High median nerve lesion secondary to severe giant cell arteritis (GCA)

ABSTRACT

Background: Giant cell arteritis (GCA) is a systemic vasculitis affecting large to medium-sized vessels. Cranial nerve lesions are frequently documented secondary to GCA, however peripheral nerves are rarely involved. Objectives: We present an unusual case of a GCA-associated isolated high median nerve palsy. Methods: Case report. Results: A 76 year old white British female presented in Spain with three weeks of frontotemporal headaches, mandibular claudication, photopsia and constitutional symptoms, followed by acute-onset right hand paresis and dysaesthesia. Acute-phase reactants were elevated. COVID-19 PCR was negative. Shortly after admission she developed acute bilateral anterior ischaemic optic neuropathy and tongue necrosis with autoamputation. Temporal artery ultrasound and biopsy confirmed GCA. PET-CT showed no evidence of a diffuse large-vessel vasculitis. She was repatriated to the UK for ongoing inpatient care. Upper limb neurophysiology two months later demonstrated an isolated right high median nerve lesion, with reduced median motor responses and absent sensory responses with denervation in extensor carpi radialis. Imaging excluded a central lesion. The timing of her symptoms suggested the lesion was secondary to GCA. Treatment was with tocilizumab, methotrexate and tapering corticosteroids, alongside PEG feeding and careful multi-disciplinary rehabilitation. Conclusion: We suggest there are two important learning points from this complex case. Firstly, peripheral nerve lesions can occur in GCA, although they are rare. A literature search identified a modest number of case reports of brachial plexus or lower cervical nerve lesions1,2. Neurologic manifestations in GCA are attributed to vasculitis of the vasa nervorum, or extension of inflammation from arteries to contiguous nerves1,2. The restriction of clinical involvement to the median nerve alone would appear to favour the former mechanism. Functional recovery of neurological deficits is typically partial at best. Secondly, this case highlights the difficulty faced by clinicians in recognising GCA and the importance of urgent treatment with glucocorticoids. The patient developed GCA during the ongoing COVID-19 pandemic when Spain was the second-worst affected European country (5% seroprevalence;95% CI 4.7-5.4)3. The partial overlap in symptoms between GCA and COVID-19 (e.g. headache, pyrexia, malaise, elevated acute-phase reactants) can cause diagnostic confusion and treatment delay4. GCA should be considered in the differential diagnosis of older patients with suspected COVID-19, or the non-specifically unwell elderly patient.