Nervous System Flashcards
What is Bell’s palsy?
Idiopathic lower motor neurone facial (VII) nerve palsy
What is the aetiology of Bell’s palsy?
- Idiopathic - 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?
- Unknown - 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 - Agitation - 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 Positive symptoms: - Aggression, wandering, agitation, hallucinations, flight of ideas, logorrhoea: incoherent talkativeness Negative symptoms: - 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
What is a focal seizure?
Seizure localised to specific cortical regions, such as temporal lobe seizures, frontal lobe seizures, occipital seizures, complex partial seizures
What is a generalised seizure?
Seizures which affect consciousness typically tonic-clonic, absence attacks myoclonic, atonic (drop attacks) or tonic seizures
What is the aetiology of epilepsy?
Majority of cases are idiopathic - Primary epilepsy syndromes (e.g. idiopathic generalised epilepsy, temporal lobe epilepsy, juvenile myoclonic epilepsy - Secondary seizures (symptomatic epilepsy): (Tumour, infection:meningitis, encephalitis, abscess, Inflammation: vasculitis, rarely MS, toxic/metabolic: sodium imbalance, hypocalcaemia, drugs: alcohol, benzos, vascular: haemorrhage, infarction, congenital abnormalities: corticol dysplasia, neurodegenerative disease: Alzheimer’s, malignant hypertension, trauma - Common seizure mimics: syncope, migraine, non-epileptiform seizure disorder
What is the pathophysiology of epilepsy?
- Seizures result from an imbalance in the inhibitory and excitatory currents (e.g. Na+ or K+ ion channels) or neurotransmission (i.e. glutamate or GABA neurotransmitters) in the brain - Precipitants include any trigger which promotes excitation of the cerebral cortex (e.g. flashing lights, drugs, sleep deprivation, metabolic) but often cryptogenic
What is the epidemiology of epilepsy?
- Common - Prevalence in 1% of general population - Peak age of onset is in early childhood or in the elderly
What should be obtained from the history of a patient with epilepsy?
Obtain history from a witness as well as a patient 1) Rapidity of onset 2) Duration of episode 3) Any alteration of consciousness 4) Any tongue-biting of incontinence 5) Any rhythmic synchronous limb jerking? 6) Any post-ictal period? 7) Drug history (alcohol, recreational drugs
What are the presenting symptoms of focal seizures?
- Frontal lobe focal motor seizures: Motor convulsions. May demonstrate Jacksonian march (spasm spreading from mouth or digit). There may be post-ictal flaccid weakness (Todd’s paralysis) - Temporal love seizures: Aura (visceral and psychic symptoms: fear or deja-vu sensation), Hallucinations (olfactory, gustatory) - Frontal lobe complex partial seizures: Loss of consciousness with associated automatisms and rapid recover
What are the presenting symptoms of generalised seizures?
- Tonic-clonic (grand mal): Vague symptoms before an attack (e.g. irritability), followed by tonic phase (generalised muscle spasm), followed by a clonic phase (repetitive synchronous jerks), and associated faecal or urinary incontinence, tongue biting. After a seizure, there is often impaired consciousness, lethargy, confusion, headache, back pain, stiffness - Absence (petit mal): Usual onset in childhood. Characterised by loss of consciousness but maintained posture (pt stops talking and stares into space for seconds), blinking of rolling up of eyes with other repetitive motor actions (e.g. chewing). No postictal phase - Non-convulsive status epilepticus: Acute confusional state. Often fluctuating. Difficult to distinguish from dementia
What are the signs of epilepsy on examination?
- Depends on aetiology, usually normal between seizures - Look for focal abnormalities indicative of brain lesins
What are the investigations for epilepsy?
- Blood: FBC, U&E, LFTs, glucose, Ca, Mg, ABG, toxicology screen, prolactin (transient increase shortly after a true seizure) - EEG: Helps confirm or refute the diagnosis, assists in classifying the epileptic syndrome. Usually performed inter-ictally and often normal and does not rule out epilepsy. Ictal EEG’s combined with video telemetry are more useful but requires adequate facilities - CT/MRI: for structural, space-occupying and vascular lesions - Other: Particularly for secondary seizures according to suspected aetiology e.g. lumbar puncture, HIV serology
How is status epilepticus (seizure lasting more than 30mins, failure to regain consciousness) managed?
Although defined as more than 30min or repeated seizures with failure to regain consciousness, treatment is often initiated in 5-10 mins as early treatment has higher treatment success - Resuscitate and protect airway, breathing and circulation - Check glucose and give if hypoglycaemic. Consider thiamine - IV lorazepam or IV or PR diazepam (repeat once after 15 mins if needed). If seizures recur fail to respond, IV phenytoin (15mg/kg under ECG monitoring). Alternative IV agents include phenobarbitone, levetiracetam or sodium valproate - If these measures fail, consider general anaesthesia. Requires intubation and mechanical ventilation - Treat the cause e.g. correct hypoglycaemia or hyponatraemia - Check plasma levels of all anticonvulsants
What pharmacological treatment is used to manage epilepsy?
- Only start anti-convulsant therapy after more than 2 unprovoked seizures - There are numerous anti-convulsant agents, but SANAD trial suggests lamotrigine or carbamepine as first line treatment for focal seizures, and sodium valproate for generalised seizure - Other agents used include phenytoin, levetiracetam, clobazam, tropiramate, gabapentin, vigabatrin, ethrosuximide (absence) - Start treatment with single anti-epileptic drug (AED)
What patient education is advised in order to manage epilepsy?
- Patient education, avoid triggers (e.g. alcohol), encourage seizure diaries - Recommend supervision for swimming or climbing, driving only permitted if seizure free for 6 months - Women of childbearing age should be counseled regarding possible teratogenic effects of AEDs and should consider taking supplemental folate to limit the risk - Drug interactions e.g. enzyme-inducing AEDs can limit the effectiveness of oral contraception
How does surgery manage epilepsy?
For refractory epilepsy - Removal of definable epileptogenic focus (determined from detailed EEG, intracortical recordings, ictal SPECT, neuropsychometry) - Alternatively, vagus nerve stimulator
What are the possible complications of epilepsy?
- Fractures with tonic-clonic seizures - Behavioural problems - Sudden death in epilepsy (SUDEP) - Complications of AEDs (e.g. gingivial hypertrophy with phenytoin, neutropenia or osteoporosis with carbamazepine, Steven’s-Johnson syndrome with lamotrigine)
What is the prognosis for epilepsy?
- 50% remission at 1 year - Mortality 2 in 100,000/year, directly related to seizure of secondary to injury
What is Guillain-Barre syndrome?
Acute inflammatory demyelinating polyneuropathy
What is the aetiology of Guillain-Barre syndrome?
An inflammatory process where antibodies after a recent infection reacts with self-antigen on myelin or neurons. There are rare axonal variants with no demyelination. Often no-aetiological trigger is identified (idiopathic in about 40%) , in other cases: - Post-infection (1-3 weeks): bacterial (e.g. Campylobacter jejuni), HIV, herpes viruses (e.g. zoster, CMV) - Malignancy (lymphoma, Hodgkin’s disease) - Post-vaccination
What is the epidemiology of Guillain-Barre syndrome?
Annual incidence is 1-2 in 100,000. Affects all age groups
What are the presenting symptoms of Guillain-Barre syndrome?
Progressive symptoms of less than 1 month duration: - Ascending symmetrical limb weakness (lower more than upper) - Ascending paraesthesia
What are the signs of Guillain-Barre syndrome on examination?
General motor examination: Hypotonia, flaccid paralysis, arreflexia (typically ascending upwards from feet to head) - General sensory examination: Impairment of sensation in multiple modalities (typically ascending upwards from feet to head) - Cranial nerve palsies (less frequently): Facial nerve weakness (lower motor neurone pattern), abnormality of external ocular movements, signs of bulbar palsy. If pupil constriction is affected, consider boltulism - Type II respiratory failure: Important to identify early (e.g. C02 flap, bounding pulse drowsiness). Can be insidious and needs regular assessment - Autonomic function: Assess for postural BP change and arrhythmias
What are the investigations for Guillain-Barre syndrome?
- Lumbar puncture: Raised CSF protein, cell count and glucose normal - Nerve conduction study: Decreased conduction velocity or conduction block, but can be normal in the early phase of the disease - Blood: Anti-ganglioside antibodies are positive in Miller-Fish variant and 25% of Guillain-Barre syndrome cases: consider C.jejuni serology - Spirometry: Decreased fixed vital capacity indicated ventilatory weakness - ECG: Arrhythmias may develop
What is Horner’s syndrome?
Combination of symptoms that arises when the sympathetic trunk is damaged
What is the aetiology of Horner’s syndrome?
- Acquired due to disease but may be congenital (inborn, associated with heterochromatic iris) or iatrogenic - Central: Syringomyelia, MS, Encephalitis, Brain tumours, Lateral medullary syndrome - Preganglionic: Cervical rib, thyroid carcinoma, thyroidectomy, goiter - Postganglionic: Cluster headache, middle ear infection - Results from lesion to sympathetic pathways that supply head and neck
What are the presenting symptoms of Horner’s syndrome?
- Partial ptosis - Anhidrosis - Upside down ptosis (slight elevation of the lower lid)
What are the signs of Horner’s syndrome on examination?
- Miosis - Pseudoendopthalmos - Pupillary dilation lag - Loss of ciliospinal reflex - Bloodshot conjuctiva, depending on site of lesion - Unilateral straight hair (in congenital Hornery’s syndrome), hair on affected side may be straight in some cases - Heterochromia iridum (congenital)
What are the investigations for Horner’s syndrome?
- Cocaine drop test - Paredrine test: helps localise cause of miosis - Dilation lag test
How is Horner’s syndrome managed?
No specific treatment - Often it disappears when an underlying medical condition is effectively treated
What are the possible complications of Horner’s syndrome?
- Anisocoria - Enopthalmos - Hypohidrosis - Blepharoptosis - Pupillary constriction
What is the prognosis of Horner’s syndrome?
Depends on whether treatment of cause is successful
What is Huntington’s disease?
Autosomal dominant trinucleotide repeat disease characterised by progressive chorea and dementia, typically commencing in middle age
What is the aetiology of Huntington’s disease?
- Huntingtin gene is located on chromosome 4p and codes for the protein hungtingtin - In huntingtin gene, there is an extended trinucleotide repeat expansion (CAG) resulting in a toxic gain of function - Disease is inherited in an autosomal dominant pattern and exhibits anticipation (earlier age of onset in each successive generation)
What is the epidemiology of Huntington’s disease?
Worldwide prevalence eight in 100,000 - Average onset 30-50 years - Rare in East Asian populations (particularly Japan)
What are the presenting symptoms of Huntington’s disease?
- Family history of Huntington’s disease - Insidious onset in middle-age of progressive fidgeting and clumsiness, developing into involuntary, jerky, dyskinetic movements often accompanied by grunting and dysarthia - In late disease, the patient may become rigid, akinetic and bed-bound - Early cognitive, emotional and behavioural changes are dominated by lability, dysphoria, mental inflexibility, anxiety, leading on to dementia - Inquire about drug history (especially cocaine, anti-psychotics)
What are the signs of Huntington’s disease on examination?
- Classically, patient present with chorea and dysarthria - Slow voluntary saccades and supranuclear gaze restriction - Other presentation include parkinsonism and dystonia (especially in juvenile-onset disease) - Mental state examination reveals cognitive and emotional deficits
What are the investigations for Huntington’s disease?
- Genetic analysis: Diagnostic if more than 39 CAG repeats in HD gene. Intermediate repeat lengths (27-39) exist with reduced penetrance - Imaging: Brain MRI or CT may show symmetrical atrophy of the striatum (particularly the caudate nuclei) and butterfly dilation of the lateral ventricles - Bloods: May be necessary to exclude other pathology: caeruloplasmin, anti-nuclear antibodies blood film (acanthocytes), TFT, ESR
What is hydrocephalus?
- Enlargement of the cerebral ventricular system - Subdivisable into obstructive and non-obstructive (or communicating or non-communicating - Hydrocephalus ex vacuo is a term used to describe apparent enlargement of ventricles but this is a compensatory change due to brain atrophy
What is the aetiology of hydrocephalus?
Abnormal accumulation of CSF in the ventricles can be caused by 1) Impaired outflow of the CSF from ventricular system (obstructive) - Lesions of the third ventricle, fourth ventricle, cerebral aqueduct - Posterior fossa lesions (e.g. tumour, blood) compressing the fourth ventricle - Cerebral aqueduct stenosis 2) Impaired CSF resorption in the subarahnoid villi (non-obstructive) - Tumours - Meningitis (typically tuberculosis) - Normal pressure hydrocephalus (NPH) is the idiopathic chronic ventricular enlargement. The long white matter tract (corona radiata, anterior commisure) are damaged causing gait and cognitive decline)
What is the epidemiology of hydrocephalus?
- Bimodal age distribution - Congenital malformations and tumours in the young, tumours and stroked in the elderly
What are the presenting symptoms of hydrocephalus?
- Obstructive hydrocephalus: Acute drop in conscious level. Diplopia. - NPH: Chronic cognitive decline falls, urinary incontinence
What are the signs of hydrocephalus on examination?
- Obstructive: Impaired GCS, papilloedema, VI nerve palsy (‘false localising sign’ of increased ICP). In neonates, the head circumference may enlarge, and ‘sunset sign’ (downward conjugate deviation of eyes) - NPH: Chronic cognitive decline, Gait apraxia (shuffling), Hyperreflexia
What are the investigations for hydrocephalus?
- CT head: First line investigation to detect hydrocephalus, may also detect the cause (e.g. tumour in the brainstem) - CSF: Obtained from ventricular drains or lumbar puncture may indicate an underlying pathology (e.g. tuberculosis). Check for MC&S, protein, glucose (CSF and plasma) - Lumbar puncture: This is contra-indicated in obstructive hydrocephalus as can cause tonsilar herniation and death. May be necessary in NPS as a therapeutic trial
What is a lumbar puncture?
Medical procedure in which a needle is inserted into the spinal canal, most commonly to collect CSF for diagnostic testing
What are the indications for a lumbar puncture?
- Diagnostic: Analysis of CSF may exclude infectious, inflammatory and neoplastic disease affecting the CSF. Meningitis most common. Detects whether someone has Stage 1 or 2 trypanosoma bucrei - Therapeutic: Inject medications into CSF particularly spinal anaesthesia or chemotherapy
What are the possible complications of lumbar puncture?
- Post spinal headache with nausea - Paresthesia in leg: due to contact between the side of lumbar puncture needle and a spinal nerve root - Serious but rare: Epidural bleeding, adhesive arachnoiditis, trauma to spinal cord, paraplegia