Flashcards in Nervous System Deck (203)
What is Bell's palsy?
Idiopathic lower motor neurone facial (VII) nerve palsy
What is the aetiology of Bell's palsy?
- 60% are preceded by an upper respiratory tract infection, suggesting a viral or post-viral aetiology
What is the epidemiology of Bell's palsy?
- Annual incidence is 14-40 in 100,000
- Most cases: 20-5o year
What are the presenting symptoms of Bell's palsy?
- Prodrome of pre-auricular pain in some cases followed by acute (hours/days) onset unilateral facial weakness and droop. Maximum severity within 1-2 days
- 50% experience facial, neck or ear pain or numbness
- Hypersensitivity to sound (hyperacusis caused by stapedius paralysis)
- Loss of taste sense (uncommon)
- Tearing or drying of exposed eye
What are the signs of Bell's palsy on examination?
- Lower motor neurone weakness of facial muscles (affects all of the ipsilateral muscles of facial expression and does not spare the muscles of the upper part of the fact as seen in UMN facial nerve palsy)
- Bell's phenomenon: Eyeball rolls up but eye remains open when trying to close the eyes. Although patient may report unilateral facial numbness, clinical testing of sensation is normal. The ear should be examined to exclude other causes (e.g. otitis media, herpes zoster infection)
What are the investigations for Bell's palsy?
- Usually unnecessary except to exclude other causes e.g. Lyme serology, herpes zoster serology
- EMG: May show local axonal conduction block in facial canal. Only useful more than one week after onset
How is Bell's palsy managed?
- Protection of cornea with protective glasses/patches and artificial tears
- High dose corticosteroids (prednisolone) is beneficial within 72h (given only if Ramsay Hunt's syndrome is excluded) Little evidence for aciclovir
- Surgery: Lateral tarsorrhaphy (suturing the lateral parts of the eyelids together) if imminent of established corneal damage
What are the possible complications of Bell's palsy?
- Corneal ulcers, eye infection
- Aberrant reinnervation may occur e.g. blinking may cause contraction of the angle of the mouth as a result of simultaneous innervation of obicularis oculi and ori.
- Parasympathetic fibres may also aberrantly reinnervate causing 'crocodile tears' when salivating
What is the prognosis for Bell's palsy?
Most (85-90%) recover function within 2-12 weeks with or without treatment
What is a cluster headache?
- Unilateral attacks lasting 15-180 minutes associated with autonomic symptoms secondary to parasympathetic hyperactivity and sympathetic hypo-activity
- Pain often localised to unilateral orbital, supra-orbital and/or temporal areas and can occur from once every other day to 8 times per day
- Considered one of the most painful conditions known to humanity
What is the aetiology of a cluster headache?
- History of head trauma, heavy cigarette smoking and heavy alcohol intake all associated though no causal relationship found
What is the epidemiology of cluster headaches?
- One of few primary headaches that affect men predominantly
- Age of onset: 20-40 yrs usually
What are the presenting symptoms of a cluster headache?
- Male sex
- Family history
- Head injury
- Cigarette smoking
- Heavy drinking
- Repeated attack of unilateral pain
- Excruciating pain
- Nausea, vomiting
- Migrainous aura
What are the signs of a cluster headache on examination?
- Lacrimation, rhinorrhoea and partial Horner's syndrome
- Photophobia, phonophobia
What are the investigations for a cluster headache?
- Brain CT or MRI: normal in primary cluster headache; abnormal results might indicate secondary causes (e.g. tumour, cavernous sinus pathology)
- ESR: normal in primary
- Pituitary function tests: Normal in primary, abnormalities suggest secondary causes resulting from pituitary adenoma
What is dementia?
Progressive deficits in memory and one or more domains- language, visuospatial, praxis (inability to perform actions e.g. dressing apraxia), in a setting of clear consciousness and interfering with work, social activities, relationships
- Alzheimer's, Vascular, Lewy body, Pick's disease
What is the aetiology of Alzheimer's dementia?
- Lesions in the brain- tau neurofibrillary tangles, plaques of beta amyloid and neurone loss with corticol atrophy, loss of ACh. Cerebral amyloid angiopathy. Cerebral atrophy
- Neurone loss in: hippocampus, amygdala, temporal neocortex, subcorticol nuclei
- 95% show signs of vascular dementia
What is the aetiology of dementia?
- Toxic: Alcohol, lead, barbs, drug abuse
- Metabolic: low thiamine, low T4, low B12, low folate, low glucose (repeated), pellagra (niacin or B3 deficiency)
- Head trauma: injury, subdural haemorrhage
- Tumours: frontal, posterior fossa (causing hydrocephalus), brain mets, paraneoplastic, meningioma
- Infection: WHipple's disease, HIV, syphillis, CNS cysticerosis, Cryptococcosis
- Vascular: multiple infarcts
- Inflammation: SLE, sarcoid, vasculitis, multiple sclerosis
- Inherited: Wilson's, Huntington's, cerebellar ataxias
- Degenerative: PD, CJD, Pick's, Lew body dementia
- Familial autosomal dominant Alzheimer's
- CADASIL: Cerebral Autosomal-Dominant Arteriopathy with Subcorticol Infarcts and Leykoencephalopathy
What is the epidemiology of dementia?
- Rare under 55 yrs
- Over 65s: 5-10%
- Over 80: 20%
- Over 100: 70%
What are presenting symptoms of dementia?
- Initial presentation is usually memory loss over months or years.
- If days: think infection/stroke
- If weeks: depression
- In later stages: non-cognitive symptoms: agitation, aggression, apathy
- Aggression, wandering, agitation, hallucinations, flight of ideas, logorrhoea: incoherent talkativeness
- Low repetitive speech, apathy, mood disturbance: depression is common but may also cause dementia
What are the signs of dementia on examination?
- Normal pressure hydrocephalus: dilated ventricles without dilated cerebral sulci. Gait apraxia, incontinence
- Cognitive testing: MMSE score less than 24 abnormal. Severe is less than 9 points
- Verbal recall: Hopkin's verbal learning test
- Executive function: clock drawing task
- Physical exam: cause of impairment, risk factors for vascular dementia, parkinonism
What are the investigations for dementia?
- Bedside cognitive testing: impaired recall, nominal dysphasia, disorientation, constructional dyspraxia and impaired executive function
- FBC: rule out anaemia
- Metabolic panel: exclude abnormals odium, calcium, glucose levels
- Serum TSH: TSH may be low or high
- Serum vitamin B12: may be low
- Urine drug screen: may be positive
- CT: may exclude space-occupying lesions or other pathology
- MRI: generalised atrophy with medial temporal lobe and later parietal predominance
What is encephalitis?
Inflammation of the brain parenchyma
What is the aetiology of encephalitis?
Majority of cases, it is the result of viral infection
- Virus: Most common in UK is HSV. Others include herpes zoster, mumps, adenovirus, coxsackie, echovirus, enterovirus, measles, EBV, HIV, rabies (Asia) and arboviruses transmitted by mosquitoes e.g. Japanese B encephalitis
- Non-viral: rare e.g. syphilis, S aureus
- Immunocompromised: CMV, toxoplasmosis, Listeria
- Autoimmune or paraneoplastic: May be associated with antibodies e.g. anti-NMDA or anti- VGKC
What is the epidemiology of encephalitis?
Annual UK incidence is 7.4 in 100,000
What are the presenting symptoms of encephalitis?
- In many cases, it is mild self-limiting illness
- Subacute onset (hours to days) headache, fever, vomiting, neck stiffness, photophobia i.e. symptoms of meningism (meningoencephalitis) with behavioural changes, drowsiness and confusion
- Often history of seizures
- Focal neurological symptoms e.g. dysphagia and hemiplegia may be present
- Important to obtain detailed travel history
What are the signs of encephalitis on examination?
- Decreased level of consciousness with deteriorating GCS, seizures, pyrexia
- Signs of meningism: Neck stiffness, photophobia, Kernig's test positive. Signs of raised intracranial pressure: hypertension, bradycardia, papilloedema
- Focal neurological signs
- Minimental examination may reveal cognitive or psychiatric disturbances
What are the investigations for encephalitis?
- Blood: FBC (raised lymphocytes), U&E (SIADH may occur, glucose (compare with CSF glucose) viral serology, ABG
- MRI/CT: Excludes mass lesion. HSV produces characteristic oedema of the temporal love on MRI
- Lumbar puncture: Raised lymphocytes, monocytes and protein. Glucose usually normal. CSF culture is difficult, PCR now first line
- EEG: May show epileptiform activity e.g. spiking activity in temporal lobes
- Brain biopsy: now very rarely performed
What is epilepsy?
- Epilepsy: More than 2 seizures
- Seizure (ictus): Paroxysmal synchronised corticol electrical discharges