MOCK OSCE Question 1 [[L34 Neuropathic Orofacial Pain including Burning MouthSyndrome#post-traumatic-trigeminal-neuropathic-pain|Post-Traumatic Trigeminal Neuropathic Pain]] Sophie is a 22-year-old female university student who presents to your dental practice reporting persistent pain and altered sensation involving her lower left lip and chin. The symptoms began following surgical extraction of tooth 37 six months ago. She describes the pain as a constant dull ache with occasional sharp, electric-shock-like sensations. She reports that her lower lip feels “numb but painful at the same time” and states that the discomfort is affecting her ability to concentrate on her studies and is interfering with eating and socialising.
- List 3 possible causes of post-traumatic trigeminal neuropathic pain (PTTNP). (3 marks)
- Describe 3 clinical features that would support a diagnosis of PTTNP in this patient. (3 marks)
- Outline 3 key components of your initial clinical assessment of this patient. (3 marks)
- List 3 special investigations that may assist in the evaluation of this patient. (3 marks)
- List 3 pharmacological agents that may be used in the management of neuropathic pain in this patient. (3 marks)
- List 3 non-pharmacological strategies that may assist this patient in managing her condition. (3 marks)
- Identify 3 factors that may influence the prognosis and likelihood of nerve recovery in this patient. (3 marks)
First try answers
- 3 possible causes of PTTNP
- Lingual nerve damage during extraction - and resulting sensitization
- IAN nerve damage during extraction - and resulting sensitization
- Central sensitatization?
- Pain follows branches of trigeminal nerve (i.e. q tip running along )?
- Pain remains for 3 months post trauma?
- ?
- History
- palpation of muscles to rule out myalgia
- swabbing p/ts face with q tips to trace path of trigem
- Following the IASP/ DCD-TMD criteria questionnaire?
- Carbamazepine
- Pregabalin
- Gabapentin
- Gamma knife
- Acupuncture
- Risk factor reduction (stress or emotional state)
- Extent of paresthesia
- Severity of parasthesia
- ? Contents
Marking key Causes of nerve injury during extraction (any 3):
- direct surgical trauma to the inferior alveolar nerve or lingual nerve during extraction
- compression or traction of the nerve by instruments, elevators, or retractors;
- thermal injury from surgical drilling without irrigation
- stretching injury during forceful elevation or sectioning of the tooth
- Post-operative hematoma causing secondary nerve compression
- chemical injury from local anesthetic agents injected intra-neurally
- anatomical proximity of the tooth roots to the inferior alveolar canal (predisposing risk factor )
Clinical features supporting PTTNP (any 3)
- Persistent pain lasting beyond the expected healing period (typically defined as more than 3 months post-procedure );
- pain with a neuropathic character:burning,aching, shooting, or electric-shock-like sensations;
- Sensory disturbance within the ian distribution; hypoaesthesia (reduced sensation), paraesthesia (abnormal sensation such as tingling or “pins and needles”), or dysasethesia (unpleasant or painful abnormal sensation):
- Allodynia (pain evoked by a normally non-painful stimulus) or hyperalgesia (exaggerated pain response to a painful stimulus)
- Absence of identifiable local dental pathology (e.g. infection, retained root fragment to account for the pain)
- Pain confined to the anatomical distribution of the affected nerve (lower lip, chin , mandibular teeth, adjacent gingiva).
Key components of the initial clincial assessment (any 3)
- Detailed pain history: onset and timeline in relation to the procedure, pain character and quality, severity using a numerical rating scale (NRS 0-10), distribution, and aggravating/relieving factors;
- comprehensive intraoral examination: assessment of the extraction socket for sings of infection, dry socket, or healing complications, and examination of adjacent teeth and soft tissues
- Cranial nerve sensory examination: bedside assessment of hte inferior alveolar and lingaul nerve distributions using light touch, pin-prick and two-point discrimination
- Medical and medicaiton history including current use of analgesics or other medications
- Psychosocial assessment: impact on daily activities, sleep quality, study, social function and emotional wellbeing
- assessment of any prior investigations or treatments performed since the proceder
**Special investigations **:
- Panoramic radiograph (OPG): to assess the healing extraction socket, exclude retained fragments or bony pathology, and review the relationship of the inferior alveolar canal to the former tooth position;
- CBCT imaging: where greater anatomical detail of the inferior alveolar canal and surrounding structures is required
- Cranial nerve examination; quantitative or qualitative sensory testing (QST): structured psychophysical testing to objectively characterize the sensory deficit and identify allodynia or hyperalgesia;
- Standardizes sensory mapping: documentation of the area of sensory disturbance using a dermatomal map with photographic record
Pharmacological Management
- Tricyclic antidepressants : e.g. amitriptyline or nortriptyline - first-line agents for peripheral neuropathic pain, acting via noradrenergic and serotonergic pathways;
- Gabapentinoids e.g. gabapentin or pregabalin - act on voltage-gated calcium channels to reduce central sensitization and abnormal neuronal firing
- Anticonvulsants: e.g. carbamazepine or oxcarbazepine - sodium channel blockers with established efficacy in trigeminal neuropathic conditions
- Serotonin-noradrenaline reuptake inhibitors (SNRIs) e.g. duloxetine or venlafaxine - an alternative first-line option with evidence in neuropathic pain conditions
- Topical agents (e.g topical lidocaine (5% patch or gel) or topical capsaicin) - useful adjuncts with a localized mechanism of action and minimal systemic side effects
Non - Pharmacological Management
- Patient education and reassurance: explaining the nature of neuropathic pain, the expected clinical course, and the rationale for treatment
- Cognitive-behavioural therapy (CBT): to address maladaptive pain beliefs, catastrophising and fear-avoidance behaviours
- Pain neuroscience education: structured educaiton to improve understanding of central sensitisaiton and neural plasticity
- Physiotherapy or orofacial physiotherapy: manual techniques and sensory re-education to promote neural recovery and functional rehabilitation
- Transcutaneous electrical nerve stimulation (TENS): neuromodulatory technique providing symptomatic pain relief:
- Mindfulness-based stress reduction (MBSR): evidence-based approach to improving pain coping and psychological well being:
Prognostic factors influencing nerve recovery (any 3):
- Time elapsed since injury: earlier intervention and spontaneous recovery are more likely wihtin the first 3-6 months; delayed recovery beyond 12 months is associated with poorer outcomes
- Severity of the nerve injury: neuropraxia (conduction block without axonal disruption) carries the best prognosis for full recovery; axonotmesis and neurotmesis carry progressively worse prognoses
- Age of the patient: younger patients generally dmeonstrate superior nerve regeneration capcity compared with older individuals
- Development of central sensitisation: establishment of central sensitsaiton is associated with a more refractory clinical course and guarded prognosis
- Psychological factors: high levels of pain catastrophising, anxiety, or depression are associated with worse outcomes and greater disability
- Anatomical factors: documented close proximity of the tooth roots to the inferior alveolar canal on pre-operative imaging, suggesing a higher-risk extraction, may indicate more significant initial nerve injury
Total: 21 marks