Neurology Flashcards
Define meningitis
Infection of the meninges associated with infection
Types of meningitis
Bacterial - serious infection with 5-10% mortality
- 0-3 months = GBS, E.coli, listeria monocytogenes
- 1 month - 6 years = Neisseria meningitides, streptococcus pneumonia
- 50 + = listeria monocytogenes, strep pneumonia
Viral - more common, less severe, usually self-limiting
Risk factors for meningitis
Less than 5 or 65 + Non-immunisation Immunodeficiency Cancer - leukaemia and lymphoma Asplenia - increased risk of overwhelming infection with encapsulated bacteria - strep pneumoniae, n. meningitis Summer and autumn Exposure to mosquitos
Pathophysiology of meningitis
Pathogens reach the CNS by haematogenous spread or direct extension
Cross BBB via infection of endothelial cells or migrating leukocytes
Pathogens multiple in subarachnoid space stimulating immune response
Release of inflammatory mediators and activated leucocytes and endothelial damage causes
- cerebral oedema
- raised ICP
- decreased cerebral blood flow
Presentation of meningitis
Headache N+V Photophobia Neck stiffness - resistance to passive neck flexion Fever Altered mental state/confusion Seizures - strep pneumonia and h. influenzea Infants - hypothermia - irritability - lethargy - poor feeding - apnoea - high pitched cry Focal neurological deficit - dilated non-reactive pupil - ocular motility abnormality - abnormal visual field defects - gaze palsy - arm or leg drift - facial palsy - balance problems Rash Kerning's sign - severe stiffness of hamstring causing inability to straight leg when hip is flexed at 90 Brudzinski's sign - severe neck stiffness causes patient hip and knees to flex when the neck is flexed
Ix for meningitis
LP
CSF gram stain, culture, viral PCR and antigen detection - identify causative organism
Blood culture
FBC - leukocytosis, anaemia and thrombocytopenia
CRP - elevated
Blood gas - acidosis
Clotting profile
CT head - brain infarct, cerebral oedema, hydrocephalus in bacterial
MRI - if focal neuro signs present
Features of meningitis of LP
Bacterial - polymorphonocular pleocytosis - elevated protein - low glucose Viral - elevated WCC - normal or elevated protein - normal or low glucose
When is LP contraindicated
Cardioresp instability Focal neuro signs Signs of raised ICP Coagulopathy Thrombocytopenia
Mx of meningitis
Viral
- supportive care
- antiviral therapy - HSV, varicella zoster or CMV
Bacterial
- empirical abx until organism identified - meropenem 1g
- ceftriaxone for strep pneumoniae and h.influenzae
- gentamycin and ampicillin for GBS
- benzylpenicillin for n.menigitidis
- dexamethasone
Complications of meningitis
Hearing impairment - inflammation of cochlear hair cells Local vasculitis - cranial nerve palsies Local cerebral infarction Subdural effusion Hydrocephalus - fibrin blocks Cerebral abscess
DDx for meningitis
Encephalitis
- abnormal cerebral function with fever
- ix with CT or MRI head
Prophylaxis for meningitis
· Rifampicin/ciprofloxacin to eradicate nasopharyngeal carriage of all household contacts for meningococcal meningitis or Hib infection
· Household contacts of patient who has had men C should receive the men C vaccine
Define encephalitis
Inflammation of the brain parenchyma associated with neurological dysfunction
Epidemiology of encephalitis
Peak incidences at < 1 year and > 65 years
Risk factors for encephalitis
<1 or > 65 years Immunodeficiency Viral infection Insect bites Swimming in warm freshwater Vaccination - a/w acute disseminated encephalomyelitis
Pathophysiology of encephalitis
Most commonly caused by viruses - herpesvirus - enterovirus Pathogens reach CNS by haematogenous spread or retrograe axonal transport Colonise the brain paranchyma
Presentation of encephalitis
Insidious onset Fever Rash Altered mental state and confusion Focal neurological deficit Meningismus Signs of resp/GI infection Seizures
Ix for encephalitis
FBC - elevated WCC Peripheral blood smear LFTs - abnormal in rickettsia, CMV, EBV Blood culture Throat swab Nasopharyngeal aspirate Sputum culture LP CT head - hypodense lesion MRI head - hyperintense lesion, oedema and breakdown of BBB EEC - background slowing
Mx of encephalitis
IV acyclovir
DDx of encephalitis
Meningitis
Define idiopathic intracranial hypertension
Raised ICP with no known cause
Epidemiology of IIH
Incidence of 1/100,000
Mean age at diagnosis 30
Risk factors for IIH
Female Weight gain Sleep apnoea Nalidixic acid use Nitrofurantoin Isotretinoin Thyroid replacement therapy Previous inflammation - meningitis
Pathophysiology of IIH
Increased resistance to CSF absorption via arachnoid granulations and/or nerve root sheaths
ICP must then rise for CSF to be absorbed
Presentation of Idiopathic Intracranial Hypertension
Headache - severe, daily headaches, pulsatile
Visual field loss - usually mild
Transient visual obscuration - transient visual loss that lasts for < 30 secs
Pulse-synchronous tinnitus
Photophobia
Retrobulbar pain - pain with eye movements
Optic disc swelling
Decreased visual acuity - normally only if longstanding
Ocular motility defects
Diplopia
Relative afferent pupillary defect
IX for idiopathic intracranial hypertension
Visual field testing - enlargement of physiological blind spot and loss of inferonasal
Fundoscopy - grading of papilloedema
MRI brain - axial and sagittal views, assess for intracranial and intraorbital pathology
LP - L3/4
- opening pressure > 250mmH2O indicated raised ICP
- must exclude intracranial mass lesion by CT or MRI
Features of IIH on fundoscopy
o Stage 0 (normal optic disc) – 3-4mm to the nasal side of the fovea. Vertically oval with a central depression (optic cup). Normally orange/pink in colour
§ Retinal nerve fibre layer is prominent at nasal, superior and inferior poles in inverse proportion to disc diameter
§ Radial nerve fibre layer striations may be seen, without tortuosity
o Stage 1 (very early papilloedema)
§ Disruption of the normal radial nerve fibre layer with grey opacity accentuating nerve fibre layer bundles
§ Subtle grey halo with temporal gap. Obscures underlying retinal details but leaves temporal disc margin normal
o Stage 2 (early papilloedema)
§ Complete peripapillary halo
§ Elevation of the nasal border
§ No major vessel obscuration
o Stage 3 (moderate papilloedema)
§ Obscuration of one or more segments of major blood vessels leaving the disc
§ Complete peripapillary halo, which has an irregular outer fringe
§ Elevation of all borders
o Stage 4 (marked papilloedema)
§ Total obscuration of a segment of a major blood vessel on the disc
§ Elevation of whole nerve head, including the cup
§ Complete border obscuration
§ Complete peripapillary halo
o Stage 5 (severe papilloedema)
§ Obscuration of all vessels, both on the disc and leaving the disc
Mx of IIH
Conservative
- weigh reduction
- elimination of possible causal factors - medications, low sodium diet, advise mild fluid restriction
- optical prism glasses - diplopia
Medical
- Acetazolamide - reduce intra-ocular pressure, avoid 1st trimester
- Furosemide - reduce BP
- Topiramate
- Amitriptyline - 1st line analgesia
Surgical
- CSF shunting - relieves headache in 50% and may help recover vision and reduce papilloedema
- optic nerve sheath fenestration - may help recover vision and reduce papilloedema
Complications of IIH
Irreversible visual loss
Brain herniation
- preceded by Cushing reflex - hypertension, irregular breathing and bradycardia
Define epilepsy
Recurrent seizure disorder secondary to increased neuronal excitability
Types of epilepsy
Generalised - discharge in both hemispheres
- absence - interruption in activity often with blank stare of inaction
- Typical
- Atypical
- Myoclonic absence
- Eyelid myoclonia
- motor
- clonic - rhythmic muscular jerking
- tonic - extension or flexion of extremities
- tonic-clonic - tonic then clonic
- myoclonic - brief arrhythmic muscular jerking
- atonic - brief loss of muscle tone - drop attack
Focal - seizures arise from one part of hemisphere
- frontal - clonic movements or tonic with upper arms raised
- temporal - lip smacking
- occipital - stereotyped visual hallucinations
- parietal - contralateral dysaesthesias
Risk factors for epilepsy
Fhx Metabolic/neurodegenerative disorders Head trauma Autism - focal Hx of febrile seizures
Presentation of epilepsy
Depends on type
Incontinence
Tongue biting
Post-ictal phenomena - sleepiness, headaches, amnesia, confusion
Ix for epilepsy
EEG - seizures provoked if not video EEG or 24 hr EEG
Blood glucose, FBC, metabolic panel - ix metabolic or infective causes
ECG - rule out convulsive syncope
Mx of epilepsy
Valproate
Lamotrigine
Carbamazepine
Monotherapy 1st
Define Idiopathic Parkinson’s Disease
Neurodegenerative disorder characterised by cardinal features of
- resting tremor
- rigidity
- bradykinesia
- postural instability
Epidemiology of Idiopathic Parkinson’s disease
Most common neurodegenerative disorder
- prevalence of 1.6%
Incidence increases with age
Mean onset 65 years
Presentation of Idiopathic Parkinson’s Disease
Bradykinesia - slowness of movements, progressive reduction in amplitude of repeated movements, delay in initiating movements Resting tremor - 4-6Hz pill rolling tremor Cogwheel rigidity Postural instability Masked face - loss of facial movement and expression Hypophonia Micrographia Stooped posture Shuffling gait Conjugate gaze disorders Dementia Constipation, depression and fatigue Progressive symptoms
Ix for Idiopathic Parkinson’s Disease
Diagnosis made on Parkinson’s exam
- observation, basic movements, fine movements, tone, gait, pull test
Dopaminergic agent trial - improves symptoms
MRI brain - normal with age related changes
Functional neuroimaging - decreased basal ganglia dopamine uptake
Mx of Idiopathic Parkinson’s Disease
Levadopa + co-careldopa
- benefits last 5-10 years
- SE - excessive movements and nausea
Physical activity
- under supervision with falls prevention
Trihexyphenidyl or propranolol for tremor
DDx for Idiopathic Parkinson’s Disease
Essential tremor - fast, postural and kinetic, improves with rest, involves head and neck
Dystonic tremor - task-specific, flurries, thumb extension
Progressive supranuclear palsy - vertical gaze palsies, significant postural instability, midbrain atrophy on MRI
Multi-system atrophy - poor response to levodopa, autonomic dysfunction, pyramidal or cerebellar dysfunction
Lewy-body dementia - hallucinations and fluctuating mental state first
Drug induced parkinsonism
Define Amyotrophic Lateral Sclerosis
Most common motor neurone disease
Upper and lower motor neurone findings
Epidemiology of Amyotrophic Lateral Sclerosis
Mean onset is 57
Prevalence of 5 per 100,000
Pathophysiology of Amyotrophic Lateral Sclerosis
Progressive loss of cortical, bulbar and ventral cord motor neurones
After motor cell death, retrograde axonal degeneration follows
Subsequent denervation and reinnervation in corresponding muscles
Presentation of Amyotrophic Lateral Sclerosis
Upper extremity weakness Stiffness with poor coordination Spasticity, unsteady gait Painful muscle spasms Difficulty getting out of chairs Foot drop Head drop/stooped posture/lumbar lordosis Muscle atrophy Hyper-reflexia Dyspnoea Dysphagia Dysarthria
Ix for Amyotrophic Lateral Sclerosis
Generally diagnosed due to progression of symptoms and no other explanation
EMG - evidence of ongoing, chronic denervation
Repetitive nerve stimulation - modest decrease in motor action amplitude
MRI brain and spine - normal
Mx of Amyotrophic Lateral Sclerosis
Riluzole - slows disease progression - monitor LFTs every 3 months and neutrophils BiPAP - for resp symptoms Baclofen + physio - spasticity Supportive care
Differentials of Amyotrophic Lateral Sclerosis
Primary lateral sclerosis - isolated UMN disorder, weakness and spasticity
Progressive muscular atrophy - isolated LMN disorder, weakness and fasciculations
Define MS
Inflammatory CNS demyelination causing episodic neurological dysfunction in 2 areas
Types of MS
Relasping- remitting - active/not active within a specified time - assess annually
Progressive - primary (from onset) or secondary (after an initial relapsing course)
Epidemiology of MS
Incidence of 6 per 100,000
Commonly diagnosed aged 20-40
3 times more likely in females