This is retrospective research mainly aims to determine the patterns of symptoms, clinical and radiological findings and outcomes in patients with trigeminal neuropathy following trauma or iatrogenic damage and how this translates into costs for the patient and society, work disability and medication use.

The trigeminal nerve and its branches are at risk of damage during multiple dental and maxillofacial procedures: endodontics, extractions, removal of wisdom teeth, implant placement, use of local anaesthesia, orthognatic surgery.

In the event of damage to these nerve branches, there is a high risk of developing a neuropathic pain that is considered very disabling for patients and that interferes with daily activities (eating, drinking, speaking, kissing, etc.). Moreover, there are few medicinal or surgical techniques available to eliminate neuropathy or reduce the symptoms.

Causal procedures (e.g. the removal of wisdom teeth) are among the most frequently performed surgical procedures. The number of injuries increases every year, partly due to an increase in dental procedures. The often relatively minimal intervention combined with the major impact of these injuries on the patient's quality of life sometimes leads to medico-legal actions. The limited symptom control with current therapies of these post-traumatic neuropathies of the trigeminal nerve causes frustration and impotence in both the patient and the attending physician, which can also lead to medical shopping.

Based on chart analysis, this study will examine the causes, possible risk factors and presenting symptoms, how this is reflected in clinical research and examinations, and which treatments are being instituted. Patient records from the Oral and Maxillofacial Surgery department between January 2010 and October 2018 will be checked. In addition, we wish to check the costs incurred by these patients as well as the work disability. To this end, a collaboration is being organised with Christian Mutuality (CM), the largest health insurance provider in Belgium.

In order to increase the power of the study, the clinical data from the already coded, retrospective dataset of Prof. Tara Renton, co-investigator, will be transferred to the dataset of this new study.

Inclusion Criteria:

• Presentation with post traumatic, iatrogenic, injury of the trigeminal nerve or its branches (eg. inferior alveolar nerve, lingual nerve)
• Iatrogenic nerve injury caused by M3 removal, implant placement, orthognathic surgery, endodontic therapy, non-M3 removal, local anesthesia injection, trauma.
• Clinical diagnosis of neurosensory deficit in the distribution of the trigeminal nerve caused by a previous dental or maxillofacial procedure in the vicinity of the affected branch.

Exclusion Criteria:

• Neuropathic pain in another region than the trigeminal nerve
• Neuropathic pain not caused by iatrogenic injury

Patients with post- traumatic, including iatrogenic, injury to branches of the trigeminal nerve seen at the department of Oral & Maxillofacial Surgery at UZ Leuven between January 2010 and October 2018 and possible subsequent post-traumatic neuropathy (PTN). To improve statistical power, the coded dataset from a retrospective study by prof. Tara Renton, co-investigator, will be provided to the principal investigator of the current study (dr. Fréderic Van der Cruyssen) and merged with the dataset acquired in this study to further analyze presentation, symptoms, clinical exam, radiographic evaluation, treatments and outcome parameters. The dataset provided by prof. Tara Renton was build by using the same inclusion and exclusion criteria between January 2010 and October 2018. This should allow for a justified merging of both datasets. Statistical analysis will determine correlation of data.

Source data will be directly accessible to the rightful instance or person on request. All medical data, the data collected in the course of the study is treated with the utmost confidentiality. The medical secrecy, the international guidelines (ICH-GCP) and the Belgian legislation are complied with. The investigators undertake to respect the conditions in the European General Data Protection Regulation (Europese Algemene Verordening Gegevensbescherming, AVG) and the Belgian legislation on the protection of natural persons with regard to the processing of personal data.

The CastorEDC (www.castoredc.com) platform will be used to ensure a systematic approach towards entering datapoints after accessing the patient record. After reading the patient record in KWS, all data will be coded immediately in the CastorEDC database by creating a new and unique identifier, the study ID.