Neuro - Focal Weakness

Question 1

What is Bell’s Palsy?

Answer 1

Bell’s Palsy:

Is an acute, unilateral, idiopathic, facial nerve (CN VII) paralysis i.e. affecting the LMNs (thus no forehead sparing)

• Cause = unknown
• More common in pregnant women

Facial nerve (CN VII) supplies - ‘face, ear, taste, tear’:

• face: muscles of facial expression
• ear: nerve to stapedius
• taste: supplies anterior two-thirds of tongue
• tear: parasympathetic fibres to lacrimal glands, also salivary glands

Question 2

What are the features of Bell’s palsy?

Answer 2

Features of Bell’s palsy:

• LMN facial nerve (CN VII) palsy - with forehead affected
• Onset = hours/days (sudden onset is more likely stroke)

Pts may have:

• post-auricular pain (can precede paralysis)
• altered taste
• dry eyes
• hyperacusis (↑ sensitivity to sound)

Question 3

How is Bell’s palsy managed?

Answer 3

Prednisolone 1 mg/kg for 10 days, within 72hrs of onset (NIH randomised control trial recommended)

(Adding aciclovir has no added benefit)

Eye care - artificial tears / eye lubricant

Question 4

Pt with Bell’s palsy wants to know the following - answer their questions:

• Will my face recover? - if so how long will it take?
• Is there any treatment?
• What caused it and will it happen again?

Answer 4

1. Facial weakness can worsen over first few days –> majority recover completely in 4-6 months (duration depends on initial severity)
   - ~30% have some degree of permanent impaired facial nerve function
   - If no improve in tone / movement in 6 months consider another diagnosis
2. Prednisolone + eye care to help manage the condition
3. Cause is unknown, some research suggests virus’ can cause it but it’s not proven

Question 5

What is Ramsay Hunt syndrome?

Answer 5

Ramsay Hunt syndrome = reactivation of the varicella zoster virus (herpes zoster) in the geniculate ganglion of the facial nerve (CN VII)

Ramsay Hunt syndrome is also called herpes zoster oticus

Features:

• Facial nerve palsy
• Ear pain
• vesicular rash around ear (occasionally on the palate / tongue)
• taste loss of anterior 2/3rds of tongue
• dry eyes + mouth
• vertigo
• tinnitus

Question 6

What are the possible causes of ‘Foot-drop’?

Answer 6

Each presents with a different picture. From distal to proximal:

Neuromuscular disease - rare + other symptoms
- e.g. Charcot-Marie-Tooth, myopathy, muscular dystrophy

deep or superficial peroneal nerve lesion

• Deep = weak dorsiflexion (tibialis anterior), weak toe extension (EDL + EHL), weak eversion (peroneal muscles), sensory loss 1st webspace
• Superficial = weak eversion, sensory loss of antero-lateral lower leg + dorsum of foot (except 1st webspace)

common peroneal nerve lesion
- e.g. knee dislocation, or extended periods of knee flexion (kneeling)

sciatic nerve lesion

• e.g. hip dislocation / #
• Differentiating features: pain in back of thigh + calf

L5 radiculopathy

• e.g. L4-L5 disc herniation affecting the L5 nerve root
• Differentiating features: weak hip abduction, back pain, sensory loss of thigh + lower leg, loss of ankle reflex

Cauda equina - rare + other symptoms

UMN pathology - rare + other symptoms
- e.g. stroke, TIA, tumour

Question 7

What is the most common cause of ‘Foot-drop’?

Answer 7

Common peroneal nerve lesion

Cause:
- Commonest = secondary to compression at neck/head of fibula .e.g.
       - sitting cross-legged, 
       - squatting, kneeling
recent weight loss
        - Baker's cyst
        - plaster casts
- Trauma e.g. fibula head #
- Diabetes
- Vitamin B12 deficiency
- Alcohol misuse

Question 8

What are the features of common peroneal nerve lesion?

Answer 8

FEATURES:

Foot-drop - described as foot ‘slapping’ on ground when walking and tripping over affected foot

Weakness of:

• dorsiflexion (tibialis anterior)
• eversion (peroneal muscles) - normal inversion as tibialis posterior innervated by tibial nerve
• big toe extension

Sensory loss - over dorsum of foot + lateral calf

Wasting of anterior tibial + peroneal muscles

Normal reflexes

Question 9

How is common peroneal neuropathy managed?

Answer 9

Conservative

• Avoid: leg crossing, squatting and kneeling
• Symptoms improve over 2-3 months

Question 10

What are the features and common cause of radial nerve palsy?

Answer 10

FEATURES:

• Wrist drop
• Sensory disturbance to dorsum of hand between 1st - 2nd metacarpals

CAUSE:

• Commonly compression of radial nerve against mid-shaft of humerus e.g. sleeping in hard chair with arm draped over the back, classically after alcohol or from partner sleeping on your arm overnight
• Distal humerus #