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NEURORADIOLOGY Table of Contents   
Year : 1999  |  Volume : 9  |  Issue : 4  |  Page : 183-186
Primary angiitis of central nervous system : Unusual MR imaging features


Department of Radiodiagnosis and Imaging Christian Medical College and Hospital, Vellore, Tamil Nadu, India

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Keywords: Primary Angiitis, Central Nervous system, MR

How to cite this article:
Singh S. Primary angiitis of central nervous system : Unusual MR imaging features. Indian J Radiol Imaging 1999;9:183-6

How to cite this URL:
Singh S. Primary angiitis of central nervous system : Unusual MR imaging features. Indian J Radiol Imaging [serial online] 1999 [cited 2020 Jul 4];9:183-6. Available from: http://www.ijri.org/text.asp?1999/9/4/183/28350
Primary angiitis is a rare disorder of the central nervous system, of unknown etiology, characterized by a non-specific granulomatous inflammation of the media and adventitia of small parenchymal and leptomeningeal arteries and veins [1],[2],[3]. However, any cerebral vessel may be involved [1],[2],[3]. It results in cerebral ischemia with resultant neurological dysfunction that remains unexplained even after thorough clinical and laboratory evaluation. Primary angiitis of the central nervous system (PACNS) is usually seen in middle-aged individual with no sex predilection. Symptomatology is variable and usually presents as headache, focal or global neurological dysfunction, confusion, intellectual deterioration, memory loss, malaise, stroke, encephalopathy or seizures [1],[2],[3]. Fever, myalgia, arthralgia and arthritis may also occur. A raised ESR and CSF pleocytosis with increased protein levels may be seen. The criteria for establishing a definitive ante-mortem diagnosis include clinical presentation, angiographic findings, exclusion of systemic inflammation and infection and leptomeningeal or parenchymal biopsy, which is a gold standard [3]. The imaging findings may resemble acute disseminating encephalomyelitis, stroke, atypical primary CNS lymphoma, myelinoclastic diffuse sclerosis, toxic exposure and encephalitides [4],[5]. The diagnosis is based on the exclusion of these diseases. This study demonstrates very uncommon MR findings, which to our knowledge have not been previously described.


   Case Report Top


An eighteen-years-old man was admitted with a three weeks history of severe holocranial headache, high-grade intermittent fever and progressive loss of vision in both eyes. His word output was reduced and he developed spasticity of all four limbs. On examination he was febrile, had stable vital signs and a Glasgow Coma Scale of 15/15 but he was withdrawn and had a reduced attention span. There was no cranial nerve dysfunction or sensory impairment. Multi-mode evoked potential and nerve conduction studies showed evidence of dysfunction of both optic nerves and dorsal cord. Other systems were unremarkable. Routine and special laboratory work-up of blood, CSF, urine and bone marrow for fungal, viral, bacterial and demyelinating causes were normal, except for mild CSF lymphocyte pleocytosis with elevated protein and sugar. EEG showed focal slow wave disturbances restricted to the right posterior temporal, temporal parietal and occipital regions. In view of the clinical presentation and MR findings, a provisional diagnosis of acute disseminating encephalomyelitis was arrived at. He was treated with high doses of intravenous methyl prednisolone. However his condition deteriorated with worsening of this sensorium. He developed generalized tonic-clonic seizures and decorticated positioning. Plasmapheresis was carried out, but was discontinued due to bleeding diathesis. Sereotactic brain biopsy was done; but the report was inconclusive. He was also treated with intravenous immunoglobulin and acyclovir. His condition improved slightly and then plateaued. An open brain diopsy of the right frontal lobe was then performed, which confirmed the diagnosis of primary angiitis.


   Discussion Top


MR imaging showed multiple, high signal intensity lesions on T2 and proton density weighted images in the cortex, subcortical white matter and basal ganglia. There were no infratentorial lesions and the periventricular white matter, thalami and midbrain were normal [Figure - 1] There were no infratentorial lesions and the periventricular white matter, thalami and mid-brain were normal. There was no enhancement of the lesions. On T1W images, the basal ganglia lesions were of low signal intensity and the other lesions were isointense. A repeat MR after one week showed older lesions more intense, confluent and symmetrical in distribution with the appearance of new lesions in the periventricular white matter, thalami and midbrain [Figure - 2]. A repeat MR after 3 weeks showed mild regression in the size of the cortical and subcortical white matter lesions. The lesions in the thalami, midbrain and basal ganglia appeared larger [Figure - 3].

The MR findings in PACNS are variable and with no characteristic pattern; hyperintense foci representing ischemia or infarction in the cortex, subcortical and deep white matter and at the corticomedullary junction on T2W images, strokes of varying sizes, parenchymal hemorrhages and brainstem lesions may be seen [3]. The common findings are bilateral, multiple supratentorial infarcts involving both the gray and white matter, predominantly in the deep white matter including the corpus callosum and capsular tract [1],[5]. Less commonly, it presents as primary parenchymal hemorrhage or simulates primary a brain tumor [1],[2],[3],[6],[7]. Nishikawa et al reported one study with multiple visible and vanishing aneurysms in a patient who had recurrent intracerebral hemorrhage [8]. MR features resembling demyelinating disease have been reported [5]. Lesions mimicking leuco-encephalopathies and leucodystrophies limited to case reports have been reported and occur late in the course of disease in association with deep gray matter involvement or distinguishing enhancing characteristics [5]. As seen in this patient, all lesions are supratentorial in location [1]. No lesions in the infra-tentorium are found [1],[2],[3]. However, Shoemaker et al reported one study with both supra and infratentorial lesions [3]. New lesions may appear on follow up studies and other preexisting lesions may decrease in prominence or disappear [3], as in our patient, where lesions in the cortex decreased in size and new lesions appeared in the thalami, mid brain and periventricular white matter. On T1W images, the basal ganglia lesions were of low signal intensity, however, the other lesions were isointense [Figure - 1]c. There was no enhancement of the lesions. Although in our patient, we did not observe enhancement, the pattern of enhancement may be variable with irregular subcortical streaks, leptomeningeal enhancement with little parenchymal involvement, focal cortical ribboning or diffuse parenchymal vessel enhancement [3],[5]. Shoemaker et al reported a case with numerous punctate areas of enhancement in the brain stem, cerebral and cerebellar white matter [3]. In our patient, angiography was not advised, as angiitis was not suspected. The sensitivity of MR and cerebral angiography is debated. Greenan et al have reported studies with positive findings on angiography and normal MR images [1]. However, Harris et al insisted that if a high quality MR is obtained, a negative MR does more to exclude the possibility of intracranial angiitis than does cerebral angiography [2]. Shoemaker et al reported a case, which showed non-specific findings on MR with normal cerebral angiography [3]. A leptomeningeal and brain biopsy is certainly warranted if there is no cause to explain a clinical syndrome of encephalopathy prolonged over days or weeks, especially with local cerebellar signs and a raised CSF protein and pleocytosis, with or without suggestive signs of vasculitis on brain MR or angiography. There are even reports of vasculitis being reported on post-mortem when previous biopsy was negative [3]. Brain biopsy from cortical tissue and leptomeninges should be taken to avoid sample errors due to skip lesions [3]. In conclusion, the MR appearance in PACNS is variable. If clinical criteria fail to establish a diagnosis in a patient with MR findings of bilateral symmetrical confluent lesions in the cortical, subcortical, periventricular, basal ganglia, thalamic and midbrain locations; a differential diagnosis of PACNS should also be considered and a brain biopsy should be advised for a definitive diagnosis.

 
   References Top

1.Greenan T J, Grossman RI, Goldberg HI. Cerebral vasculitis: MR imaging and angiographic correlation, Radiology 1992; 182,65-72.   Back to cited text no. 1    
2.Harris KG, Tran DD, Sickels WJ, Cornell SH and Yuh WTC. Diagnosing intracranial vasculitis: The role of MR and Angiography. AJNR 1994; 15: 317-330.   Back to cited text no. 2    
3.Shoemaker EI, Lin ZS, Rae-Grant AD and Little B. Primary angiitis of central nervous system: Unusual MR appearance. AJNR 1994; 15: 331-334.   Back to cited text no. 3    
4.Alhalabi M, Moore PM. Serial angiography in isolated angiitis of central nervous system. Neurology 1994; 44: 1221-1226.   Back to cited text no. 4  [PUBMED]  
5.Finelli PF, Onyuke HC, Uphoff DF. Idiopathic granulomatous angiitis of the CNS manifesting as diffuse white matter disease. Neurology 1997; 49: 1696-1699.   Back to cited text no. 5    
6.Cravioto H, Feigin I. Non-infectious granulomatous angiitis with a predilection for the nervous system. Neurology 1959; 9: 599-609.   Back to cited text no. 6  [PUBMED]  
7.Johnson M, Maciunas R, Dutt P, Clinton ME, Collin R. Granulomatous angiitis masquerading as a mass lesion. Surg Neurol 1989; 31: 49-53.   Back to cited text no. 7    
8.Nishikawa M, Sakamoto H, Katsuyama J, Hakuba A, Nishimura S. Multiple appearing and vanishing aneurysms: primary angiitis of central nervous system. Case report. J Neurosurg 1998; 88: 133-137.  Back to cited text no. 8    

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Correspondence Address:
Surendra Singh
Department of Radiodiagnosis and Imaging Christian Medical College and Hospital, Vellore-632 004, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


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