General (retd) Musharraf, 75, who has been living in Dubai since March 2016, is facing the treason case for suspending the Constitution in 2007, a punishable offence for which he was indicted in 2014.
A conviction for high treason carries the death penalty or life imprisonment.
Siddiqui informed about Musharraf's illness in October last year, saying the former president's disease has "weakened his nervous system". At the time, he was being treated for the condition in London.
"Due to amyloidosis, broken protein starts getting deposited in various organs," Siddiqui said. "[As a result] Pervez Musharraf has difficulty in standing and walking."
Amyloidosis is a rare disease that occurs when a substance called amyloid builds up in a person's organs. Amyloid is an abnormal protein that is produced in the bone marrow and can be deposited in any tissue or organ.
Amyloidosis can affect different organs in different people. Amyloidosis frequently affects the heart, kidneys, liver, spleen, nervous system and digestive tract. Severe amyloidosis can lead to life-threatening organ failure.
The APML official had then said that Musharraf's treatment could continue for up to five or six months.
Upon his full recovery, Siddiqui had said, Musharraf intends to return to Pakistan.