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Takayasu’s arteritis or aortoarteritis affects the aorta and its proximal branches.1 Cranial nerve involvement in the form of ischaemic optic neuropathy secondary to proximal carotid involvement is common.2 Involvement of other cranial nerves has been reported only once before.3 We report two patients with aortoarteritis who developed isolated cranial nerve palsies. Notably, in both cases it occurred without proximal carotid involvement.
Patient 1, a 30 year old businessman, presented with malignant hypertension because of right renal artery stenosis due to aortoarteritis affecting the abdominal aorta. After successful balloon angioplasty, blood pressure was well controlled with antihypertensive drugs. Two years later he developed sudden headache and diplopia on looking towards the left. Examination showed a convergent squint in the left eye due to abducens nerve palsy. Contrast enhanced brain computed tomography (CT) scan and cerebrospinal fluid (CSF) analysis were normal. Angiography showed that the aortic arch and its branches were normal; the suprarenal abdominal aorta showed irregular narrowing with stenosis of the left renal artery and the previously balloon-dilated right renal artery. On treatment with 1 mg/kg/day of prednisolone he recovered completely in 10 days.
One year later he developed diplopia again. This time he was found to have right abducens nerve palsy. Angiography showed normal carotid vessels but complete occlusion of the left subclavian artery 1 cm distal to its origin. Again, he made a complete recovery with 1 mg/kg of prednisolone over 20 days.
Patient 2, an 18 year old female student, was admitted for accelerated hypertension. A renal Doppler examination showed left renal artery stenosis. On aortography she had an irregular contour with narrowing of the abdominal aorta and occlusion from the origin of the left renal artery, suggestive of aortoarteritis. She refused renal angioplasty and was treated with antihypertensive drugs. Four years later she developed sudden diplopia and right eyelid ptosis. Examination showed complete ptosis on the right, divergent squint, and ophthalmoplegia, suggestive of isolated right oculomotor palsy. The pupil, however, was normal in size and constricted briskly in light. Contrast enhanced brain CT scan, CSF analysis, and four-vessel angiogram were normal. She received 1 mg/kg of prednisolone for 30 days with complete recovery.
Both patients satisfied Ishikawa’s diagnostic criteria for aortoarteritis,4 and presented with sudden onset of isolated cranial nerve palsies. The normal CT scans and CSF examination excluded structural and infective aetiologies of cranial nerve palsies. The sudden onset of deficits in both patients suggested a vascular cause. Moreover, recurrence of the cranial nerve deficit on the contralateral side in patient 1 and the presence of pupillary sparing in patient 2 further supported a vascular aetiology. The pupil is characteristically unaffected in ischaemic oculomotor nerve palsy because the pupillary fibres, which are outermost, receive additional blood supply from the pial (meningeal) vessels and are therefore spared in oculomotor nerve infarction.5
The oculomotor and abducens nerves derive their arterial supply from the inferolateral trunk, which originates from the intracavernous siphon of the internal carotid artery.6 In our patients the extracranial carotid circulation and the siphon of the internal carotid artery were angiographically normal, suggesting involvement of small sized vessels supplying the cranial nerves. Nuclear brainstem infarcts could also cause cranial nerve deficits7 and a magnetic resonance imaging study (not done in our patients) would be most sensitive to diagnose them. However, this is very unlikely owing to the absence of signs of involvement of the brainstem ascending or descending tracts and rapid complete recovery of deficits with corticosteroids.
Small vessel involvement has been described in some patients with aortoarteritis. Manifestations of these include glomerulonephritis,10 interstitial lung disease,11 and necrotising vasculitic lesions of the skin.12 It is likely that cranial nerve palsies in our patients too might be due to similar small vessel involvement in the central nervous system.