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
Recognise the signs of encephalitis on physical examination
- Reduce consciousness
- Deteriorating GCS
- Seizures
- Pyrexia
Signs of Meningism:
o Neck stiffness
o Photophobia
o Kernig’s test positive
Signs of raised ICP:
o Cushing’s Response: hypertension + bradycardia + irregular breathing
o Papilloedema
Focal neurological signs
MMSE may reveal cognitive/psychiatric disturbance
Identify appropriate investigations for encephalitis and interpret the results
Bloods o FBC - high lymphocytes (indicates viral cause) o U&Es - SIADH may occur as a result of encephalitis o Glucose o Viral serology o ABG MRI/CT o Exclude mass lesion o HSV causes oedema of the temporal lobe on MRI Lumbar Puncture o High lymphocytes o High monocytes o High protein o Glucose is usually normal o Viral PCR EEG - may show epileptiform activity Brain biopsy (rarely needed)
Define epilepsy
• A tendency to recurrent unprovoked seizures
• You need to have had > 2 seizures for epilepsy to be diagnosed
• Definition of Seizure: paroxysmal synchronised cortical electrical discharges
• Types of Seizure
o Focal Seizure: seizure localised to specific cortical regions (e.g. temporal lobe seizure). These can be further divided into:
• COMPLEX partial seizure: consciousness is affected
• SIMPLE partial seizure: consciousness is NOT affected
o Generalised Seizure: seizures that affect the whole of the brain. It also affects consciousness. There are different types of generalised seizure:
• Tonic-clonic
• Absence
• Myoclonic
• Atonic
• Tonic
Explain the aetiology/risk factors of epilepsy
• Most cases are IDIOPATHIC
• Primary epilepsy syndromes (e.g. idiopathic generalised epilepsy)
• Secondary Seizures
o Tumour
o Infection (e.g. meningitis)
o Inflammation (e.g. vasculitis)
o Toxic/Metabolic (e.g. sodium imbalance)
o Drugs (e.g. alcohol withdrawal)
o Vascular (e.g. haemorrhage)
o Congenital abnormalities (e.g. cortical dysplasia)
o Neurodegenerative disease (e.g. Alzheimer’s disease)
o Malignant hypertension or eclampsia
o Trauma
• Common things that look like seizures
o Syncope
o Migraine
o Non-epileptiform seizure disorder (e.g. dissociative disorder)
• Pathophysiology of Seizures
o Result from an imbalance in the inhibitory and excitatory currents or neurotransmission in the brain
o Precipitants include anything that promotes excitation of the cerebral cortex
o Often it is unclear why the precipitants cause seizures
Summarise the epidemiology of epilepsy
- COMMON
- 1% of the general population
- Typical age of onset: CHILDREN and ELDERLY
Recognise the presenting symptoms of epilepsy
• NOTE: try and obtain a collateral history from a witness as well as the patient
• Key features to consider when taking a history from a potential epilepsy patient:
o Rapidity of onset
o Duration of episode
o Any alteration in consciousness?
o Any tongue-biting or incontinence?
o Any rhythmic synchronous limb jerking?
o Any post-ictal abnormalities (e.g. exhaustion, confusion)?
o Drug history (alcohol, recreational drugs)
• Focal Seizure Presentation
o Frontal Lobe Focal Motor Seizure
• Motor convulsions
• May show a Jacksonian march (when the muscular spasm caused by the simple partial seizure spreads from affecting the distal part of the limb towards the ipsilateral face)
• May show post-ictal flaccid weakness (Todd’s paralysis)
o Temporal Lobe Seizures
• Aura (visceral or psychic symptoms)
• Hallucinations (usually olfactory or affecting taste)
o Frontal Lobe Complex Partial Seizure
• Loss of consciousness
• Involuntary actions/disinhibition
• Rapid recovery
• Generalised Seizures
o Tonic-Clonic (Grand Mal)
• Vague symptoms before attack (e.g. irritability)
• Tonic phase (generalised muscle spasm)
• Clonic phase (repetitive synchronous jerks)
• Faecal/urinary incontinence
• Tongue biting
• Post-ictal phase: impaired consciousness, lethargy, confusion, headache, back pain, stiffness
o Absence (Petit Mal)
• Onset in CHILDHOOD
• Loss of consciousness but MAINTAINTED POSTURE
• The patient will appear to stop talking and stare into space for a few seconds
• NO post-ictal phase
o Non-Convulsive Status Epilepticus
• Acute confusional state
• Often fluctuating
• Difficult to distinguish from dementia
Recognise the signs of epilepsy on physical examination
- Depends on aetiology
* Patients tend to be normal in between seizures
Identify appropriate investigations for epilepsy
• Bloods o FBC o U&E o LFTs o Glucose o Calcium o Magnesium o ABG o Toxicology screen o Prolactin - shows a transient increase shortly after seizures • EEG o Helps to confirm diagnosis o Helps classify the epilepsy o Ictal EEGs are particularly useful (i.e. during a seizure) • CT/MRI o Shows structural, space-occupying or vascular lesions • Other investigations o If it is suspected to be a secondary seizure (e.g. due to infection)
Generate a management plan for epilepsy
• Treatment of STATUS EPILEPTICUS
o DEFINITION of Status Epilepticus: a seizure lasting > 30 mins or repeated seizure without recovery and regain of consciousness in between
o Although the definition states that the seizure must last > 30 mins, treatment is usually initiated early (after around 5-10 mins)
o ABC approach
o Check GLUCOSE (give glucose if hypoglycaemic)
o IV lorazepam OR IV/PR diazepam - REPEAT again after 10 mins if seizure does not terminate
o If seizures recur following the next dose of lorazepam or diazepam, consider IV phenytoin - an ECG monitor is required
• NOTE: other agents include phenobarbitone, levetiracetam and sodium valproate
o If this also fails, consider general anaesthesia (e.g. thiopentone) - intubation and mechanical ventilation required
o Treat the CAUSE (e.g. hypoglycaemia or hyponatraemia)
o Check plasma levels of anticonvulsants (because status epilepticus is often caused by lack of compliance with anti-epileptic medications)
• Treatment of newly diagnosed epilepsy
o Only start anti-convulsant treatment after > 2 unprovoked seizures
o FOCAL Seizure 1st Line: lamotrigine or carbamazepine
o GENERALISED Seizure 1st Line: sodium valproate
o Start treatment with only ONE anti-epileptic drug
o Other anti-convulsants: phenytoin, levetiracetam, clobazam, topiramate, gabapentin, vigabatrin
• Patient Education
o Avoid triggers
o Use seizure diaries
o Particular consideration for women of child-bearing age because the anti-epileptic drugs can have teratogenic effects
o Be careful of drug interactions (e.g. AEDs can reduce the effectiveness of the oral contraceptive pill)
• Surgery may be considered for refractory epilepsy
Identify possible complications of epilepsy
• Fractures from tonic-clonic seizures • Behavioural problems • Sudden death in epilepsy (SUDEP) • Complications of anti-epileptic drugs: o Gingival hypertrophy (phenytoin) o Neutropaenia and osteoporosis (carbamazepine) o Stevens-Johnson syndrome (lamotrigine)
Summarise the prognosis for patients with epilepsy
• 50% remission at 1 year
Define extradural haemorrhage
• Bleeding and accumulation of blood in the extradural space
Explain the aetiology / risk factors of extradural haemorrhage
TRAUMA
o Usually due to fracture of the temporal or parietal bones leading to rupture of the middle meningeal artery
Risk Factors
o Bleeding tendency
• E.g. haemophilia, anticoagulant therapy
Summarise the epidemiology of extradural haemorrhage
- UK incidence: 20/10,000
- 10% of severe head injuries
- Most commonly seen in YOUNG ADULTS
Recognise the signs of extradural haemorrhage on physical examination
- Head injury with temporary loss of consciousness
- Followed by lucid interval
- Followed by progressive deterioration in conscious level
Recognise the presenting symptoms of extradural haemorrhage
• Scalp trauma or fracture • Headache • Deteriorating GCS Signs of raised ICP o E.g. dilated, unresponsive pupil on the side of the injury Cushing's Reflex o Hypertension o Bradycardia o Irregular breathing
Identify appropriate investigations for extradural haemorrhage and interpret the results
• Urgent CT Scan
o Check for a haematoma
o Look for features of raised ICP (e.g. midline shift)
Define Guillain-Barre syndrome
• Acute inflammatory demyelinating polyneuropathy
Explain the aetiology/risk factors of Guillain-Barre syndrome
• An inflammatory process where antibodies after a recent infection react with self-antigen on myelin or neurons
• There is often no aetiological trigger identified (40% of cases are idiopathic)
• Other causes:
o Post-infection (1-3 weeks) - bacterial, HIV, herpes viruses
o Malignancy - e.g. lymphoma
o Post-vaccination
Summarise the epidemiology of Guillain-Barre syndrome
- UK incidence: 1-2/100,000
* Affects all age groups
Recognise the presenting symptoms of Guillain-Barre syndrome
• PROGRESSIVE symptoms
• < 1 month duration of:
o ASCENDING symmetrical limb weakness (lower > upper)
o ASCENDING paraesthesia
• Cranial nerve involvement (leading to, for example, dysphagia, dysarthria, facial weakness)
• Respiratory muscles may be affected in SEVERE cases
• Miller-Fisher Variant (RARE) = ophthalmoplegia, ataxia, arreflexia
Recognise the signs of Guillain-Barre syndrome on physical examination
• General MOTOR Examination
o Hypotonia
o Flaccid paralysis
o Arreflexia (ascending upwards from feet to head)
• General SENSORY Examination
o Impairment of sensation in multiple modalities (ascending from feet to head)
• Cranial Nerve Palsies
o Facial nerve weakness
o Abnormality of external ocular movements
o If pupil constriction is affected, consider botulism
• Type II Respiratory Failure
o Due to paralysis of respiratory muscles
• Autonomic Function
o Assess postural blood pressure change and arrhythmias
Identify appropriate investigations for Guillain-Barre syndrome
• Lumbar Puncture o HIGH protein o NORMAL cell count and glucose • Nerve Conduction Study o Reduced conduction velocity o NOTE: it may be normal in the early stages of the disease • Bloods o Anti-ganglioside antibodies in Miller-Fisher variant + 25% of Guillain-Barre cases • Spirometry o Reduced fixed vital capacity - suggests ventilatory weakness • ECG o Arrhythmias may develop
Define Horner’s Syndrome
• A condition that results from the disruption of the sympathetic nerves supplying the face resulting in a triad of: o Ptosis o Miosis o Anhydrosis o (and enophthalmos)
Explain the aetiology/risk factors of Horner’s syndrome
• It is caused by disruption of the sympathetic nerves • Causes o Strokes o Multiple sclerosis o Apical lung tumours o Lymphadenopathy o Basal skull tumours o Carotid artery dissection o Neck trauma
Summarise the epidemiology of Horner’s syndrome
- RARE
* Important sign that is associated with various diseases (most notably, Pancoast tumours)
Recognise the presenting symptoms of Horner’s syndrome
- Inability to open the eye fully on the affected side
- Loss of sweating on affected side
- Facial flushing
- Orbital pain/headache
- Other symptoms based on CAUSE
Recognise the signs of Horner’s syndrome on physical examination
- Ptosis
- Miosis
- Anhydrosis
- Enophthalmos
Identify appropriate investigations for Horner’s syndrome
- Investigations are directed towards figuring out the underlying cause
- CXR - apical lung tumour
- CT/MRI - cerebrovascular accidents
- CT angiography - dissection
Generate a management plan for Horner’s syndrome
- Horner’s syndrome is a sign not a disease in itself
- So, the management depends on the cause (e.g. management for carotid dissection is very different to management of apical lung tumours)
Identify possible complications of Horner’s syndrome
• Depends on cause
Summarise the prognosis of Horner’s syndrome
• Depends on the cause
Define Huntington’s disease
• Autosomal dominant trinucleotide repeat disease characterised by progressive chorea and dementia, typically commencing in middle age
Explain the aetiology/risk factors of Huntington’s disease
- The huntingtin gene codes for a protein called huntingtin
- In the huntingtin gene there is a trinucleotide repeat expansion (CAG) that results in toxic gain of function
- Autosomal DOMINANT
- Earlier age of onset with each successive generation
Summarise the epidemiology of Huntington’s disease
• Average age of onset: 30-50 yrs
Recognise the presenting symptoms of Huntington’s disease
• Family history • INSIDIOUS onset in middle-age • Progressive • Fidgeting • Clumsiness • Involuntary, jerky, dyskinetic movements often accompanied by grunting and dysarthria • EARLY COGNITIVE CHANGES: o Lability o Dysphoria (a state of unease or generalised dissatisfaction with life) o Mental inflexibility o Anxiety o Develops into dementia • LATER STAGES: o Rigid o Akinetic o Bed-bound • Enquire about drug history (especially cocaine and anti-psychotics)
Recognise the signs of Huntington’s disease on physical examination
- Chorea
- Dysarthria
- Slow voluntary saccades
- Supranuclear gaze restriction
- Parkinsonism
- Dystonia
- MMSE shows cognitive and emotional deficits
Identify appropriate investigations for Huntington’s disease
• Genetic Analysis
o Diagnostic if there are > 39 CAG repeats in the HD gene
o Reduced penetrance leads to an intermediate number of CAG repeats
• Imaging
o Brain MRI or CT may show symmetrical atrophy of the striatum and butterfly dilation of the lateral ventricles
• Bloods
o To exclude other pathology
Define hydrocephalus
• Enlargement of the cerebral ventricular system.
• It can be subdivided into obstructive and non-obstructive
o AKA communicating and non-communicating
• Hydrocephalus ex vacuo = apparent enlargement of the ventricles as a compensatory change due to brain atrophy
Explain the aetiology/risk factors of hydrocephalus
• Abnormal accumulation of CSF in the ventricles can be caused by:
o OBSTRUCTIVE: Impaired outflow of the CSF from the ventricular system
• Lesions of the 3rd and 4th ventricle or cerebral aqueduct
• Posterior fossa lesions (e.g. tumour) compressing the 4th ventricle
• Cerebral aqueduct stenosis
o NON-OBSTRUCTIVE: Impaired CSF reabsorption into the subarachnoid villi
• Tumours
• Meningitis
• Normal Pressure Hydrocephalus - idiopathic chronic ventricular enlargement. The long white matter tracts are damaged leading to gait and cognitive decline
Summarise the epidemiology of hydrocephalus
• Bimodal age distribution
o YOUNG - congenital malformations and brain tumours
o ELDERLY - strokes and tumours
Recognise the presenting symptoms of hydrocephalus
• Obstructive Hydrocephalus o Acute drop in conscious level o Diplopia • Normal Pressure Hydrocephalus o Triad of symptoms: • Dementia • Gait disturbance • Urinary incontinence
Recognise the signs of hydrocephalus on physical examination
• Obstructive Hydrocephalus o Low GCS o Papilloedema o 6th nerve palsy • 6th nerve has the longest intracranial path of all the cranial nerves and so is most susceptible to palsy due to raised ICP o NEONATES:
• Increased head circumference • Sunset sign (downward conjugate deviation of the eyes) • Normal Pressure Hydrocephalus o Cognitive impairment o Gait apraxia (shuffling) o Hyperreflexia
Identify appropriate investigations for hydrocephalus
• CT Head
o FIRST-LINE for detecting hydrocephalus
o May also pick up the cause (e.g. tumour)
• CSF
o From ventricular drain or lumbar puncture
o May indicate pathology (e.g. tuberculosis)
o Check MC&S, protein and glucose
• Lumbar Puncture
o IMPORTANT: contraindicated if raised ICP
o Therapeutic in normal pressure hydrocephalus
Define meningitis
• Inflammation of the leptomeningeal (pia and arachnoid mater) coverings of the brain, most commonly due to infection
Explain the aetiology / risk factors of meningitis
BACTERIAL Neonates • Group B streptococci • Escherichia coli • Listeria monocytogenes Children • Haemophilus influenzae • Neisseria meningitidis • Streptococcus pneumoniae Adults • Neisseria meningitidis • Streptococcus pneumoniae • Tuberculosis Elderly • Streptococcus pneumoniae • Listeria monocytogenes
VIRAL o Enteroviruses o Mumps o HSV o VZV o HIV
Fungal o Cryptococcus (common cause of meningitis in HIV patients)
Others
o Aseptic meningitis (not due to microbes)
o Mollaret’s meningitis (recurrent benign lymphocytic meningitis)
RISK FACTORS o Close communities (e.g. college halls) o Basal skull fractures o Mastoiditis o Sinusitis o Inner ear infections o Alcoholism o Immunodeficiency o Splenectomy o Sickle cell anaemia o CSF shunts o Intracranial surgery
Summarise the epidemiology of meningitis
• UK: 2500 notifications/yr
