Neurology India, Vol. 58, No. 3, May-June, 2010, pp. 457-459
Cerebral miliary micro aneurysms in polyarteritis nodosa : Report of two cases
Sandeep Sharma, Subhash Kumar, NK Mishra, SB Gaikwad
Department of Neuroradiology, AIIMS, New Delhi, India
Date of Acceptance: 01-Feb-2010
Code Number: ni10116
Cerebral involvement is rare in polyarteritis nodosa (PAN) and is mostly characterized by ischemic events and intracranial hemorrhages secondary to cerebral aneurysms is extremely rare. We report two patients of PAN with multiple intracranial aneurysms. One patient presented with intracerebral hemorrhage and in the other patient multiple intracranial aneurysms were incidental findings and were asymptomatic. Both our cases suggest that multiple intracranial aneurysms are not very uncommon in PAN and cerebral angiography should be considered while doing abdominal angiogram in these patients.
Keywords: Cerebral micro aneurysms, poly arteritis nodosa, SAH
Polyarteritis nodosa (PAN) is a rare systemic necrotizing vasculitis of small and medium sized arteries with predilection for certain organ systems. The reported prevalence is less than 31 per million population. More often occurs in males and in the age group of 40 to 60 years. , Involvement of cerebral vascular system in PAN is very uncommon.  We report two patients with multiple tiny aneurysms scattered throughout the cerebral vasculature.
A 13-years boy presented to the emergency with one episode of seizure followed by unconsciousness. Computed tomography (CT) brain [Figure - 1] revealed a large left frontal hematoma. Past history was significant: he used to have on and off fever and had weight loss since five months. He had undergone appendicectomy two months before this admission for recurrent abdominal pain. He also had transient right facial weakness for two days one month before. Angiography revealed multiple tiny aneurysms involving the visceral, muscular [Figure - 2] and cerebral [Figure - 3] arteries, highly suggestive of PAN. Clinically he fulfilled the Americal College of Rheumatology (ACR) criteria  for the diagnosis of PAN. Post angiogram CT [Figure - 1] b-d revealed multiple nodular hyper dense lesions corresponding to the larger aneurysms seen on cerebral angiography. Serology was negative for c-ANCA and HBsAg while acute phase reactants and liver enzymes were elevated. Diagnosis of PAN was established based on the algorithm proposed by Watt`s et al.  Patient responded to corticosteroids and cycloposphomide during the short follow-up.
A 32-years male was referred for cerebral angiography for an incidental right posterior cerebral artery (PCA) aneurysm detected during CT angiography done for spontaneous right perirenal hematoma [Figure - 4]. He presented to the emergency department two months before for sudden onset left flank pain. CT abdomen done at that time showed a left perirenal hematoma and renal artery pseudo aneurysm which was treated endovascularly [Figure - 4]. He had history of weight loss and grossly deranged renal parameters and the angiography was limited to renal arteries at that time. Digital subtraction angiography (DSA) [Figure - 5] revealed scattered small aneurysms involving visceral arteries, small cerebral aneurysms and a relatively larger aneurysm arising from the hippocampal branch of right PCA. Contrast CT [Figure - 4]c head revealed a nodular lesion in the body region of right hippocampus. Patient fulfilled the diagnostic criteria for PAN which included ACR,  Chapel Hill Consensus Conference (CHCC) criteria  and surrogate/serologic markers. Serology was negative for c-ANCA or HBsAg. He responded to steroid and cycloposphomide and showed weight gain and resolution of fever.
Cerebral vessels may be involved in PAN and patients may present with diffuse encephalopathy, seizure or stroke.  Till 2000 only 19 cases of stroke, both ischemic and hemorrhagic strokes have been documented.  To the best of knowledge till date only four cases, including our first patient, of PAN with intracerebral hemorrhage have been reported. ,
Aneurysms in patients with PAN have commonly been demonstrated in the gastrointestinal system and kidney. [8,9] Intracranial aneurysms are exceptionally rare. ,[ni11],, Documentation of abdominal visceral artery aneurysms are considered characteristic of PAN, especially when the aneurysms are small and multiple. Studies reporting the angiographic spectrum in PAN and its diagnostic utility have mostly not performed cerebral angiography.  The few reports of cerebral involvement in PAN have focused mostly on ischemic events. , Of the nine cases of PAN with intracranial aneurysms reviewed by Oomura et al, only one case had innumerable intracranial aneurysms. The anigraphic findings in both of our patients suggest that multiple small intracranial aneurysms are not uncommon in PAN and cerebral angiography should be included in all the patients of PAN undergoing abdominal angiogram. The suggested treatment for cerebral aneurysms in PAN is conservative.  Kidney involvement is seen in more than 70% of patients with PAN  and changes include infarcts as seen in our first case or uncommonly aneurysm-related hemorrhage as seen in our second case.
The diagnosis of PAN is difficult using both ACR  and CHCC  criteria. Using ACR criteria, many patients qualify to be grouped into more than one disease category, while using CHCC criteria most of the patients do not qualify to be grouped in the PAN category. Inclusion of surrogate and serologic markers in the algorithm ,,, appears to be encouraging but angiography is essential and is relatively specific if numerous micro aneurysms are seen in visceral arteries and probably in the cerebral circulation.
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