Neurology Flashcards
What are first line treatments for neuropathic pain? (incl. drug class)
amitriptyline - TCA
duloxetine - SNRI
gabapentin - antiepileptic (blocks Ca2+ channels to inhibit release of glutamate from pain nerve endings)
pregabalin - antiepileptic (-II-)
(monotherapy!)
PAGD - don’t want to get PAGeD about neuropathic pain
What is neuropathic pain?
pain which arises following disruption or damage of the nervous system
what are some causes of neuropathic pain?
diabetic neuropathy
post-herpetic neuralgia
trigeminal neuralgia
prolapsed intervertebral disk
Defective downward gaze and vertical diplopia - which cranial nerve is affected?
CN IV
Between which layers is the bleed in a subdural haemorrhage?
damage to the bridging veins between the cortex and the venous sinuses
Name a diuretic that can cause gynaecomastia and explain how
Spironolactone (spironoLACTone)
It competitively inhibits the binding of dihydrotestosterone (DHT) to androgen receptors
-> leading to a decrease in testosterone levels and an increase in estrogen levels
-> This hormonal imbalance results in the development of breast tissue enlargement in men.
Characteristic presentation of clostridium botulinum infection
IVDU/eating contaminated (canned) food with descending paralysis, diplopia and bulbar palsy
Spreading of reflexes
- this is an abnormal sign that can be seen on neurological examination
- when you elicit a reflex, a different muscle twitches too
Sx of MND
Presentation:
- onset usually age 50-70
- asymmetric weakness in hands/feet
- onset tends to be focal, distal and asymmetrical; progresses in a segmental fashion from one limb to the other.
- initial presentation is highly variable
- atypical/non-specific symptoms at presentation: subtle vocal changes
Life-threatening sx as the condition progresses:
- respiratory impairment
- dysphagia
Age of onset of MND + gender
50-70
more common in males (2:1)
Other names for MND
Amyotrophic lateral sclerosis (ALS) is often used synonymously (although you could also say that ALS is a subtype of MND)
Lou Gehrig’s disease
what does ALS stand for?
amyotrophic lateral sclerosis
prognosis of MND
Most patients die within 3-5 years
30% have a chance of living longer
How is MND diagnosed?
MND is a clinical diagnosis -> hx and clinical examination showing UMN and LMN signs
there is constant disease progression
there may be an element of cognitive impairment
What is the split hand sign and what condition is it seen with?
wasting pattern of the hands in which the muscles of the thenar eminence atrophy due to degeneration of the lateral portion of the anterior horn of the spinal cord.
Muscles of the hypothenar eminence are spared.
-> associated with MND (relatively specific)
-> can also be a lesion of the ulnar nerve (exclude this first)
What form of dementia is associated with MND/ALS?
frontotemporal dementia
Ix in ?MND
- MRI brain and spinal cord to exclude other causes
- EMG supports the diagnosis (shows presence of denervation) - can also see EMG changes of the tongue
- nerve conduction studies are usually normal but can show a reduction in motor nerve conduction amplitudes)
Management of MND
- supportive (there is no cure)
- see in MND specialist clinic
- MDT: includes PT/OT, Psychology, SALT, neurologist - may need noninvasive respiratory support, symptom management (e.g. cramps, spasticity, pain), walking aids, feeding tubes etc.
- consider the carer(s)
Medicines:
- Rilouzole - glutamate receptor antagonist in the CNS, prolongs survival and slows functional decline by about 3 months (-> rilouzole rilly helps Lou Gehrig’s) - check liver enzymes
What is the first line treatment of ocular myasthenia gravis?
long acting ACh esterase inhibitor
e.g. pyridostigmine
What are Broca’s and Wernicke’s areas for? What happens in Broca’s and wernicke’s aphasia?
Broca’s: Producing speech
-> B’s aphasia: Cannot speak fluently, is very effortful and halting; understands speech and can read;
->classically caused by lesions affecting the frontal lobe (think: what you say makes up who you are -> frontal lobe)
Wernicke’s: Understanding & processing speech
-> W Aphasia: speaks, however the content is non-sensical. issues with reading and repeating what was said.
-> Associated with lesions in the posterior superior temporal gyrus
B= broken speech
W= what? struggles understanding
Pyridostigmine MoA and indications
long-acting ACh esterase inhibitor
Used in:
- myasthenia gravis
what is myasthenia gravis?
an autoimmune condition affecting the NMJ
most commonly with antibodies against the ACh R
(but can be other postsynaptic antibodies)
signs and symptoms of myasthenia gravis
- diplopia
- muscle weakness
- ptosis
- blurred vision
- sx worsening after repetition of movements / worse in evening
- difficulty standing from chair/brushing hair/climbing stairs.
- bulbar muscle involvement: difficulty chewing, swallowing, dyspnoea
- often eye muscle movement issues initially, then involvement of larger muscles.
What is a myasthenic crisis and how is it treated?
worsening of muscle weakness resulting in respiratory failure needing intubation and ventilation.
treated with plasmapharesis and IVIG
pathophys of myasthenia gravis
myoid cells in the thymus express AChR -> autoreactive targeting by T-cells -> production of AChR antibodies
How is Myasthenia gravis diagnosed?
Clinically you see:
- weakness (limb weakness is symmetrical)
- eye signs of MG (diplopia, ptosis, blurry vision)
- FATIGUABILITY
Can do the following ix to aid the diagnosis:
- antibody testing for anti-AChR (however a minority of patients can be seronegative)
- EMG
- tensilon test (after injection sx should improve; not used commonly anymore because of risk of cardiac arrythmias;)
- CT chest to screen for thymoma
how is Myasthenia gravis managed?
Medical:
- Pyridostigmine (long acting ACh esterase inhibitor)
- Immunosuppression (initially prednisolone, can also use azathioprine, cyclosporine, MMF)
Surgical:
- thymectomy if the patient has a thymoma
+ CT chest to screen for thymoma
What is classically associated with a pancoast tumour?
Horners syndrome
What is Bell’s palsy?
An idiopathic, unilateral, acute facial nerve (CNVII) paresis/paralysis.
(there are other (secondary) causes of a facial nerve palsy e.g. trauma, infections, brainstem stroke, tumours and metabolic d/o but these are then not called Bell’s.
Signs and symptoms of Bell’s palsy
- decreased or absent movement in the facial muscles
- hyperacusis
- altered taste
- dry eyes and mouth
- decreased lacrimation
- lagophthalmos (inability to close eyes completely)
- sensory disturbances: painful sensation around or behind the ear, impairment of taste in the anterior tongue, hyperacusis.
- can get bell’s phenomenon (eye sign)
Aetiology of Bell’s palsy
idiopathic
?links to HSV infection
Management of Bell’s palsy
- give prednisolone within 72h of onset of palsy (?25 mg BD for 10/7 or 6mg daily for 5/7 followed by 10mg/day for 5/7 more and total 10/7 -> pred increases the chance of complete recovery to 82%
- there is an ongoing debate about the addition of antivirals
- Eye care: advise to make sure eye is closed for sleep and prescribe artificial tears/lubricants; consider taping eye over night.
F/U
- follow up after 3 w
- if not improved after 3 weeks, refer urgently to ENT
- can refer to plastics in long-standing weakness (several months)
Prognosis of Bell’s palsy
- most people make a full recovery after 3-4 months.
- if untreated, around 15% people have permanent moderate to severe weakness.
Metoclopramide MoA
Dopamine antagonist with 5HT3A antagonist activity
-> antiemetic
Why does a CN III palsy cause ptosis?
Due to the impairment of the innervation of the levator palpaebrae superioris?
albumino-cytologic dissociation - what does this mean and what condition is it seen in?
CSF has high protein but normal WCC
seen in Guillian Barre syndrome
What is Ramsay Hunt Syndrome?
Herpes Zoster infection of the facial nerve (CN VII)
What is optic neuritis?
inflammation of the optic nerve
causes of optic neuritis
Most common cause is MS
Can also be due to Infection (TB, syphilis, lyme disease, viral infection)
Toxic: ethambutol/methanol poisoning
sx of optic neuritis
- blurry vision
- sudden vision loss
- colour blindness
- visual field defects (e.g. central scotoma)
- mild pain on eye movement (=retrobulbar pain)
ix findings for optic neuritis
- clinical examination: relative afferent pupillary defect
- neurological examination showing the signs listed above
- ophthalmoscopy: retrobulbar neuritis -> normal findings on ophthalmoscopy usually; papillitis: poorly defined papilla, hyperemia, haemorrhage at the border of the papilla.
- VEP (Visual evoked potential)
- MRI head
management of optic neuritis
steroids!
also manage MS if this is the cause
prognosis of optic neuritis
- visual improvement usually starts after 2/52
- visual acuity is usually good after 1 year
- frequent persistence of deficits in color vision and contrast sensitivity
Definition and aetiology of Wernicke’s
Definition:
An acute reversible presentation caused by thiamine deficiency. Patients present with at least one of 1. confusion, 2, ophthalmoplegia, 3. ataxic gait.
Aetiology:
Due to thiamine deficiency, most commonly in chronic heavy alcohol use.
Thiamine is needed for glucose metabolism. Deficiency causes symmetrical loss of brain function.
Signs, sx and ix in Wernicke’s
Signs/Symptoms:
- Confusion
- Ataxic gait (small steps, wide-based steps), +ve Romberg’s
- Oculomotor dysfunction (diplopia, nystagmus, conjugate gaze palsy
Examination:
- fluctuating mental state/confusion
- Ataxic gait (small steps, wide-based steps), +ve Romberg’
- Oculomotor dysfunction (diplopia, nystagmus, conjugate gaze palsy
- there may be signs of chronic liver disease
Investigations:
- clinical diagnosis!
- thiamine levels in the blood can be used in rare cases where clinical findings alone are insufficient for the diagnosis.
- tests to consider/rule out other diganoses (bloods, urine dip, head imaging)
Management of Wernicke’s
Give Thiamine!!
if the patient also needs glucose:
thiamine should be given before glucose or concurrently.
Do not give glucose before thiamine as this can worsen the symptoms (thiamine is needed for glucose metabolism)
Prognosis of Wernicke’s
Prognosis:
depends on how fast you give thiamine
partial recovery within the day followed by full recovery within weeks is possible if thiamine is started rapidly.
If untreated:
20% mortality rate if untreated
other survivors develop psychosis and Wernicke-korsakoff syndrome which is irreversible.