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. affectin 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 preceed 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:

1. Will my face recover? - if so how long will it take?
2. Is there any treatment?
3. 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 hernation 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?

What is involved in management?

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 drapped over the back, classically after alcohol or from partner sleeping on your arm overnight
• Distal humerus #