Posterior reversible encephalopathy syndrome in a patient with acute intermittent porphyria

Abstract

Sirs: Acute intermittent porphyria (AIP) is an autosomal dominant disorder of heme biosynthesis that can affect the autonomic, peripheral and central nervous system [6]. Posterior reversible encephalopathy syndrome (PRES) is a clinical entity characterized by headache, seizure, conscious disturbance and visual disorder associated with neuroradiological findings, predominantly white matter abnormalities of the parieto-occipital lobes [5]. It has been recognized in a wide variety of conditions, including hypertensive encephalopathy, organ transplantation, uremia, eclampsia and connective tissue disease [1, 3]. However, few reports have described PRES in AIP [2, 4, 7, 8]. A 24-year-old woman presented with abdominal pain, seizure and quadriparesis. The diagnosis of porphyria was confirmed by increased urinary porphobilinogen (78.5 mg/ 24 h; normal 0–2 mg). The urinary and fecal porphyrin profiles were suggestive of AIP. Nerve conduction study demonstrated severe sensorimotor axonal neuropathy. The patient was treated with a high-carbohydrate diet and hematin, which was given intravenously at a dose of 3 mg/ kg of body weight. On the fifth day the patient complained of bilateral visual disturbance. The patient’s visual acuity was decreased to light perception only. The light reflex was preserved. The patient had mildly increased blood pressure (systolic 140–160 mmHg; diastolic 90– 100 mmHg) and tachycardia. Laboratory findings showed a mild increase in liver enzymes and creatinine. Serum electrolytes and osmolarity were normal. Brain MRI demonstrated multifocal high signal intensities in the bilateral occipitoparietal lobe, pons, midbrain, thalamus, basal ganglia, left corona radiata and right frontal lobe on T2-weighted and FLAIR images (Fig. 1a, c). These lesions showed low signal intensity on T1and diffusion-weighed images (DWI). The apparent diffusion coefficient value was increased with 15.1 9 10 mm/s. There was no contrast enhancement. The results of cerebrospinal fluid examination were normal. Tests for connective tissue disorders, paraneoplastic antibodies, viral infections, thyroid function, antithyroid antibodies and antiphospholipid antibodies were all negative. An EEG revealed a generalized slowing in both hemispheres and no epileptiform discharge. The diagnosis of PRES was made on the basis of clinical features and MRI findings. The patient was treated with hematin and strict blood pressure control therapy. Three days after developing visual disturbance, the patient’s visual acuity began to improve and fully recovered. A new MRI performed 2 weeks after the initiation of treatment showed complete disappearance of the lesions (Fig. 1d, f). Cerebral manifestations are unusual in porphyria. Transient and permanent MRI abnormalities have rarely been described in cases of CNS involvement. These lesions are nonspecific with cortical, subcortical and multifocal findings, and can show mild enhancement [7–9]. The pattern of the lesion in our patient was similar to those described as PRES. Typical lesions are usually hypointense or isointense on DWI, with an increase of the apparent diffusion coefficient map, indicating vasogenic edema. The lesions of vasogenic edema in PRES would switch to cytotoxic edema if the precipitating factors were not removed promptly [8]. In our patient, the lesions regressed on the subsequent MRI, and visual acuity fully recovered. S.-Y. Kang (&) J.-H. Kang J. C. Choi J. S. Lee Department of Neurology, College of Medicine, Jeju National University, 1 Ara 1-dong, Jeju-si, Jeju 690-756, South Korea e-mail: neurokang@jejunu.ac.kr