Neuroscience Flashcards
Learning objectives
Answer
Define Bell’s palsy
• Idiopathic lower motor neurone facial nerve palsy
Explain the aetiology/risk factors of Bell’s palsy
- IDIOPATHIC
- 60% are preceded by an upper respiratory tract infection
- This suggests that it has a viral or post-viral aetiology
Summarise the epidemiology of Bell’s palsy
• Most cases: 20-50 yrs
Recognise the presenting symptoms of Bell’s palsy
• Prodrome of pre-auricular pain (in some cases)
• This is followed by unilateral facial weakness and droop
• Maximum severity: 1-2 days
• 50% experience facial, neck or ear pain or numbness
• Hyperacuisis
o This is due to stapedius paralysis
• Loss of taste (uncommon)
• Tearing or drying of exposed eye
o Because it may be difficult to close the eye fully
Recognise the signs of Bell’s palsy on physical examination
• Lower motor neurone weakness of facial muscles
o Affects ipsilateral muscles of facial expression
o Does NOT spare the muscles of the upper part of the face (unlike upper motor neurone facial nerve palsy)
• Bell’s Phenomenon
o Eyeball rolls up but the eye remains open when trying to close their eyes
• Despite reporting unilateral facial numbness, clinical testing of sensation is normal
• Examine the ears to check for other causes of facial nerve palsy (e.g. otitis media, herpes zoster infection)
Identify appropriate investigations for Bell’s palsy
- Usually unnecessary (except for excluding other causes)
* EMG - may show local axonal conduction block
Generate a management plan for Bell’s palsy
• Protection of cornea with protective glasses/patches or artificial tears
• High-dose corticosteroids is useful within 72 hrs
o Only given if Ramsey-Hunt Syndrome is excluded
• Surgery - lateral tarsorrhaphy (suturing the lateral parts of the eyelids together)
o Performed if imminent or established corneal damage
Identify possible complications of Bell’s palsy
• Corneal ulcers
• Eye infection
• Aberrant reinnervation
o E.g. Blinking may cause contraction of the angle of the mouth due to aberrant sympathetic innervation of orbicularis oculi and oris
o Crocodile Tears Syndrome - parasympathetic fibres may aberrantly reinnervate the lacrimal glands causing tearing whilst salivating
Summarise the prognosis for patients with Bell’s palsy
• 85-90% recover function within 2-12 weeks with or without treatment
Define central nervous system (CNS) tumours
- Tumours of the central nervous system.
- NOTE: brain tumours cannot be truly differentiated into benign and malignant because supposedly ‘benign’ tumours can cause significant morbidity and mortality
Instead they are differentiated into:
High-Grade = a tumour that grows rapidly and aggressively
• Glioma and glioblastoma multiforme
• Primary cerebral lymphoma
• Medulloblastoma
Low-Grade = a tumour that grows slowly and may or may not be successfully treated • Meningioma • Acoustic neuroma • Neurofibroma • Pituitary tumour • Craniopharyngeoma • Pineal tumour
Brain metastases commonly arise from: • Lung • Breast • Stomach • Prostate • Thyroid • Colorectal
Explain the aetiology / risk factors of central nervous system (CNS) tumours
• Can arise from any of the cells in the CNS (e.g. glial cells, ependymal cells, oligodendrocytes)
• Risk Factors
o Ionising radiation
o Immunosuppression (e.g. HIV)
o Inherited syndromes (e.g. neurofibromatosis, tuberous sclerosis)
Summarise the epidemiology of central nervous system (CNS) tumours
- Primary brain tumours = 2% of tumours diagnosed in the UK
- AIDS patients have an increased risk of developing CNS tumours
- Can develop at any age but are more common between 50-70 yrs
Recognise the presenting symptoms & signs of central nervous system (CNS) tumours
- Presentation depends on the size and location of the tumour
- Headache (worse in the morning and when lying down)
- Nausea and vomiting
- Seizures
- Progressive focal neurological deficits
- Cognitive and behavioural symptoms
- Papilloedema
Identify appropriate investigations for central nervous system (CNS) tumours and interpret the results
- Bloods - check CRP/ESR to eliminate other causes (e.g. temporal arteritis)
- CT/MRI
- Biopsy and tumour removal
- Magnetic resonance angiography - define changing size and blood supply of the tumour
- PET
- NOTE: distant metastases are RARE with primary CNS tumours
Define cluster headache
• A neurological disorder characterised by recurrent, severe headaches on one side of the head typically around the eye, tending to recur over a period of several weeks.
Explain the aetiology/risk factors of cluster headaches
- UNKNOWN aetiology
* Genetic factor implicated
Summarise the epidemiology of cluster headaches
- More common in MEN
* Usually occurs between 20-40 yrs
Recognise the presenting symptoms and signs of cluster headaches
• TWO types of cluster headaches:
o Episodic - occurring in periods lasting 7 days - 1 year, separated by pain-free periods lasting a month or longer. Cluster periods usually last between 2 weeks - 3 months
o Chronic - occurring for 1 year without remissions or with short-lived remissions of less than a month. Chronic cluster headaches can arise de novo or arise from episodic cluster headaches.
• Pattern of Occurrence
o Headaches occur in bouts lasting 6-12 weeks
o These occur once every year or once every 2 years, and tends to occur at the same time each year
o Headaches typically occurs at night, 1-2 hours after falling asleep
o The interval between bouts tends to be the same
o 10% with episodic cluster headaches go on to develop chronic cluster headaches
• Nature of Symptoms
o Pain comes on rapidly over around 10 mins
o Pain is intense, sharp and penetrating
o Pain is centred around the eye, temple or forehead
o Pain is unilateral
o Pain typically lasts around 45-90 mins (range: 15 mins - 3 hours)
o Pain occurs once or twice daily
o Associated autonomic features:
• Ipsilateral lacrimation
• Rhinorrhoea
• Nasal congestion
• Eye lid swelling
• Facial swelling
• Flushing
• Conjunctival injection
• Partial Horner’s syndrome
o Patients find it difficult to stay still and will pace around, occasionally banging their heads on things
• Triggers
o ALCOHOL - major precipitant
o Exercise and solvents
o Sleep disruption
Identify appropriate investigations for cluster headaches
- CLINICAL diagnosis based on history
* Neurological examination may be useful
Define encephalitis
• Inflammation of the brain parenchyma
Explain the aetiology / risk factors of encephalitis
Most commonly due to VIRAL INFECTION Viral Causes o Herpes Simplex Virus - MOST COMMON in the UK o VZV o Mumps o Adenovirus o Coxsackie o EBV o HIV o Japanese encephalitis Non-Viral (RARE) o Syphilis o Staphylococcus aureus In immunocompromised patients o CMV o Toxoplasmosis o Listeria Autoimmune or Paraneoplastic o Associated with certain antibodies (e.g. anti-NMDA, anti-VGKC)
Summarise the epidemiology of encephalitis
• UK incidence: 7.4/100,000
Recognise the presenting symptoms of encephalitis
- In most cases, encephalitis is self-limiting and mild
- Subacute onset (hours to days)
- Headache
- Fever
- Vomiting
- Neck stiffness
- Photophobia
- Behavioural changes
- Drowsiness
- Confusion
- History of seizures
- Focal neurological symptoms (e.g. dysphagia, hemiplegia)
- Obtain a detailed TRAVEL HISTORY