Police rescued Jahanara Begum Rosy, 45, a former teacher of Dhaka's Viquarunnisa Noon School and her son Mehedi Islam Jimun from a house at the town's Rampur area Wednesday evening.
Local administration and police said that a raid was conducted after a local newspaper reported the confinement.
Eleven-year-old Jimun wrote a note pleading to rescue them and slid it outside through a closed window, which was found by a local and handed over to the newspaper.
The mother and son have been admitted to the Feni Sadr Hospital after being rescued on Wednesday.
Rosy is suffering from mental illness while her son Jimun is limping due to Ricket disease, said the hospitals Resident Medical Officer Asim Kumar Saha.
He suspects the mother might have developed Schizophrenia because of being held captive in a small room for five years.
Her brother-in-law Nuru Islam said that Rosy, who has done her Master’s in Bangla from the Dhaka University (DU), used to teach at the Viquarunnisa Noon School and College in Dhaka.
In 2000, she married one Abul Kalam Azad Bhuiyan, also a DU graduate, but they were divorced after three years. Rosy then moved to her parent's house in Feni.