[Clinical features and neuroimaging findings of 12 patients with acute disseminated encephalomyelitis involved in corpus callosum].

OBJECTIVE: To summarize the clinical features and neuroimaging findings of the patients with acute disseminated encephalomyelitis (ADEM) involved in corpus callosum (CC) so as to distinguish it from other diseases.

METHODS: A total of 12 ADEM patients with the involvement of CC during the period of 2010-2012 were recruited. There were 9 males and 3 females with a mean age of 31±14 years (range: 10-54). Their clinical and neuroimaging features were retrospectively reviewed and all data analyzed by SPSS 18.0.

RESULTS: (1) All of them had an acute or subacute onset. Two patients had a history of vaccination and 5 suffered upper respiratory tract infection or diarrhea. (2) The presenting symptoms included fever (n=5), headache (n=4), unsteady gait (n=2), urinary retention (n=1), indifference (n=1) and delirium (n=1). (3) The main clinical symptoms included memory loss (n=9), delirium (n=5), somnolence (n=4), urinary retention (n=9), paraplegia (n=4) and unsteady gait (n=5). (4) The examinations of cerebrospinal fluid (CSF) revealed increased intracranial pressure (n=4), leucocytosis (n=3) and increased protein (n=7) of 7 cases. All oligoclonal bands were negative. (5) The lesions were involved in bilateral CCs in 12 patients. Among them, splenium was the most commonly affected (n=9), secondly stem (n=5) and lastly genu (n=4). For 6 patients, the intracranial lesions were all in their CCs. And among them, 2 cases were involved in spinal cord. Except for CC, there were other focal lesions in brain stem and cerebellum (n=4) and spinal cord (n=6). (6) On magnetic resonance imaging (MRI), all cases showed long T2 signal intensity with blurred images. And among them, 2 cases' lesions in brain were discerned only by diffuse weighing imaging (DWI) or T2 fast fluid-attenuated inversion recovery (T2FLAIR) instead of T2-weighted. The lesions of CCs showed on gadolinium-enhanced MRI were significantly enhanced and the shapes were sheet-like (4/6). Spinal cord lesions was found in 6 cases and most spinal cord lesions were discontinuous. And the number of spinal cord segments with lesions was from 4 to 8. The shapes of lesions of spinal cord showed on enhanced MRI were like thin line. (7) Most of them were misdiagnosed as viral encephalitis (n=5), tuberculous meningoencephalitis (n=1) and brain neoplasms (n=2). And another case was admitted into urology surgery ward due to urinary retention.

CONCLUSION: There are three key points about the characteristics of the ADEM patients with CC lesions: (1) They may have an adult male preponderance. The distinctive symptoms include fever, headache, delirium, somnolence, memory loss, unsteady gait and urination disorders, etc.. (2) The number of lesions on brain MRI can be multiple or single, especially the lesions of CC (mostly in splenium). On MRI, all cases showed long T2 signal intensity with blurred images so that DWI and T2 FLAIR may have a higher efficiency of detecting the lesions. In particular, multiple lesions may be all enhanced or not enhanced at equal pace on enhanced MRI. (3) In ADEM patients with CC lesions, many indices of CSF chemical examination, such as increased intracranial pressure, leucocytosis, increased protein, low sugar and low chloride, indicate the presence of intracranial infective diseases. Therefore they are most likely to be misdiagnosed as viral encephalitis or tuberculous meningoencephalitis. However, CC is not the predilection site for viral encephalitis since CC belongs to white matter but not gray matter. So ADEM should be a more appropriate diagnosis for these cases.