Neuroscience Flashcards
What is Bell’s palsy?
An acute, unilateral, idiopathic, facial nerve paralysis that fully evolves within 72 hours
What is the aetiology of Bell’s palsy?
Viral which is strongly associated with the herpes simplex virus (type 1)
What is the epidemiology of Bell’s palsy?
Peak incidence is 20-40 years
More common in pregnant women
What are the risk factors for Bell’s palsy?
Pregnancy (x3)
Diabetes (x5)
What are the features of Bell’s palsy?
- Lower motor neuron facial nerve palsy - forehead affected (in contrast, an UMN lesion ‘spares’ the upper face)
- Patients may also notice post-auricular pain (may precede paralysis), altered taste, dry eyes, hyperacusis
What are the investigations for Bell’s palsy?
- Clinical diagnosis: acute, unilateral facial palsy, with an otherwise normal physical examination
- Tests to rule out other causes e.g. Ramsay Hunt syndrome (VZV), CT for stroke or SOL
What are the causes of 7th nerve palsy?
- Bell’s palsy
- Ramsay Hunt syndrome
- Lyme disease
- Brainstem lesions: stroke, tumour, MS
- Cerebellopontine tumours: acoustic neuromas
- Systemic disease: DM, Guillain-Barre
What differentiates Lyme disease, Guillain–Barré, sarcoid, and trauma from Bell’s palsy?
They all often present with bilateral weakness
What is the management for Bell’s palsy?
- All patients should receive oral prednisolone within 72 hours of onset of Bell’s palsy
- Antiviral treatment in combination with a corticosteroid may be of small benefit, but seek specialist advice if this is being considered - NICE
- Eye care to prevent exposure keratopathy: prescription of artificial tears and eye lubricants and microporous tape for night if unable to close
What is the follow up for Bell’s palsy?
- If the paralysis shows no sign of improvement after 3 weeks, refer urgently to ENT
- Referral to plastic surgery may be appropriate for patients with more long-standing weakness e.g. several months
What is the prognosis for Bell’s palsy?
Most people with Bell’s palsy make a full recovery within 3-4 months
If untreated around 15% of patients have permanent moderate to severe weakness
What are central nervous system tumours?
Primary tumours arising from any of the brain tissue types
What is the most common type of brain tumour?
Metastatic brain cancer
Often multiple and not treatable with surgical intervention
Tumours that most commonly spread to the brain include:
- Lung (most common)
- Breast
- Bowel
- Skin (namely melanoma)
- Kidney
What is the most common primary brain tumour in adults?
Glioblastoma multiforme
What are the features of glioblastomas on imaging?
- Solid tumours with central necrosis and a rim that enhances with contrast
- Disruption of the blood-brain barrier and therefore are associated with vasogenic oedema
What are the histological features of glioblastomas?
Pleomorphic tumour cells border necrotic areas
What is the management and prognosis of glioblastomas?
Surgical with postoperative chemotherapy and/or radiotherapy Dexamethasone is used to treat the oedema
Prognosis is poor ~ 1 year
What are the second most common primary brain tumours?
Meningiomas
What are meningiomas?
Typically BENIGN, extrinsic tumours of the CNS
They arise from the arachnoid cap cells of the meninges and are typically located next to the dura
Cause symptoms by compression rather than invasion
What are the histological features of meningiomas?
Spindle cells in concentric whorls and calcified psammoma bodies
What is the management plan for a meningioma?
Investigation is with CT (will show contrast enhancement) and MRI
Treatment will involve either observation, radiotherapy or surgical resection
What is the most common primary brain tumour in children?
Astrocytomas
What are the common CNS tumours?
60% = Glioma and metastatic disease
20% = Meningioma
10% = Pituitary lesions
What are some of the common features of CNS tumours?
- Headache or vomiting (raised intracranial pressure)
- Epilepsy (focal or generalized)
- Focal neurological deficits (dysphagia, hemiparesis, ataxia, visual field defects, cognitive impairment)
- Personality change
How to symptoms of CNS tumours present depending on site of tumour?
Tumours arising in right temporal and frontal lobe may reach considerable size before becoming symptomatic
Whereas tumours in the speech and visual areas will typically produce early symptoms
What is the diagnostic investigation of choice for CNS tumours?
MRI scan - provide best resolution
What is the management plan for CNS tumours?
- Usually surgery - even if tumour cannot be completely resected conditions such as rising ICP can be addressed with tumour debulking → survival and quality of life prolonged
1a. Curative surgery can usually be undertaken with lesions such as meningiomas
1b. *Gliomas have a marked propensity to invade normal brain and resection of these lesions is nearly always incomplete (hence poor prognosis)
What are vestibular schwannomas?
Previously termed acoustic neuroma
Benign tumour arising from the eighth cranial nerve (vestibulocochlear nerve)
Often seen in the cerebellopontine angle
It presents with hearing loss, facial nerve palsy (due to compression of the nearby facial nerve) and tinnitus
What are bilateral vestibular schwannomas associated with?
Neurofibromatosis type 2
What are cluster headaches?
- An attack of severe pain localised to the UNILATERAL orbital/supra-orbital and/or temporal areas.
- Known to be one of the most painful conditions that patients can have the misfortune to suffer
What is the pattern of headaches in cluster headaches?
Typically occur in clusters lasting several weeks, with the clusters themselves typically once a year
Can last between 15 minutes to 3 hours
What is the epidemiology of cluster headaches?
More common in men (3:1) and smokers
What can trigger a cluster headache?
Alcohol
What are the features of cluster headaches?
- Intense sharp, stabbing pain around one eye (once or twice a day, each 15mins-2 hours), patient is restless and agitated during the attack
- Redness, lacrimation and lid swelling
- Nasal stuffiness
- May have mitosis and ptosis
How long do clusters typically last in cluster headaches?
4-12 weeks
What are the investigations for cluster headaches?
Neuroimaging: 1st line is MRI gadolinium
May find underlying brain lesions even if the clinical symptoms are typical for cluster headache
What is the management for cluster headaches?
NICE recommend seeking specialist advice from a neurologist if a patient develops cluster headaches
1. Acute
2. Prophylaxis
What is the management for an acute cluster headache?
- 100% oxygen (80% response rate within 15 minutes)
- Subcutaneous triptan (75% response rate within 15 minutes)
What is the prophylaxis management for cluster headaches?
- Verapamil is the drug of choice
(there is also some evidence to support a tapering dose of prednisolone)
What diseases are part of the trigeminal autonomic cephalgia group?
- Cluster headaches
- Paroxysmal hemicrania
- Short-lived unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT)
What should happen to patients with a disease from the trigeminal autonomic cephalgia group?
Patients should be referred for specialist assessment as specific treatment may be required, e.g. paroxysmal hemicrania responds very well to indomethacin
What is encephalitis?
Inflammation of the brain parenchyma
What is the pathophysiology of encephalitis?
- HSV-1 is responsible for 95% of cases in adults
- Typically affects temporal and inferior frontal lobes
What are the features of encephalitis?
- Fever
- Headache
- Psychiatric symptoms (change in personality)
- Seizures
- Vomiting
- Focal features e.g. aphasia
(peripheral lesions (e.g. cold sores) have no relation to the presence of HSV encephalitis)
What are the signs of encephalitis on examination?
1.Reduced level of consciousness with deteriorating GCS
2. Seizures
3. Pyrexia
4. Signs of meningism: Neck stiffness, photophobia
5. Signs of raised ICP: hypertension, bradycardia, papilloedema.
6.Mini-mental examination may reveal cognitive or psychiatric disturbances
What are the investigations for encephalitis?
- Lumbar puncture: cerebrospinal fluid
a. Lymphocytosis
b. Elevated protein
c. PCR for HSV, VZV and enteroviruses - Neuroimaging:
a. medial temporal and inferior frontal changes (e.g. petechial haemorrhages)
b. normal in one-third of patients
c. MRI is better - EEG: lateralised periodic discharges at 2 Hz
What is the management of encephalitis?
IV aciclovir should be started in all cases of suspected encephalitis
What is Kernigs sign in meningism?
Positive when the thigh is flexed at the hip and knee at 90 degree angles, and subsequent extension in the knee is painful (leading to resistance)
Indicates the presence of meningitis or subarachnoid haemorrhage
What is epilepsy?
A common neurological condition characterised by recurrent seizures
Are there any associated diseases with epilepsy?
Most commonly occurs in isolation
Can be associated with:
1. Cerebral palsy - 30% have epilepsy
2. Tuberous sclerosis
3. Mitochondrial diseases
How are seizures in epilepsy classified?
3 key features:
1. Where seizures begin in the brain
2. Level of awareness during a seizure
3. Any other features of seizures
What are the two main types of epilepsy?
Focal seizures
Generalised seizures
What are focal seizures?
- Start in a specific area on one side of the brain
- Level of awareness can vary
- Can be further classified into motor (e.g. Jacksonian march) or non-motor (e.g. deja vu) or other such as aura
What are generalised seizures?
- These engage or involve networks on both sides of the brain at onset
- Consciousness is lost immediately (no level of awareness)
- Can be further subdivided into motor (e.g. tonic-clonic) and non-motor (e.g. absence)
- Specific types: tonic-clonic, tonic, clonic, typical absence and myoclonic (brief rapid muscle jerks)
What is a focal to bilateral seizure?
Where the seizure starts on one side of the brain in a specific area before spreading to both lobes
What are some of the signs and features of epilepsy?
- Seizure activity: level of awareness, motor vs non-motor
- Biting their tongue
- Incontinence of urine
- Post-ictal phase: drowsy and tired for around 15 minutes
What are the features of a seizure originating in the temporal lobe?
- May occur with or without impairment of consciousness
- An aura occurs in most patients (e.g. rising epigastric sensation, deja vu, less commonly hallucinations)
- Seizures typically last around 1 minute
- Automatisms are common (e.g. lip smacking, grabbing, plucking)
What are the features of a seizure originating in the frontal lobe?
- Head/leg movements
- Posturing
- Post-ictal weakness
- Jacksonian march
What are the features of a seizure originating in the parietal lobe?
Paraesthesia
What are the features of a seizure originating in the occipital lobe?
Floaters/ flashes
What are the investigations for epilepsy?
For any seizure: A to E approach, including blood glucose to exclude hypoglycaemia, think cardiac causes too
Following their first seizures, patients generally have both an EEG and imaging = MRI
What is the management of epilepsy?
- Most neurologists start anti-epileptics following a SECOND epileptic seizure
- Common medications include sodium valproate (not for females of reproductive age), Carbamazepine, Lamotrigine, Phenytoin
- Other considerations include:
a. DVLA
b. Other medications (enzyme inducers and inhibitors to need to check)
c. women wishing to get pregnant or on contraceptives (talk to specialist neurologist)
What are the DVLA rules for patients who have epilepsy?
Patients cannot drive for 6 months following a seizure
Must be fit free for 12 months before being able to drive
What are the common anti-epileptic drugs?
- Sodium valproate: used for generalised seizures in men, P450 inhibitor
- Carbamazepine: used second line for focal seizures, P450 induced, side effects include leucopenia and agranulocytosis, dizziness
*3. Lamotrigine: used for a variety of generalised and focal seizures with a limited side effect profile (other than Stevens-Johnson syndrome)
What is the acute management of seizures?
- Most seizures terminate spontaneously
- If they don’t after 5-10 minutes: appropriate to administer ‘rescue’ medication = benzodiazepines such as diazepam (intranasally or buccal midazolam)
- If a patient continues to fit despite such measures = status epilepticus = MEDICAL EMERGENCY
What is status epilepticus?
Either:
1. A single seizure lasting > 5 mins or
2. More than 2 seizures within a 5 minute period without the person turning normal between them
MEDICAL EMERGENCY
What is the priority in status epilepticus?
Termination of seizure activity, which if prolonged will lead to irreversible brain damage
What is the management of status epilepticus?
- ABC: airway adjunct, oxygen, check blood glucose
- First line medication = IV benzodiazepines e.g. diazepam or lorazepam - this can be repeated after 10-20 minutes
- If ongoing (or established) status, it is appropriate to start a second line agent e.g. phenytoin or phenobarbital infusion
- If no response (refractory status) within 45 minutes from onset = general anaesthesia (best way to achieve rapid control of seizure activity)
What are the complications of epilepsy?
- Fractures with tonic-clonic seizures
- Sudden death in epilepsy
- Side effects of AEDs e.g. neutropenia, osteoporosis with carbamazepine
What is an extradural haemorrhage?
A bleed between the dura mater and the inner surface of the skull
What is the difference between an extradural haemorrhage and a haematoma?
A haematoma is a collection of blood and a haemorrhage is an acute bleed (most commonly becomes a haematoma)
What is the aetiology of an extradural haematoma?
Almost always caused by trauma and most typically ‘low impact trauma’
E.g. a blow to the head or a fall
The affected artery = middle meningeal artery: thin skill at the pterion overlies this and is vulnerable to injury
Collection of blood is therefore in the temporal region
What are the features of an extradural haematoma?
- Patient initially loses, briefly regains and then loses consciousness again after a low-impact head injury
- As the haematoma expands: patient develops a fixed and dilated pupil due to the compression of the parasympathetic fibres of the third CN
What is the brief regain in consciousness in an extradural haemorrhage known as?
The lucid interval
Consciousness is lost again due to the expanding haematoma and brain hernia
As the haematoma expands the uncut of the temporal love herniates = compression of parasympathetic fibres of CN3
What is the investigation of choice for an extradural haematoma?
Non-contrast CT
Shows a biconvex (or lentiform), hyperdense collection around the surface of the brain
Looks like a lemon
Collection is limited by the suture lines of the skull
What is the management for an extradural haematoma?
- In patients with no neurological deficit: cautious clinical and radiological observation may be appropriate
- Definitive treatment: craniotomy and evacuation of the haematoma (if midline shift and brain stem herniate - needs early surgical intervention)
What is Guillain-Barre syndrome?
An immune-mediated demyelination of the peripheral nervous system often triggered by an infection (classically Campylobacter jejuni)
What is the infection commonly associated with Guillain-Barre syndrome?
Campylobacter jejuni
What is the pathophysiology of Guillain-Barre syndrome?
- An inflammatory process
- Cross-reaction of antibodies after a recent infection which reacts with self-antigen on myelin on neurons
- Correlation between anti-ganglioside antibody (e.g. anti-GM1) and clinical features, found in 25% of patients
What is Miller Fisher syndrome?
A variant of Guillain-Barre syndrome
Associated with:
1. Ophthalmoplegia
2. Areflexia
3. Ataxia
Eye muscles are typically affected first
Usually presents as a descending paralysis rather than ascending (opposite to Guillain-Barre)
What are the characteristic features of Guillain-Barre syndrome?
- Initially may experience back/leg pain
- Later develop progressive, symmetrical weakness of all the limbs
2a. Weakness is ASCENDING (legs are affected first)
2b. Reflexes are reduced or absent - Sensory symptoms tend to be mild (e.g. distal paraesthesia) with very few sensory signs
What are some of the other features of Guillain-Barre syndrome?
- Progressive, symmetrical ascending weakness of all the limbs
- May be a history of gastroenteritis
- Respiratory muscle weakness
- Cranial nerve involvement:
a. Diplopia
b. Bilateral facial nerve palsy
c. Oropharyngeal weakness - Autonomic involvement:
a. Urinary retention
b. Diarrhoea
What is a less common finding in Guillain-Barre syndrome?
Papilloedema
Thought to be secondary to reduced CSF resorption
What are the investigations of Guillain-Barre syndrome?
- Lumbar puncture:
Rise in protein with a normal WCC = (albuminocytologic dissociation) - Nerve conduction studies:
a. Decreased motor nerve velocity due to demyelination
b. Prolonged distal motor latency
c. Increased F wave latency
What is a severe sign of Guillain-Barre syndrome on examination?
Type 2 respiratory failure
Important to identify early e.g. CO2 retention flap, bounding pulse, drowsiness
Can be insidious and needs regular assessment
What is the management and prognosis of Guillain-Barre syndrome?
Medical management:
1. IVIG
2. Plasma exchange (plasmapheresis)
MDT approach: Physiotherapy, SALT, Occupational therapy
Prognosis:
Takes between 6-12 months for full recovery in strength, can take as long as three years
What is Horner’s syndrome?
A disorder characterised by:
1. Miosis (small pupil)
2. Ptosis (dropping of the upper eyelid)
3. Anhidrosis (loss of sweating on one side)
Plus enophthalmos = sunken eye
What is the aetiology of Horner’s syndrome?
Disruption of the sympathetic trunk supplying the eye
What are some of the causes of Horner’s syndrome?
- Carotid artery disscetion
- Tumour: in the neck or chest cavity e.g. Pancoast tumour in the upper part of the lung
- Lesion in the midbrain, brainstem, upper spinal cord or eye
- inflammation affecting the lymph nodes of the neck
- Surgery or trauma to the neck or spinal cord
What are the features of Horner’s syndrome?
Unilateral symptoms
1. Miosis
2. Ptosis
3. Anhidrosis
(plus enophthalmos = sunken eye)
How can congenital and acquired Horner’s syndrome be distinguished?
Congenital = present since birth
Heterochromia (difference in eye colour) is seen in congenital Horner’s
How can anhidrosis in Horner’s syndrome distinguish where the lesion is?
- Anhidrosis of the face, arm and trunk = central lesion (S)
a. Stroke
b. Syringomyelia
c. MS
d. Tumour
e. Encephalitis - Anhidrosis of the face = pre-ganglionic lesion (T)
a. Pancoast tumour
b. Thyroidectomy
c. Trauma
d. Cervical rib - No anhidrosis = post-ganglionic lesion (C)
a. Carotid artery dissection
b. Carotid aneurysm
c. Cavernous sinus thrombosis
d. Cluster headache
What are the investigations for Horner’s syndrome?
- Drops e.g. aproclonidine: will cause significant dilation of the healthy eye and little dilation of the affected eye if Horner syndrome is caused by a third-order neuron abnormality — a disruption somewhere in the neck or above
- Imaging: e.g. CXR for Pancoast tumour, MRI/ CT for tumour in brain/ neck, Carotid USS for dissection
- Bloods: inflammatory markers
What is the management for Horner’s syndrome?
Often resolves when the underlying cause is treated e.g. surgery, chemotherapy/ radiotherapy for tumours
What is Huntington’s disease?
An inherited autosomal dominant neurodegenerative condition, which is progressive and incurable
What is Huntington disease characterised by?
Progressive chorea and dementia
Typically commencing in middle age
What is the pathophysiology of Huntington’s disease?
- Autosomal dominant
- Trinucleotide repeat disorder: repeat expansion of CAG
- Results in degeneration of cholinergic and GABA-ergic neurons in the striatum of the basal ganglia
- Due to a defect in huntingtin gene on Chr 4
What is anticipation in the context of Huntington’s disease?
It is a trinucleotide repeat disorder
Phenomenon of anticipation where the disease presents at an earlier age in successive generations
What are the features of Huntington’s disease?
Typically develop after 35 years
1. Chorea (involuntary, jerky dyskinetic movements)
2. Personality changes (e.g. irritability, apathy, depression) and intellectual impairment
3. Dystonia (spasms)
4. Saccadic eye movements (quick simultaneous movement of both eyes)
5. May develop cognitive deficits a.k.a dementia
What are the investigations for Huntington’s disease?
- Genetic analysis: diagnostic if >39 CAG repeats in the HD gene
- Imaging:
a. Brain MRI or CT may show symmetrical atrophy of the striatum (particularly the caudate nuclei) and butterfly dilation of the lateral ventricles
b. not specific as it is seen in other conditions
What is the management for Huntington’s disease?
Incurable
Treatment for dystonia and depression .e.g. haloperidol
Occupational therapy have a large role
What is the prognosis of Huntington’s disease?
Typically results in death 20 years after the initial symptoms develop
What is Ramsay Hunt syndrome?
A syndrome caused by the reactivation of the varicella zoster virus in the geniculate ganglion of the seventh cranial nerve (facial nerve)
What are the features of Ramsay Hunt syndrome?
- Auricular pain (often the first feature)
- Facial nerve palsy
- Vesicular rash around the ear
- Other features include vertigo and tinnitus
What is the management of Ramsay Hunt syndrome?
Oral aciclovir and corticosteroids
What is hydrocephalus?
A condition in which there is an excessive volume of cerebrospinal (CSF) fluid within the ventricular system of the brain
Caused by an imbalance between CSF production and absorption
How can hydrocephalus be broadly divided?
Obstructive ‘non-communicating’ and non-obstructive ‘communicating’
What is obstructive hydrocephalus caused by?
- Due to a structural pathology blocking the flow of CSF
- Dilation of the ventricular system is seen superior to the site of obstruction
- Causes include tumours, acute haemorrhage e.g. SAH or intraventricular and developmental abnormalities e.g. aqueduct stenosis
What is non-obstructive hydrocephalus caused by?
- Imbalance of CSF production or absorption
- Either caused by an increased production of CSF e.g choroid plexus tumour (very rare)
- More commonly caused by a failure of reabsorption at the arachnoid granulations e.g. meningitis or post-haemorrhagic stroke
What is normal pressure hydrocephalus?
- A unique form of non-obstructive hydrocephalus
- Characterised by large ventricles but normal ICP
- Classic triad of symptoms:
a. Dementia
b. Incontinence
c. Disturbed gait
What are the features of hydrocephalus?
- Patients usually present with symptoms of raised ICP
- Headaches: typically worse in the morning, when lying down and during valsalva (forceful expiration against a closed airway)
- Nausea and vomiting
- Papilloedema
- Coma in severe cases
What are the investigations for hydrocephalus?
1st line: CT head: fast and shows adequate resolution of the brain and ventricles
2. MRI may be helpful for further detail especially if there is an underlying lesion
3. Lumbar puncture:
a. Both diagnostic and therapeutic in non-obstructive hydrocephalus
b. Allows sampling of CSF, measuring the opening pressure
c. Also allows drainage of CSF to reduce the pressure
When must you NOT carry out a lumbar puncture in hydrocephalus?
LP must not be used in obstructive hydrocephalus = the drainage of CSF will cause a difference in cranial and spinal pressures leading to brain herniation (coning)
What is the management of hydrocephalus?
- External ventricular drain: used in acute, severe hydrocephalus and is typically inserted into the right lateral ventricle and drains into a bag at the bedside
- Ventriculoperitoneal shunt: long-term CSF diversion technique that drains CSF from the ventricles to the peritoneum
- In obstructive hydrocephalus: may involve treating the obstructive pathology e.g tumour, SAH
What is the epidemiology of hydrocephalus?
Bimodal age distribution:
1. In the young = congenital malformations and tumours
2. in the elderly = tumours and strokes
What is idiopathic intracranial hypertension?
A condition classically seen in young, overweight females with features of headache, blurred vision and papilloedema
What are the risk factors for idiopathic intracranial hypertension?
- Obesity
- Female sex
- Pregnancy
- Drugs: COCP, steroids, tetracyclines, retinoids, lithium
What are the features of idiopathic intracranial hypertension?
- Headache
- Blurred vision
- Papilloedema
- Enlarged blind spot
- Sixth nerve palsy (abducens)
What is 6th nerve palsy?
The most common ocular motor paralysis to occur in isolation in adults
The eye cannot abduct (due to lack of innervation of the lateral rectus)
What is the management of idiopathic intracranial hypertension?
- Weight loss
- Diuretics e.g. acetazolamide
- Topiramate - added benefits of causing weight loss
- Repeated LP may be a temporary measure
- Surgery:
a) optic nerve sheath decompression and fenestration may be needed to prevent damage to the optic nerve
b) lumboperitoneal or ventriculoperitoneal shunt may also be performed to reduce ICP