Disorder of sensation: trigeminal neuralgia, shingles, cauda equina, carpel tunnel syndrome

Question 1

Define/causes of trigeminal neuralgia?

Answer 1

Aka tic douloureux.

A chronic facial pain condition that affects the distribution of the trigeminal nerve, which has three branches:
- ophthalmic (V1)
- maxillary (V2)
- mandibular (V3)

Can be primary (idiopathic) or secondary.
Could be due to:
- malignancy (nerve compression)
- multiple sclerosis
- sarcoidosis
- lyme disease
- arteriovenous malformation (tangled blood vessels)

Question 2

Presentation of trigeminal neuralgia?

Answer 2

Unilateral facial pain.

Sudden, severe, and brief stabbing or shooting pain.

Triggered by lightly touching/eating/wind blowing on the affected side of face

Question 3

Diagnosis/IVx of trigeminal neuralgia?

Answer 3

Clinical diagnosis

MRI (to exclude tumours or vascular compression)

Question 4

Management of trigeminal neuralgia?

Answer 4

Medical:
- Carbamazepine (1ST LINE)
- Phenytoin
- Lamotrigine
- Gabapentin

Surgical:
- microvascular decompression
- tx underlying cause (e.g. removing tumour)
- alcohol or glycerol injections

Question 5

Define/causes of shingles?

Answer 5

A reactivation of the varicella zoster virus which can lie dormant in nerve ganglia following primary infection (chickenpox).

Question 6

Presentation of shingles?

Answer 6

Tingling feeling
Erythematous papules occurring along one or more dermatomes (never crosses the midline).
Erythematous papules can turn into fluid filled vesicles.
Fever
Headache
Malaise

Question 7

Diagnosis/IVx of shingles?

Answer 7

Clinical diagnosis

Question 8

Management of shingles?

Answer 8

Oral antiviral within 72h of onset (aciclovir)

Admit to hospital if severe disease or immunocompromised (require IV abx)

Avoid contact with pregnant women, babies, immunocompromised people until lesions are fully crusted over.

Analgesia for pain relief (ibuprofen, if it doesn’t work, offer amitriptyline (off-label use), duloxetine (off-label use), gabapentin, or pregabalin)

One-off vaccine available for shingles (Advised for pts in 70s)

Question 9

Define/causes of cauda equina?

Answer 9

Compression of the cauda equina (bundle of nerve roots that extend from the termination of the spinal cord at L1 level; aka horse tail).

Causes:
- lumbar disc herniation
- neoplasms
- abscess
- iatrogenic

Question 10

Presentation of cauda equina?

Answer 10

Saddle anaesthesia (can’t feel toilet paper)
Lower back pain
Bladder and bowel disturbances (constipation/retention or incontinence)

Question 11

Diagnosis/IVx of cauda equina?

Answer 11

whole spine MRI

Question 12

Management of cauda equina?

Answer 12

Surgical decompression within 48hours

If malignancy identified on MRI or suspicion is high,
- OFFER dexamethasone 16 mg with PPI

Question 13

Define/causes of carpal tunnel syndrome?

Answer 13

Median nerve compression as it traverses the narrow carpal tunnel from the forearm to the hand.

Cause:
- repetitive wrist activities
- systemic diseases (like diabetes or rheumatoid arthritis)
- pregnancy
- anatomical variations

Question 14

Presentation of carpal tunnel syndrome?

Answer 14

Pain + paraesthesia to the lateral 3.5 digits (due to the impingement of the palmar digital branch of the median nerve)

Wasting of thenar eminence

Symptoms worse at night or after activities involving wrist flexion.

Question 15

Diagnosis/IVx of carpal tunnel syndrome?

Answer 15

Clinical diagnosis

EMG (Electromyography)
- ASSESSES electrical activity of the muscles at rest and during contraction.

NCS (Nerve Conduction Studies)
- MEASURES speed and strength of signals traveling through the median nerve.

MRI/X-RAY (rule out structural abnormalities)

Question 16

Management of carpal tunnel syndrome?

Answer 16

Conservative:
- wrist splinting
- NSAIDs
- corticosteroid injections
- modifying activities that exacerbate symptoms

Surgery:
- if unresponsive to tx
- Surgical release of the transverse carpal ligament is the most common procedure.
- physical therapy post-surgery