Abstract: Objective To elucidate the neuroimaging changes and clinical relevances of acute intermittent porphyria (AIP) patients with neurological symptoms by analyzing the clinical features and neuroimaging findings. Methods 30 cases of AIP were described, focusing on their neurological clinical features and neuroimaging findings. Urinary porphobilinogen (PBG) was quantitatively screened using the Watson-Schwartz method. During porphyric attacks, brain computed tomography (CT) and/or magnetic resonance imaging (MRI) as well as electroencephalography blood sodium levels and cerebrospinal fluid (CSF) examinations were performed in some patients. Genetic screening for AIP was also performed in families who consented to genetic testing. Molecular genetic analysis of the hydroxy-methylbilane synthase (HMBS) was conducted by direct sequencing of peripheral blood samples. Results 30 AIP patients were all females, and the clinical manifestations were various, including consciousness disturbance (n=18), convulsion (n=17), muscle weakness (n=14), abdominal pain (n=29) and tachycardia (n=21). Based on the neuroimaging, two porphyric encephalopathy (cortical laminar necrosis), four posterior reversible encephalopathy syndrome (PRES), four osmotic demyelination syndromes (ODS) and one reversible splenial lesion syndrome (RESLES) were identified. The blood sodium levels of abnormal MRI/CT group were significantly lower than that of normal MRI/CT group[(110.8±6.5)mmol/L vs. (118.4±7.8)mmol/L, P＜0.01].25 cases of pathogenic mutations were detected. Conclusions Cortical laminar necrosis, PRES, ODS, and RESLES represent patterns of central nervous system(CNS) involvement in AIP. Hyponatremia may be an important mechanism in porphyric encephalopathy.

Key words: acute intermittent porphyria, neuroimage, hyponatremia, prognosis