Plasmapheresis improves the outcome of central pontine myelinolysis

Abstract

Sirs: Central pontine myelinolysis(CPM) is a demyelinating diseaseof the pons rarely involving otherareas of the central nervous sys-tem. The etiology and the patho-genesis of CPM remain unclear,though aggressive osmolar correc-tion and in particular rapid correc-tion of hyponatr emia are the mainfactors in treating patients at risk.There is no specific therapy ofchoice.Several uncontrolled thera-peutic trials have led to a substan-tial improvement of the prognosiswhich had always been deemeduniformly bad [1].Bibl etal.suc-cessfully treated three young fe-male patients with extensive thera-peutic plasmapheresis soon afterthe diagnostic confirmation ofCPM by magnetic resonance imag-ing [2].All patients had undergonecorrection of severe hyponatremiathree to five days before the onsetof neurological symptoms com-prising a rapidly evolving flaccidquadriplegia with dysphagia anddysarthria.Significant clinicalimprovement was obtained onemonth after plasmapheresis andneurological examination one yearlater disclosed partial recovery upto total remission in one patient.The assumption is that undefinedmyelin toxic compounds releasedby the osmotic stress contribute tothe irreversible demyelinatingprocess in CPM and that therapeu-tic plasmapheresis may reducehigh-molecular myelin toxic sub-stances leading to clinical improve-ment.We report another case ofCPM dramatically improved byplasmapheresis started a week afterthe onset of neurological symp-toms.A 59-year-old woman with ahistory of mild alcohol abuse andmild hypertension treated by athiazid diuretic gradually devel-oped general malaise followed bymotor weakness and mental slow-ness. Within two weeks the patientbecame lethargic and was admit-ted to hospital. Blood tests re-vealed severe hyponatremia(113mmol/L) that was rapidlyadjusted over three days to normalvalues by infusing hypertonicsaline, but remaining within atarget volume not above 10Meq/L/24 hours. Correction ofhyponatrem ia resulted in a com-plete recovery of mental status andmotor function. Three days afterrecovering, the patient’s conscious-ness rapidly deteriorated again. Ina few days she developed slurredspeech, dysphagia for liquid foodsand legs weakness. A week laterneurological examination dis-closed pseudobulbar palsy withflaccid tetraplegia associated withdeep-tendon hyperreflexia, patho-logical crying, impairment ofocular movements, anarthria anddysphagia. Magnetic resonanceimaging (MRI) performed onadmission showed an area ofhyperintensity in the central ponson T2-weighted images suggestiveof CPM (Fig.1). Ten consecutivetherapeutic plasmapheresis ses-sions were started with two tothree sessions a week for onemonth with a total of 37300 mLplasma exchanged with albumin3% and crystalloids. Significantclinical improvement began tendays after plasmapheresis (Fig.2)continuing until intensive rehabili-tation was possible. Eight monthslater, a mild tetraparesis with theability to walk unaided, slightdysphonia and dysarthria weredetected on neurological examina-tion. Despite clinical improvement,the pontine lesion and signalhyperinten sity on MRI T2-weighted images appeared to beunmodified. The positive outcomein our patient and the strong tem-poral link between treatment onsetand clinical improvement, supportthe hypothesis of plasmapheresisas an effective treatment for CPM.However, t he possibility of a spon-taneous good outcome cannot beexcluded [3].Because of the severity of theneurological deficits especially inthe acute phase and the possibilityof a poor prognosis up to death,prompt,safe and apparently effec-tive treatment wi th plasmapheresisshould be considered once CPM isdiagnosed.