Patients with facial paralysis such as Bell’s palsy have recovered movement after a physiotherapist found that stretching the inside of their mouths with her finger did the trick.

The low-tech solution was discovered by specialist neurological physiotherapist Lorraine Clapham at Southampton General Hospital.

The discovery gives hope to patients who suffer from facial palsy, where damage to nerves caused by injury, surgery or unexplained syndromes cause muscles to weaken and droop.

The most common cause of facial paralysis is Bell’s palsy, which accounts for about 23 cases per 100,000 people and, although most make a good recovery, some are left with a muscle weakness.

By stretching the inside of the cheeks of several patients with complete facial nerve palsy with a finger while performing routine checks for ulcerations or trauma, Dr Clapham caused the paralysed facial muscles to move – something not seen before.

The breakthrough, reported in the Journal of Laryngology & Otology, was named Clapham’s sign in her honour.

The procedure is under further investigation but it is believed it may help maintain muscle metabolism and prevent wastage to kick-start movement in patients struck by a syndrome, or help patients who have undergone surgery make a quicker recovery.

Dr Clapham said: “The presence of this sign may be an important indicator regarding the recovery of the facial nerve and movements of the face.

“It may also help surgeons decide if and when surgery should be offered to try and restore facial movements.”

The patients’ responses took a minimum of six to seven weeks to appear after injury or surgery and continued for up to seven months following the nerve damage.