When it comes to microsurgical skills required for nerve repair, Alastair is at the head of the field.
Even during routine surgery, several nerves are at risk. Injury to these nerves can occur following oral surgical procedures, particularly wisdom tooth surgery (1-5% of procedures), orthognathic jaw surgery (around 10%) and occasionally following local anaesthetic injections or blocks.
Commonly injured nerves include the lingual nerve which carries sensation (or feeling) from the tongue or the Inferior alveolar nerve which gives sensation to the lower lip and chin.
Symptoms can be extremely distressing for some patients, and range from anaesthesia (complete loss of feeling) to paraesthesia (altered feeling / pins and needles) or less commonly dysaesthesia (painful sensations).
The lowdown: lingual nerve injuries
Common indicators for surgical exploration and repair
- Complete transection confirmed clinically – unfortunately this is often not realised at the time of surgery.
- No improvement in sensation after 3 months, or evidence of neuroma formation
- Persistent severe unpleasant sensations and pain
- Patient’s quality of life significantly affected
Expected outcomes following surgical repair
The evidence suggests that earlier repairs lead to better outcomes… though nerve repairs can be beneficial even after a few years.
It’s important to be aware that outcomes for nerve repair vary between patients.
From the published data, the overall success rate shows improvements for 60-80% with nerve repair.
How timing affects outcomes:
- Early repair (less than 3 months): better outcomes
- Delayed repair (more than 6 months): a reduced success rate. Some results in the literature suggest good outcomes with surgery performed even beyond a year post-injury.
Pain outcomes:
- Resolution of neuropathic pain: 60-70%
- Persistent symptoms: 30-40%
Sensory recovery:
- Complete recovery: 25-30%
- Partial improvement: 35-50%
- No improvement: 20-40%
Taste function:
- Variable recovery
- Often incomplete return of taste sensation
Again, bear in mind that improvements in quality of life are reported in 60-80% of cases.
A closer look
When a nerve is cut (transected), several changes occur in your body. The nerve is made up of many fibres that normally carry signals between your brain and different parts of your body. After the cut, the end of the nerve tries to heal itself by growing new nerve fibres. Sometimes, these growing nerve fibres can become tangled and form a small, ball-like growth called a neuroma.
Neuromas can be painful because:
- They contain many sensitive nerve endings
- They can be easily irritated by pressure or touch
- These nerve endings can send incorrect pain signals to your brain
- The area around the neuroma can become inflamed
The pain from neuromas is often described as burning, shooting, or electric-shock like. Sometimes even light touch in the area can trigger significant discomfort.
Image credits: Dr Ann Sandison – Consultant Pathologist, Guys and St Thomas
Case Studies
Case Study 1
A patient came referred to see Mr Fry suffering with pain and numbness to the right side of his tongue after having his lower wisdom teeth removed 6 months previously. The symptom of numbness had been presented immediately after waking up and not improved. The pain had gradually worsened requiring painkillers. He was informed at the time that the surgery was quite tricky and that the tooth had to be divided.
Over the course of 6 months he had no improvement, no sensation to touch, temperature or taste on the right side of the tongue. He had been prescribed Pregabalin, which had not really improved things and had been taking vitamin supplements. The pain was fairly constant in the area but with certain areas that were extremely painful to touch (dysaesthesia).
Clinical examination revealed anaesthesia (loss of sensation) to the right side of the tongue along the distribution of the lingual nerve to light touch and pin prick stimulus. There were areas that light touch would stimulate and trigger painful sensation.
Over a period of 2 months of observation there had been no further improvement, and so after weighing up the options a decision was made to go ahead with surgery to explore the nerve and repair as necessary.
Surgery was carried out under a short general anaesthesia lasting around an hour and a half. A small cut was made inside the mouth around the teeth on the affected side and the nerve exposed in the floor of the mouth. The nerve was examined under an operating microscope and found to have been divided or cut, with some intervening hard scar tissue which had developed in the gap between the ends of the nerve where it had been injured. This was in the area of the wisdom tooth. The scar tissue was excised (removed) and sent to the pathologist – this was reported as showing fragments of bone and scar tissue.
The nerve was then carefully cleaned and the ends freshened up and rejoined (anastamosed) directly with a small stitch under high powered magnification. The wound was then washed with saline and closed with dissolving stitches.
Soft diet was commenced immediately, antibiotics given at the time as well as pain killers to cover the first few days.
Review at 2 months showed some reduction in pain and a feeling of slightly improved sensation.
At around 1 year, the nerve pain experienced had fully resolved and sensation was virtually normal. There was still some mild reduction in reported taste on that side of the tongue.
Patient Feedback
“Sensation has improved to nearly normal, and is still improving. The pain has improved was intermittent post surgery but now background pain is much improved.”
Case Study 2
Patient underwent wisdom tooth surgery with a “lingual split” procedure under general anaesthetic to remove impacted lower wisdom tooth. Patient found that on waking he was numb to the left side of the tongue and this did not improve.
The patient also had pain affecting the the left tongue and in to the lingual sulcus. There was also a trigger point of pain near the gum adjacent to the surgical site, which caused shooting pain.
After a period of a few months of observation with no improvement, a surgical procedure was undertaken to expose the nerve with a view to performing a nerve repair.
Findings & Treatment
Lingual nerve neuroma was identified at the surgical site – this was causing symptoms of numbness and pain along the path of the nerve to the tongue.
The lingual neuroma was excised. The nerve was then repaired under high powered magnification.
Citations
- Zuniga JR, et al. Surgical management of trigeminal nerve injuries: outcomes of repair and reconstruction. J Oral Maxillofac Surg. 2017
- Bagheri SC, et al. Microsurgical repair of peripheral trigeminal nerve injuries. J Oral Maxillofac Surg. 2012
- Robinson PP, et al. Current management of damage to the inferior alveolar and lingual nerves as a result of removal of third molars. Br J Oral Maxillofac Surg. 2004
- Susarla SM, et al. Does early repair of lingual nerve injuries improve functional sensory recovery? J Oral Maxillofac Surg. 2015