FP 4: Trigeminal Neuralgia Flashcards
What is Neuralgia?
- intense stabbing pain
- pain is brief but may be severe
- pain extends along course of affected nerve
- usually caused by irritation/ damage to nerve
What nerves are involved?
- trigeminal
- glossopharyngeal and vagus
- nervus intermedius
- occipital
Epidemiology of TN
- 4.3: 100000 population in usa
- more F > M
- usually elderly patients
- 60 yrs and above
Causes of Trigeminal neuralgia
- idiopathic
- classical: vascular compression of trigeminal nerve
- secondary: multiple sclerosis, space-occupying lesions, skull base bone deformity, CT disease, arteriovenous malformation
Presentation of TN
- unilateral maxillary/ mandibular division pain > ophthalmic division
- stabbing pain
- 5-10s duration
- Triggers: cutaneous, wind, cold, touch, chewing
- purely paroxymal/ with concomitant continuous pain
- remissions and relapse
TN on continuum with other cranial nerve pain disorders
- acute spasms of sharp shooting pain
- may be more than on division
- bilateral
- burning component
- vasomotor component
How does a typical pt with TN present
- older pt, >60
- mask like face
- having excruciating pain
- no obvious precipitating pathology
TN Red Flags
- younger patient >40
- sensory deficit in facial region
- hearing loss acoustic neuroma
- other cranial nerve lesions
- always test for cranial nerves to identify sensory deficit
- all patients now get MRI
Medications for TN
First line
- Carbamazepine: modified release
- Oxcarbamazepine
- Lamotrigine (Slow onset)
Second line
- Gabapentin
- Pregabalin
- Phenytoin
- Baclofen
Management of TN
- should be responsive to Carbamazepine if tolerated
- maximise efficacy and minimise side effects
- often difficult to control pain first thing in the morning
- pain diary to identify modifications neccessary to therapy
- responsive to LA
Side Effects of Carbamazepine
Blood dyscrasias
- Thrombocytopenia
- Neutropenia
- Pancytopenia
Electrolyte imbalance
- Hyponatraemia (a lower than normal level of sodium in the bloodstream)
Neurological deficits
- Paraesthesia
- vestibular problems
Liver toxicity
Skin reactions
Should you prescribe Carbamazepine in GDP?
- BNF dental preparations
- SDCEP guidelines
- Expertise
- have facilities to monitor toxicity
Surgery indications for TN
- usually not recommended if patient managing on medical therapy with moderate drug dose and no significant side effects
- only consider when approaching maximum tolerable medical management
- consider when young patients with significant drug use
Surgical options for TN
- Microvascular decompression (MVD)
- preferred surgical treatment
- requires a vessel impinging on TN root
- 12 months; 1% mortality, 10% morbidity - Destructive Central procedures
- radiofrequency thermocoagulation
- retrogasserian glycerol injection
- balloon compression
- 9 months; 2% mortality - Sterotactic radiosurgery
- gamma knife
- targeted radiation at trigeminal ganglion to kill trigeminal nerve cells - Destructive Peripheral Neurectomies
- only performed as a last resort after trial local anesthesia
- 6 months pain free without medication
- can result in allodynia as well as TN - Glycerol injection
- Balloon compression
Complications after surgery
- local effects: peripheral treatments (cryotherapy)
- sensory loss: corneal reflex, general sensation, hearing loss
- motor deficit
- may be reversible/ irreversible
Trigeminal Autonomic cephalalgias
Cluster headache vs Paroxysmal vs SUNCT
Extra about cluster headaches (the bout)
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