My Mother aged about 65 years suffered a mild stroke 2 months back .She was admitted to hospital for 17 days and was on ventilation support for 7 days. She was also diagnosed for low sodium count was around 102. She recovered from sodium count now at around 140. Now she is on oxygen support her blood oxygen level reduced to 80 to 90 with out oxygen support. While sitting oxygen level fluctuate from 80 to 92 but while sleeping level goes down to 77-85. Part of her MRI report of brain :- PRESENT MR REVEALS DIFFUSELY INCREASED SINGLE ON T2 & STAIR SEQUENCES INVOLVING THE BILATERAL BASAL GANGLIA & THALAMI ON EITHER SIDE WITH OUT SIZABLE MASS EFFECT-LIKELY TO BE DUE TO OSMOTIC DEMYELINATION DUE TO METABOLIC IMBALANCE (EXTRAPONTINE MYELINOLYSIS) ASSOCIATED WITH PERIVENTRICULAR ISCHEMIC LESIONS OF VARYING STAGES, ISCHAEMIC PONTINE GLIOSIS & HTN INCDUCED LEUKOARIAOSIS .NO ICH IS SEEN. She was advised for sleep study test by the Pulmonologist. Her sleep study report suggests that the average oxygen saturation of the patient was 84% and the lowest 71% during sleep. IMPRESSION: - Mild OSAHS.ADVISE:- CPAP Trial. Sir, presently our neurologist prescribed Tab CITISTAR PM AND DONAMEM 5.We want to know that is this treatment is on right direction. Please give your opinion about above mentioned medicines. I would like to know the reasons for this low blood oxygen level. Regards