Neurological complications of acute intermittent porphyria.

BACKGROUND: Acute intermittent porphyria (AIP) is an inherited disorder of heme biosynthesis, the clinical manifestations of which are incompletely understood. In this report, we describe 12 cases of AIP, focusing on the neurological manifestations.

METHODS: Twelve patients were diagnosed with AIP on the basis of characteristic clinical findings, erythrocyte porphobilinogen deaminase (PBGD) activity, and molecular genetics. Central and peripheral nervous system manifestations were noted, and electrophysiological and radiological studies performed. Potential precipitating factors were recorded.

RESULTS: Eleven PBGD gene mutations were identified in 12 patients. Nine patients experienced neurological symptoms involving the central nervous system (consciousness disturbance, n = 8; convulsion/seizure, n = 4; behavior change, n = 1), while 7 patients experienced peripheral neuropathies (motor paresis, n = 7; impairment of bulbar or respiratory function, n = 4). The electrophysiological and electroencephalographic findings were consistent with the neurological symptoms of AIP. Urinary PBG and δ-aminolevulinic acid levels were elevated in all patients. PBGD enzyme activity levels were below normal in all patients. Eight patients had documented exposure to porphyrogenic agents.

CONCLUSIONS: Our detailed description of a relatively large number of cases of AIP may help clinicians to recognize this often difficult-to-diagnose disorder.