The main question addressed by this review is how effective are different treatments and what are the best timings for these treatments following accidental damage during surgery to the nerves that supply sensation to the tongue, lower lip and chin.
The nerves (alveolar and lingual) supplying sensation to the tongue, lower lip and chin, may be injured as a result of surgical treatments to the mouth and face, including surgery to remove lower wisdom teeth. The vast majority (90%) of these injuries are temporary and get better within eight weeks. However if they last for longer than six months they are considered to be permanent. Damage to these nerves can lead to altered sensation in the region of the lower lip and chin, or tongue or both. Furthermore, damage to the nerve supplying the tongue may lead to altered taste perception. These injuries can affect people's quality of life leading to emotional problems, problems with socialising and disabilities. Accidental injury after surgery can also give rise to legal action.
There are many interventions or treatments available, surgical and non-surgical, that may enhance recovery, including improving sensation. They can be grouped as.
1. Surgical – a variety of procedures.
2. Laser treatment – low-level laser treatment has been used to treat partial loss of sensation.
3. Medical – treatment with drugs including antiepileptics, antidepressants and painkillers.
4. Counselling – including cognitive behavioural and relaxation therapy, changing behaviour and hypnosis.
The Cochrane Oral Health Group carried out this review, and the evidence is current as of 9 October 2013. There are two studies included, both published in 1996, which compared low-level laser treatment to placebo or fake treatment for partial loss of sensation following surgery to the lower jaw. There were 15 participants in one study and 16 in the other, their ages ranging from 17 to 55 years. All had suffered accidental damage to nerves of the lower jaw and tongue causing some loss of sensation following surgery.
Low-level laser therapy was the only treatment to be evaluated in the included studies and this was compared to fake or placebo laser therapy. No studies were found that evaluated other surgical, medical or counselling treatments.
There was some evidence of an improvement when participants reported whether or not sensation was better in the lip and chin areas with low-level laser therapy. This is based on the results of a single, small study, so the results should be interpreted with caution.
No studies reported on the effects of the treatment on other outcomes such as pain, difficulty eating or speaking or taste. No studies reported on quality of life or harm.
Quality of the evidence
The overall quality of the evidence is very low as a result of limitations in the conduct and reporting of the two included studies and the low number of participants, and evidence from participants with only partial sensory loss.
There is clearly a need for randomised controlled clinical trials to investigate the effectiveness of surgical, medical and psychological interventions for iatrogenic inferior alveolar and lingual nerve injuries. Primary outcomes of this research should include: patient-focused morbidity measures including altered sensation and pain, pain, quantitative sensory testing and the effects of delayed treatment.
Iatrogenic injury of the inferior alveolar or lingual nerve or both is a known complication of oral and maxillofacial surgery procedures. Injury to these two branches of the mandibular division of the trigeminal nerve may result in altered sensation associated with the ipsilateral lower lip or tongue or both and may include anaesthesia, paraesthesia, dysaesthesia, hyperalgesia, allodynia, hypoaesthesia and hyperaesthesia. Injury to the lingual nerve may also affect taste perception on the affected side of the tongue. The vast majority (approximately 90%) of these injuries are temporary in nature and resolve within eight weeks. However, if the injury persists beyond six months it is deemed to be permanent. Surgical, medical and psychological techniques have been used as a treatment for such injuries, though at present there is no consensus on the preferred intervention, or the timing of the intervention.
To evaluate the effects of different interventions and timings of interventions to treat iatrogenic injury of the inferior alveolar or lingual nerves.
We searched the following electronic databases: the Cochrane Oral Health Group's Trial Register (to 9 October 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 9), MEDLINE via OVID (1946 to 9 October 2013) and EMBASE via OVID (1980 to 9 October 2013). No language restrictions were placed on the language or date of publication when searching the electronic databases.
Randomised controlled trials (RCTs) involving interventions to treat patients with neurosensory defect of the inferior alveolar or lingual nerve or both as a sequela of iatrogenic injury.
We used the standard methodological procedures expected by The Cochrane Collaboration. We performed data extraction and assessment of the risk of bias independently and in duplicate. We contacted authors to clarify the inclusion criteria of the studies.
Two studies assessed as at high risk of bias, reporting data from 26 analysed participants were included in this review. The age range of participants was from 17 to 55 years. Both trials investigated the effectiveness of low-level laser treatment compared to placebo laser therapy on inferior alveolar sensory deficit as a result of iatrogenic injury.
Patient-reported altered sensation was partially reported in one study and fully reported in another. Following treatment with laser therapy, there was some evidence of an improvement in the subjective assessment of neurosensory deficit in the lip and chin areas compared to placebo, though the estimates were imprecise: a difference in mean change in neurosensory deficit of the chin of 8.40 cm (95% confidence interval (CI) 3.67 to 13.13) and a difference in mean change in neurosensory deficit of the lip of 21.79 cm (95% CI 5.29 to 38.29). The overall quality of the evidence for this outcome was very low; the outcome data were fully reported in one small study of 13 patients, with differential drop-out in the control group, and patients suffered only partial loss of sensation. No studies reported on the effects of the intervention on the remaining primary outcomes of pain, difficulty eating or speaking or taste. No studies reported on quality of life or adverse events.
The overall quality of the evidence was very low as a result of limitations in the conduct and reporting of the studies, indirectness of the evidence and the imprecision of the results.