Neurology (2) Flashcards
Define multiple sclerosis
A chronic, relapsing-remitting demyelinating disorder caused by autoimmune destruction of myelin and oligodendrocytes in the CNS, leading to multiple transient neurological defects separated in space and time.
Summarise the aetiology of multiple sclerosis
Aetiology is unknown
Genetic factors - female, HLA-DR2
Environmental factors - infection, vitamin D deficiency
Autoimmune-mediated damage to myelin sheaths results in impaired axonal conduction
Risk factors: EBV exposure Prenatal vitamin D levels Autoimmune Disease Female Smoking
Summarise the epidemiology of multiple sclerosis
Most common in women
Age of presentation usually 20-40 years old
What are the presenting symptoms of multiple sclerosis?
Multiple transient neurological symptoms spread over space and time
Symptoms depend on where is affected
Charcot’s neurological triad - dysarthria, nystagmus, intention tremor
Optic neuritis:
Acute onset unilateral loss of visual acuity and colour perception with RAPD, preceded by pain
Sensory:
Parasthesia
Numbness
Burning
Motor: Ataxia Muscle weakness Spasm Stiffness Heaviness
ANS:
Constipation
Urinary incontinence
Depression
Psychosis
Lhermitte’s sign - electric shock down back and radiates to limbs when bending neck forwards
Uhthoff’s Sign: worsening of neurological symptoms as the body gets overheated from hot weather, exercise, saunas, hot tubs etc.
What are the signs on physical examination of multiple sclerosis?
Optic Neuritis:
Impaired Visual Acuity
Loss of colour vision
Relative Afferent Pupillary Defect - Both pupils contract (unaffected side) and both pupils dilate (affected side)
Fundoscopy: Swollen Optic Head (active disease) & Optic Atrophy (chronic disease)
Visual Field Testing: Central scotoma (blind sport in normal visual field if optic nerve is affected Field defects if optic radiations are affected
Internuclear Ophthalmoplegia:
Lateral horizontal gaze causes failure of adduction of the contralateral eye
Indicates lesion of the contralateral medial longitudinal fasciculus
Sensory: Paraesthesia
Motor: UMN signs
Cerebellar: Limb ataxia (intention tremor, past-pointing, dysmetria), dysdiadochokinesia, ataxic wide-based gait and scanning speech
What are the appropriate investigations for multiple sclerosis?
McDonald criteria = 2 or more CNS lesions with corresponding symptoms, separated in time and space
MRI head - paraventricular plaques (hyperintensities)
MRI spinal cord - demyelinating lesions
CSF - increased IgG, electrophoresis shows unmatched oligoclonal bands
Evoked Potentials - Visual, auditory and somatosensory evoked potentials may show delayed conduction velocity
Define encephalitis
Inflammation of the brain parenchyma leading to acute neurological dysfunction such as seziures, coma, personality changes, cranial nerve palsies, speech and motor problems.
Summarise the aetiology of encephalitis
Viruses most common: HSV - most common Enterovirus Varicella Zoster Virus Measles Mumps EBV Adenovirus Coxsackie HIV
Bacteria:
Listeria monocytogenes
Mycobacteria
Non-Viral causes (RARE): Syphilis, Staphylococcus aureus
In immunocompromised patients: CMV, Toxoplasmosis, Listeria
AI or Paraneoplastic: Associated with certain antibodies (e.g. anti-NMDA, anti-VGKC)
Summarise the epidemiology of encephalitis
No gender predominance
Age bimodal distribution - under 1 year old and over 65
What are the presenting symptoms of encephalitis?
SUBACUTE ONSET - HOURS TO DAYS Fever Headache Seizure Coma Drowsiness Fatigue Malaise Confusion Altered consciousness Altered brain function - personality changes Vomiting Meningism: Neck stiffness, photophobia Focal neurological symptoms (e.g. dysphagia, hemiplegia)
What are the signs on physical examination of encephalitis?
Reduced consciousness Deteriorating GCS MMSE may reveal cognitive/psychiatric disturbance Seizures Pyrexia/fever
Signs of Meningism:
Neck stiffness
Photophobia
Kernig’s test positive - lie supine, flex hip and extend knee causes pain
Signs of raised ICP:
Cushing’s Response: triad - hypertension, bradycardia, irregular breathing
Papilledema
Focal neurological signs (e.g. dysphagia, hemiplegia)
What are the appropriate investigations for encephalitis?
FBC - elevated WCC
Viral serology
MRI brain - increased intensities in frontotempr=oral region suggests HSV
CT - check for raised ICP
If no raised ICP - Lumbar puncture
CSF culture - high lymphocytes, increased monocytes and protein, normal glucose, elevated RBCs
Blood cultures
CSF PCR can show viral causes
Define stroke
An acute, permanent neurological deficit lasting >24 hours.
Summarise the aetiology of stroke
Ischaemic stroke - most common
Acute blockage of artery or critical stenosis of artery, preventing blood flow to brain
Thromobotic - atherosclerosis, fibromuscular dysplasia
Embolic - AF, atheroembolic, DVT passing through patent foramen ovale
Hypoxic - sepsis, infants, drowning
Hypotension
Haemorrhagic stroke: Burst blood vessel Intracerebral haemorrhage SAH - due to ruptured berry aneurysm Hypertension Amyloid angiopathy Arteriovenous Malformation Charcot Bouchard microaneurysm rupture (aneurysms within the brain vasculature that occur in small blood vessels)
What are the risk factors of stroke?
Ischaemic stroke RF: Hypertension Smoking Dislipidaemia Family history Increased age Diabetes AF Carotid artery stenosis
Haemorrhagic stroke RF: Increased age FHx Haemophilia Anticoagulation Hypertension Male
Summarise the epidemiology of stroke
Common
3rd most common cause of death in industrialised countries
Age 70+
What are the presenting symptoms of stroke?
Sudden onset Numbness Muscle weakness Visual disturbance Sensory or cognitive impairment Impaired coordination and/or consciousness Head or neck pain
What are the signs on physical examination of stroke?
Anterior Cerebral:
Lower limb weakness & Confusion
Middle Cerebral: Arms and face more than lower limbs Facial weakness Hemiparesis Hemisensory loss Apraxia Hemineglect (parietal lobe) Receptive or expressive dysphasia (Wernicke's and Broca's areas respectively) Quadrantopia (if superior or inferior optic radiations are affected)
Posterior Circulation: hemianopia, vertigo, ipsilateral ataxia, deafness, facial weakness
Intracerebral: headache, meningism, focal neurological signs, nausea/vomiting, signs of raised ICP, seizures
Initially: flaccid paralysis
Later: hyperreflexia, spastic paralysis
What are the appropriate investigations for stroke?
Bloods: FBC U&E’s Glucose Clotting profile (check if thrombophilia especially in young patients) Lipids Cardiac enzymes
ECG: Check for arrhythmias that may be the source of the clot (AF)
CT Head Scan: Distinguish between ischaemic and haemorrhagic stroke
MRI-Brain: Higher sensitivity for infarction but less available
Echo: Identify cardiac thrombus, endocarditis and other cardiac sources of embolism
Carotid Doppler Ultrasound: Check for carotid artery disease (e.g. atherosclerosis)
CT Cerebral Angiogram: Detect dissections or intracranial stenosis
What is the management of stroke?
Ischaemic:
<4.5 hours - CT head to exclude haemorrhage, thrombolysis with IV tissue plasminogen activator
> 4.5 hours:
Aspirin 300mg and clopidogrel - prevent further thrombosis
Swallow assessment
GCS monitoring
Heparin anticoagulation considered if there is a high risk of emboli recurrence or stroke progression (carotid dissection, recurrent cardiac emboli)
Thromboprophylaxis
Secondary Prevention - Aspirin and dipyridamole, Warfarin anticoagulation (AF)
Control risk factors:
Hypertension
Hyperlipidaemia
Treat carotid artery disease
Haemorrhagic stroke:
Surgery - clip or coil to block bleed
Craniotomy to reduce increased ICP
Nimodipine CCB
What are the possible complications of stroke?
Cerebral oedema (increased ICP) Immobility Infections DVT Cardiovascular events Death
Summarise the prognosis of stroke
10% mortality in the 1st month
Up to 50% survivors will be dependent
10% recurrence 1 year
Define motor neurone disease
Progressive neurodegenerative disease involving the motor cortex, anterior horn and cranial nerves, causing selective death and loss of neurones. It causes a combination of upper and lower motor neuron signs but NO sensory changes, sphincter disturbance or eye movement changes.
What are the types of motor neurone disease?
Amyotrophic lateral sclerosis - most common (80%)
Affects anterior horn and lateral corticospinal tract
LMN and UMN signs present
Muscle weakness, hyperreflexia, fasciculations, upgoing plantars, muscle atrophy
Progressive bulbar palsy
Affects cranial nerves IX - XII
Dysarthria, dysphagia, brisk jaw reflex, wasting and fasciculation of tongue
Progressive muscular atropy
LMN signs
Weakness, wasting, fasciculations, foot drop
Distal muscles affected first
Progressive lateral sclerosis
UMN signs
Spastic leg weakness
Summarise the aetiology of motor neurone disease
Unknown
Thought to be free radical damage and glutamate excitotoxicity
Genetic predisposition - SOD1 mutation on chromosome 21
Motor neurone degeneration
Summarise the epidemiology of motor neurone disease
Men affected more (3:2)
Average age of presentation 60 years old
5-10% have family history in autosomal dominant inheritence
What are the presenting symptoms of motor neurone disease?
Muscle weakness Muscle fasciculation Dysarthria Dysphagia Weak grip - difficulty turning door handle Weak shoulder abduction - difficulty washing hair Foot drop Proximal myopathy Stumbling spastic gait
What are the signs on physical examination of motor neurone disease?
UMN signs - hyperreflexia, spastic paralysis, weakness, upgoing plantars
LMN signs - weakness, fasciculations, atrophy, absent reflexes
What are the appropriate investigations for motor neurone disease?
No diagnostic investigation
EMG - denervation features
Nerve conduction - normal
Brain/spine MRI - exclude structural cause
Lumbar puncture - exclude infectious aetiology
Bloods - CK, ESR, anti-GMI ganglioside antibodies elevated
Define epilepsy
A tendency to recurrent, unprovoked and unpredictable seizures (a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous activity in the brain)
Types of seizures:
Partial - only affect part of the brain
Simple partial seizure - consciousness not affected
Complex partial seizure - consciousness affected
Generalised - affect both hemispheres and consciousness Atonic Tonic-clonic Myoclonic Absence Tonic Clonic
Summarise the aetiology of epilepsy
Increased excitation
Decreased inhibition
Idiopathic Secondary: Tumour Stroke Infection Injury Inflammation (MS, vasculitis) Toxic/Metabolic (sodium imbalance) Drugs (alcohol withdrawal, benzodiazepine) Vascular (haemorrhage, infarction) Malignant HTN or eclampsia Congenital abnormalities (cortical dysplasia) Neurodegenerative disease (Alzheimer's disease)
What are the risk factors of epilepsy?
Age (young & elderly) Family History Head Injury Stroke & Other vascular diseases Dementia Brain Infections Seizures in Childhood
