Guillain-Barré + Bell’s palsy + Essential tremor Flashcards
What is Guillain-Barré syndrome?
Guillain-Barré syndrome (GBS) is an autoimmune, rapidly progressive demyelinating condition of the peripheral nervous system, often triggered by infection.
Typical presentation of Guillain-Barré syndrome
Symmetrical muscle weakness usually affecting the lower extremities before the upper extremities (ascending weakness), with a history of infection in the preceding 6 weeks.
The progression is subacute with peak symptoms occurring within 2-3 weeks of disease onset.
Symptoms of Guillain-Barré syndrome
- Tingling and numbness in hands and feet often precedes muscle weakness
- Symetrical, progressive, ascending weakness
- Unsteady when walking
- Back and leg pain
- Shortness of breath
- Facial weakness and speech problems
Signs of Guillain-Barré syndrome
- Reduced sensation in affected limbs: sensory findings are usually mild
- Symmetrical weakness in lower extremities first, progressing to the upper limbs: proximal muscles are affected earlier than distal muscles
- Ataxia with hyporeflexia (or areflexia) in affected limbs
- Autonomic dysfunction eg tachycardia, hypertension, postural hypotension, urinary retention
- Respiratory distress: shortness of breath, respiratory muscle weakness requiring mechanical ventiallation in severe cases
- Cranial nerve involvement and bulbar dysfunction eg diplopia or facial droop
Although GBS is predominantly a clinical diagnosis evidenced by progressive weakness and areflexia in the weaker limbs, investigations are mainly performed to exclude other causes.
What are the primary investigations?
- Bloods
- U&Es: electrolyte abnormalities resulting in neuropathic symptoms
- B12 and folate: deficiency associated with neurological features
- TFTs: to exclude hypothyroidism as a cause of weakness
- LFTs: elevation of hepatic enzymes is associated with more severe disease
- Anti-ganglioside antibodies: can be used to differentiate GBS variants
- Cultures: stool or sputum if there are ongoing infective features, eg gastroenteritis
- Lumbar puncture: raised protein with normal WBC count is typical, although an initial normal protein level does not exclude GBS
- Spirometry: to monitor respiratory function as 20% of patients require mechanical ventilation at some stage
Investigations to consider for GBS
- Nerve conduction studies: not required for diagnosis; findings will typically be suggestive of demyelination eg reduced conduction velocity
- MRI brain and spinal cord: to differentiate between GBS and other possible neurological causes eg transverse myelitis
First line management of GBS
- IV immunoglobulins (IVIg): 5 day treatment course commenced within the first 2 weeks of symptom onset OR
- Plasma exchange: 5 treatments of 2-3L over 2 weeks commenced within the first 4 weeks of symptom onset
Complications of GBS
- Type 2 respiratory failure: may require mechanical ventilation in intensive care
- Impaired mobility: may persist for months to years after the initial onset of GBS
- Pulmonary complications: including infections due to intubation, or pulmonary emboli due to immobility and pro-inflammatory state
- Autonomic dysfunction: ileus and urinary retention may occur, as may arrhythmias
- Psychiatric impact: depression, post-traumatic stress disorder and anxiety are all associated with GBS
Where does the facial nerve exit the brainstem and which structures does it pass through on its way to the face?
The facial nerve exits the brainsten at the cerebellopontine angle. On its journey to the face it passes through the temporal bone and parotid gland.
The facial nerve divides into five branches that supply different areas of the face. Name them.
- Temporal
- Zygomatic
- Buccal
- Marginal mandibular
- Cervical
Function of the facial nerve
There are three functions of the facial nerve: motor, sensory and parasympathetic.
Motor: Supplies the muscles of facial expression, the stapeidus in the inner ear and the posterior digastric, stylohyoid and platysma muscles in the neck
Sensory: carries taste from the anterior 2/3 of the tongue
Parasympathetic: it provides the parasympathetic supply to the submandibular and sublingual salivary glands and the lacrimal gland
Why is it important to disstinguish between and upper motor neurone and lower motor neurone facial nerve palsy.
A patient with a new onset upper motor neurone facial nerve palsy should be referred urgently with a suspected stroke, whereas patients with lower motor neurone facial nerve palsy can be reassured and managed in the community.
How would you differentiate between an upper motor neurone and lower motor neurone facial nerve palsy?
In an upper motor neurone lesion, the forehead will be spared and the patient can move their forehead on the affected side.
In a lower motor neurone lesion, the forehead will not be spared and the patient cannot move their forehead on the affected side.
Causes of upper motor neurone facial nerve palsy
Unilateral upper motor neurone lesions:
- Cerebrovascular accidents (strokes)
- Tumours
Bilatera upper motor neurone lesions:
- Pseudobulbar palsies
- Motor neurone disease
What is Bell’s palsy?
It is a relatively common, idiopathic condition. It presents as a unilateral lower motor neurone facial nerve palsy.
The majority of patients fully recover over several weeks but recovery may take up to 12 months. A third are left with some residual weakness.
