiflexion started to improve after 1 week from the beginning of the treatment. Although the patient received cyclophosphamide pulses monthly for three times, the hematuria relapsed when it was discontinued. With prescription of azathiopurine (100 mg/day) as an alternative, renal activity of HSP subsided again. Now, the patient has trace hematuria without proteinuria, and the foot drop has improved completely. The clinical feature of our patient was completely compatible with HSP. Although other vasculitis, especially microscopic polyarteritis nodosa (PAN), was demonstrated as differential diagnosis, the result of the renal biopsy, which showed mesangial deposition of IgA, confirmed the diagnosis [1]. Headaches and changes in mental status are the most frequent neurologic complications of HSP, followed by seizures, focal neurologic deficits, mononeuropathies, and polyradiculoneuropathies [2]. By reviewing the literature we found three reports of an association of HSP with manifestations of the peripheral nervous system (PNS), including involvement of the posterior tibial nerve Pediatr Nephrol DOI 10.1007/s00467-008-0952-5