Introduction. Panarteritis nodosa (PAN) is a systemic vasculitis affecting sma ll and medium-sized arteries. Neuro-ophthalmological complications of PAN are rare but numerous, and may affect the eye, the visual and the oculomotor pathway s. Such complications occur mainly in patients previously diagnosed with PAN. Ob servation. A 51-year-old woman presented with an isolated right trochlear (IV) palsy, in the setting of headaches and fluctuating fever of unknown etiology. E rythrocyte sedimentation rate was 13mm and full blood cell count was normal. Pre vious chest X-ray and blood studies were negative for an infection or inflammat ion. Orbital and cerebral CT scan was normal. Spontaneous recovery of diplopia e nsued over four days. Two days later, paresthesia and sensory paresis of the dor sal portion of the left foot were present. Lumbar puncture revealed 14 leucocyte s (76 percent lymphocytes) with elevated proteins, but blood studies and serolog ies were negative. A diagnosis of undetermined meningo-myelo-radiculoneuritis was made. Because of a possible tick bite six weeks previously the patient was e mpirically treated with 2g intravenous ceftriaxone for 3 weeks. Fever rapidly dr opped. Six weeks after the onset of diplopia, acute onset of blindness in her ri ght eye, diffuse arthralgias and fever motivated a new hospitalization. There wa s a central retinal artery occlusion of the right eye. Blood studies now reveale d signs of systemic inflammation (ESR 30mm, CRP 12mg/L, ANA 1/80, pANCA 1/40, le ucocytosis 12.4G/L, Hb 111g/L, Ht 33 percent). Biopsy of the left sural nerve re vealed arterial fibrinoid necrosis. A diagnosis of PAN was made. Conclusions. Tr ansient diplopia can be the heralding symptom of a systemic vasculitis such as P AN, giant cell arteritis and Wegener granulomatosis. In this patient the presenc e of accompanying systemic symptoms raised a suspicion of systemic inflammation, but the absence of serologic and imaging abnormalities precluded a specific dia gnosis initially. A few weeks later, the presence of a second ischemic event (re tinal) and positive blood studies led to a further diagnostic procedure. Oculomo tor and abducens palsies have rarely been reported in association with PAN. We r eport the first case of trochlear nerve paresis as the inaugural neurological si gn of PAN. This case highlights the importance of considering inflammatory syste mic disorders in patients with acute diplopia particularly when they are young, lack vascular risk factors or cause, and complain of associated systemic symptom s. Introduction The Panarteritis nodosa (PAN) is a systemic vasculitis affecting sma ll and medium-sized arteries. Neuro-ophthalmological complications of PAN are rare but numerous, and may affect the eye, the visual and the oculomotor pathway s. Such complications occur mainly in Patients previously diagnosed with PAN. Ob servation. A 51-year-old woman presented with an isolated right trochlear (IV) palsy, in the setting of headaches and fluctuating fever of unknown etiology. E rythrocyte sedimentation rate was 13mm and full blood cell count Previous chest X-ray and blood studies were negative for an infection or inflammat ion. Orbital and cerebral CT scan was normal. Spontaneous recovery of diplopia e nsued over four days. Two days later, paresthesia and sensory paresis of the dor sal portion of the left foot were present. Lumbar puncture revealed 14 leucocyte s (76 percent lymphocytes) with elevated proteins, but blood studies and serolog ies were negative. A diagnosis of und Because of a possible tick bite six weeks previously the patient was e mpirically treated with 2g intravenous ceftriaxone for 3 weeks. Fever rapidly dr opped. Six weeks after the onset of diplopia, acute onset of blindness in There are sa sa central retinal artery occlusion of the right eye. Blood studies now reveale d signs of systemic inflammation (ESR 30mm, CRP 12mg / L, ANA 1/80, pANCA 1/40, leuocytosis 12.4 G / L, Hb 111 g / L, Ht 33 percent). Biopsy of the left sural nerve re vealed arterial fibrinoid necrosis. A diagnosis of PAN was made. Conclusions. Tr ansient diplopia can be the heralding symptom of a systemic vasculitis such as P AN, giant cell arteritis and Wegener granulomatosis. In this patient the presenc e of systemic symptoms raised a suspicion of systemic inflammation, but the absence of serologic and imaging abnormalities precluded asA few weeks later, the presence of a second ischemic event (re tinal) and positive blood studies led to a further diagnostic procedure. Oculomo tor and abducens palsies have rarely been reported in association with PAN. We r eport the first case of trochlear nerve paresis as the inaugural neurological si gn of PAN. This case highlights the importance of considering inflammatory syste mic disorders in patients with acute diplopia particularly when they are young, lack vascular risk factors or cause, and complain of associated systemic symptom s.