WATCH: 'Sleeping' Saudi prince moves hands after 15 years in coma
Prince Al-Waleed bin Khalid Al-Saud moved his hand in response to someone conversing by his bedside, a video that emerged online showed.
"Hello, hi," the person says to the prince, prompting him to lift two fingers.
"Let me see, higher, higher!" she says in a successful attempt to encourage more movement.
The last time such movement took place was five years ago in 2015.
Prince Al-Waleed has been on a ventilator since 2005 after suffering a brain haemorrhage during a car accident while studying at a military college.
His father, the brother of billionare Saudi business tycoon Prince Al-Waleed bin Talal Al Saud, has refused to give up on his son and insists on monitoring his condition with hopes that he may one day wake up.
Prince Khalid was among those detained for 11 months for criticising a crackdown on the kingdom's elite that saw dozens of princes, officials, and tycoons imprisoned at Riyadh's Ritz-Carlton hotel in 2017.
He was re-arrested briefly the following year.
Hopes in the UAE
Last year, an Emirati woman woke up after a 27-year-long stupor.
Munira Abdulla fell into a coma after a life altering car accident in 1991 left her with a serious brain injury.
Her decades-long treatment took her from one hospital to the next, where doctors held out little hope for her recovery.
"I never gave up on her because I always had a feeling that one day she will wake up," her son Omar Webair, 32, told The National.
Webair believes an argument in his mothers hospital room in Germany brought her out of her comatose state.
Abdulla was transferred from the UAE to Germany in 2017 to receive more comprehensive treatment.
Webair described the car accident, which occurred when he was four in Al-Ain, Abu Dhabi, to The National.
His mother and uncle were taking him home from school when their car was hit by a school bus.
"My mother was sitting with me in the back seat. When she saw the crash coming she hugged me to protect me from the blow," Webair said.
Webair and his uncle walked away with light injuries, but Abdulla was brought to the hospital where she was declared to be in a minimally conscious state.
Webair would walk four kilometres every day to sit with his mother and speak to her - impairing his ability to hold down employment.
"I never regretted it. I believe that, because of my support for her, God saved me from bigger troubles."
The UAE Crown Prince Court gave the family a grant for Abdullah to be treated in Germany in April 2017, where she underwent surgeries to aid her deteriorating muscles and was given treatment to improve sleep rhythm and wakefulness.
"Our primary goal was to grant her fragile consciousness the opportunity to develop and prosper within a healthy body, just like a delicate plant which needs good soil to grow," a neurology expert and Abdulla's doctor in Germany, Dr Ahmad Ryll, told The National.
The treatment led to improvement in her condition and it seemed Abdulla was able to sense her doctors and children in the room.
"I told the doctors I was expecting her to start talking again, they told me: 'you are running wild with your imagination, we are only doing rehabilitation to fix her quality of life'," said Webair.
In Abdulla's last week of treatment in Germany, an argument occurred in her hospital room and Webair noticed his mother making strange sounds. Three days later, Webair awoke to the sound of her calling his name.
"It was her! She was calling my name, I was flying with joy; for years I have dreamt of this moment, and my name was the first word she said."
The family then returned to Abu Dhabi where Abdulla, now in her 60s, is receiving ongoing physiotherapy and rehabilitation treatment.
She is "currently able to communicate with self and surrounding in a very reasonable manner especially in familiar situations", Mafraq Hospital said in a statement last month.
"The reason I shared her story is to tell people not to lose hope on their loved ones; do not consider them dead when they are in such a state," said Webair.