Introduction: Extrapontine myelinolisis is a rare condition caused by severe hydroelectrolytic disorders. Following an initial stage of diffuse encephalopathy, the neurological sequelae are usually of diffuse cognitive deficits and extrapyramidal or cortico-bulbo-spinal disorders. We report a case of extrapontine myelinolisis following hypertonic peritoneal lavage due to rupture of a hydatid cyst of the liver (HCL), which was followed by a syndrome of isolated amnesia due to bilateral hippocampal lesions.
Clinical case: Following rupture of a HCL a 37 year old man was treated by peritoneal lavage with hypertonic saline solution. In the immediate postoperative period he had a prolonged confusion state associated with natremia of 176 mg/dl, which was corrected in less than 24 hours. Seven days later the patient had an apathy-inattention frontal syndrome. Six weeks later, and lasting until three months after operation, he had a selective memory deficit in learning tests (of the Barcelona-PIENC series of tests) with normality (29/30) in the MMST. On magnetic resonance there were hyperintense images in T2 in both hippocampus, insulas and corpus callosum.
Conclusions: Generally caused by rapidly corrected hyponatremia, isolated hyponatremia or hypernatremia may also lead to extrapontine myelinolisis. However, we have found no report of extrapontine myelinolisis due to rupture of HCL and treatment with hypertonic peritoneal lavage. The neurological sequelae of extrapontine myelinolisis are usually global cognitive deficits, extra-pyramidal or cortico-bulbo-spinal disorders. Lesions seen on MR are usually found in the basal ganglia, thalamus or corpus callosum (with or without involvement of the pons). We have found no descriptions of bilateral hippocampal lesions causing selective memory deficits in this condition. Treatment by hypertonic peritoneal lavage for ruptured HCL may cause severe hydro-electrolytic alterations which may lead to myelinolisis of the CNS. We report of a case with bilateral hippocampal lesions and selective memory deficit, not previously described within the clinical spectrum of extrapontine myelinolisis.