Introduction. La panartérite noueuse (PAN) est une vasculite systémique touchant les artères de petit et moyen calibre. Les atteintes neuro-ophtalmologiques sont nombreuses mais rares et s’inscrivent habituellement dans le cadre d’une PAN connue. Observation. Une femme de 51 ans présenta une parésie trochléaire (IV) droite dans le cadre de céphalées et d’un état fébrile fluctuant. Le scanner X cérébral et orbitaire était normal. La diplopie régressa spontanément en quatre jours. Deux jours plus tard, elle présenta une parésie sensitive du pied gauche. En l’absence de signes sérologiques inflammatoires ou infectieux, mais en présence d’une pléocytose lymphocytaire et d’une hyperprotéinorachie à l’examen du liquide céphalo-rachidien, un diagnostic de méningo-myélo-radiculonévrite d’étiologie indéterminée fut posé. Cinq semaines plus tard, la patiente présenta soudainement une occlusion de l’artère centrale de la rétine droite. Une biopsie du nerf péronier court et du muscle péronier latéral amena au diagnostic de PAN. Conclusions. Une diplopie n’est que rarement présente dans une PAN, à plus forte raison comme symptôme neurologique inaugural. De rares cas de parésies des nerfs III et VI ont été rapportés dans le cadre d’une PAN. À notre connaissance, cette patiente représente le premier cas de parésie isolée du IV comme signe neurologique inaugural d’une PAN.

Introduction. Panarteritis nodosa (PAN) is a systemic vasculitis affecting small and medium-sized arteries. Neuro-ophthalmological complications of PAN are rare but numerous, and may affect the eye, the visual and the oculomotor pathways. Such complications occur mainly in patients previously diagnosed with PAN. Observation. A 51-year-old woman presented with an isolated right trochlear (IV) palsy, in the setting of headaches and fluctuating fever of unknown etiology. Erythrocyte sedimentation rate was 13mm and full blood cell count was normal. Previous chest X-ray and blood studies were negative for an infection or inflammation. Orbital and cerebral CT scan was normal. Spontaneous recovery of diplopia ensued over four days. Two days later, paresthesia and sensory paresis of the dorsal portion of the left foot were present. Lumbar puncture revealed 14 leucocytes (76 percent lymphocytes) with elevated proteins, but blood studies and serologies were negative. A diagnosis of undetermined meningo-myelo-radiculoneuritis was made. Because of a possible tick bite six weeks previously the patient was empirically treated with 2g intravenous ceftriaxone for 3 weeks. Fever rapidly dropped. Six weeks after the onset of diplopia, acute onset of blindness in her right eye, diffuse arthralgias and fever motivated a new hospitalization. There was a central retinal artery occlusion of the right eye. Blood studies now revealed signs of systemic inflammation (ESR 30mm, CRP 12mg/L, ANA 1/80, pANCA 1/40, leucocytosis 12.4G/L, Hb 111g/L, Ht 33 percent). Biopsy of the left sural nerve revealed arterial fibrinoid necrosis. A diagnosis of PAN was made. Conclusions. Transient diplopia can be the heralding symptom of a systemic vasculitis such as PAN, giant cell arteritis and Wegener granulomatosis. In this patient the presence of accompanying systemic symptoms raised a suspicion of systemic inflammation, but the absence of serologic and imaging abnormalities precluded a specific diagnosis initially. A few weeks later, the presence of a second ischemic event (retinal) and positive blood studies led to a further diagnostic procedure. Oculomotor and abducens palsies have rarely been reported in association with PAN. We report the first case of trochlear nerve paresis as the inaugural neurological sign of PAN. This case highlights the importance of considering inflammatory systemic disorders in patients with acute diplopia particularly when they are young, lack vascular risk factors or cause, and complain of associated systemic symptoms.