Neurology Flashcards
Explain the concept of cerebral dominance
Right handed people + 70% of left handed people have language function on the left, so left-sided disorders typically cause communication disorders like dysphasia/agraphia/alexia
Corticospinal tract
The voluntary motor pathway to control LMNs (corticobulbar tracts for H+N muscles)
- In the medulla they form pyramids as they cross and run down the lateral CST to synapse onto a LMN that supplies a muscle
- 15% run ipsilaterally then cross at the spinal level of their LMN
- Also give off fibres to motor CN nuclei
- UMN for the UL is in the lateral cortex, UMN for the LL is in the medial cortex
Corticonuclear projections
UMN projections to the motor cranial nerves - all receive b/l innervation, except the facial n nucleus which has upper half with b/l innervation but lower half only the contralateral projections. This is why UMN palsies may spare forehead but LMN ones do not
Extrapyramidal motor systems
- Basal ganglia: allow the fast fluid movements generated by the CST
- Cerebellum: coordinate smooth + learned movements inc for balance + posture
Upper motor neurones
Found entirely within the motor cortex of the CNS and synapse onto LMNs, on which they usually have an inhibitory effect
UMN disorders
- Hemiparesis: one sided weakness, usually a brain lesion tho could also be a SC lesion
- Paraparesis: weakness of both LL, usually a cord lesion but could be b/l medial brain issue
- Tetra/quadraparesis: all 4 limbs
Lower motor neurones
Mostly found in the ventral horns + in the motor nuclei of CNs
LMN signs
Start in a single limb and progress - weakness as not stimulated, wasting (loss of trophic factor), hyporeflexia at level of damage (reflex arc broken), hypotonia, fasciculations (ectopic AChR), fibrillations (minute contractions on EMG), eventually UMN signs
LMN disorders
CN nuclei problem Anterior horn cell - MND Spiral root radiculopathy e.g. disc protrusion Peripheral nerve entrapment/trauma Polyneuropathy
UMN signs
- Weakness-flaccid then spastic
- Hemiplegia, hemiparesis (plegia technically means total paralysis but often used for severe weakness)
- Hypertonia: UL flexed, LL extended
- Hyperreflexia - less inhibition of reflex arc
- Extensor plantar response
- Clonus
- Pronator drift
- No wasting, but may get this from disuse
Somatosensory system
Carries conscious sensation from body walls: cell body in DRG/trigeminal ganglion –> SC –> secondary neurone which decussates and goes to thalamus –> 3rd neurone –> sensory cortex
Dorsal column medial lemniscus system
Detects vibration, proprioception, light touch + 2 point discrimination
*Primary afferent travels up DC to medulla - synapse in GF (lower body, medial) or CF (upper body, lateral) –> 2nd degree decussate in medulla –> synapses with 3rd degree in thalamus –> projects to sensory cortex
Spinothalamic tracts
Detect pain, temperature + crude touch. In anterior SC
- 1st degree synapse in dorsal horn of cord, 2nd degree decussate in cord at level of entry –> pass in STT to thalamus —> synapse with 3rd neurone.
- As ascend cord axons are added on medially to the STT (cf DCML)
Where is the sensory cortex?
In the parietal lobe
What are the potential locations for neurological pathology?
Cerebral cortex White matter Basal ganglia Cerebellum Brainstem Cranial nerves Spinal cord Spinal roots Peripheral nerves NMJ Muscle
Outline the approach to localisation of neuro sx
- What is the minimal amount of neuroanatomy that must be damaged to produce the CF? e.g. in monocular blindness the lesion must be ipsilateral and somewhere between the cornea and optic chiasm; aphasia must be a lesion of the dominant hemisphere (which is usually left)
- If the lesion is here, does it explain these findings? If not either you are wrong or disease process is multifocal
- If the lesion is here, what else should be present?
Typical CF of problem in cerebral hemispehre
Hemiplegia (UMN) and/or hemisensory loss, aphasia, neglect, hemianopia, dementia, seizure
Typical CF of problem in meninges
Headache, altered consciousness, CN deficits
Typical CF of problem in basal ganglia
Chorea, athetosis, dystonia, tremor, rigidity
Typical CF of problem in cerebellum
DANISH
Typical CF of problem in spinal cord (myelopathy)
LMN weakness at level of lesion
UMN below level of lesion
Sensory level
Neurogenic bladder
Typical CF of problem in nerve roots (radiculopathy)
Radicular pain, motor/sensory/reflex loss in a specific myotomal/dermatomal distribution
Typical CF of problem in plexuses
Mixed nerve + root distribution of loss
Typical CF of problem in peripheral nerves (neuropathy)
Pain, motor, sensory + reflex loss in a specific nerve distribution; or distal symmetrical sensory loss/weakness
Typical CF of problem in neuromuscular junction
Fatiguable weakness, no sensory sx
Typical CF of problem in muscle (myopathy)
Proximal weakness, no sensory sx
What are the indications for lumbar puncture?
Suspected SAH, meningitis, encephalitis, certain immunological eg MS/GBS, therapeutic removal of CSF, measurement of CSF pressure, intrathecal injection
Contraindications for lumbar puncture
Focal neurology, RICP, suspicion of a mass lesion in CNS (as reducing pressure by removing CSF could cause coning), local infection near LP site, congenital lesions like myelomeningocele, plt<40, anticoagulation issues, if unconscious/have papilloedema need CT first
How is a lumbar puncture performed?
Lie in left lateral position
Do between L3-4 or L4-5 vertebrae (L4 usually between the iliac crests)
Sterile
Inject lidocaine into dermis, push through skin, when feel penetrated dura withdraw + allow a few drops of CSF to escape
Record pressure, collect specimens, also take blood glucose, record appearance of CSF
Lie flat to avoid headaches
What are the basic principles of interpreting brain imaging?
- Midline shift
- Obvious hyperdense areas (bleed on CT) or hypodense (infarct on CT)
- Attenuation
- Burr holes
- GM/WM distinction
- Gyri + sulci
- Calcific changes
- Small vessel disease (often at ventricle edges)
- MCA distribution
What types of imaging are used in neurology?
- Spinal XR
- CT brain
- CT angiography
- MRI brain/spine
- Doppler US-carotid stenosis. Less reproducible but safe+low cost
- Catheter angiography-more invasive
- Functional MRI-research tool
- FDG-PET-for occult neoplasms or large vessel vasculitis
- DAT-Parkinsonian disorders when diagnosis uncertain
What neurophysiological ix are used in neurology?
- EEG: scalp electrodes record brain electrical activity, used to characterise epilepsy syndromes
- EMG + nerve conduction studies: skilled ix of nerve function for peripheral nerve/anterior horn/NMJ disease
- Cerebral evoked potentials
Describe the knee spinal reflex arc
Tapping on patellar tendon - stretch receptors in quad activated - impulses in 1st order sensory neurone go to LMN (L3+L4) - contract quad
What are negative + positive sx?
Positive: exaggeration of a physiological phenomenon
Negative: loss of function so a destructive lesion causing failure of impulse conduction
Typical CF of problem in brainstem
u/l CN deficits, impaired consciousness, crossed/bilateral motor/sensory deficits
What is a ‘sensory level’?
The last level where the sensation is normal is the level of the lesion in a SC problem
Hemiplegic gait
Asymmetrical as one limb spastic, toes on affected side may drag on floor + leg circumducts during swing face
Causes: UMN lesions so a u/l brain lesion on contralateral side (stroke, tumour, demyelination, SOL) or hemisection of SC (Brown-Sequard)
Diplegic gait (scissoring)
b/l but similar to hemiplegic gait, legs drawn together due to spasticity
Causes: SC lesion (usually also affects sensation, e.g. prolapsed disc, tumour, transverse myelitis), b/l b/l brain lesion (e.g. MS, b/l infarct, midline tumour), or MND (in which LMN signs would occur)
Parkinsonian gait (festinating)
Short steps, shuffling, reduced arm swing, difficulty with stopping/starting/turning
Causes: idiopathic Parkinson’s disease (most features of gait + the classic triad), parkinsonian disorders (some features of gait, not all of triad, sometimes other features)
Ataxic gait
- Cerebellar lesions: ipsilateral (stroke or SOL), bilateral (MS, alcoholism, B12 def, some drugs, genetic, paraneoplastic, multi-systems atrophy
- Sensory neuropathy: appears ataxic due to impaired sensation, no other cerebellar signs
- Vestibular: a/w N+V and vertigo
Neuropathic (high steppage) gait
Motor weakness of nerves supplying tibialis anterior (L4-S1 root), foot drop + toes drag, to prevent drag knee + hip flex excessively making high stepping gait
Causes: isolated common peroneal nerve palsy (trauma/compression e.g. #HoF, inversion preserved), L5 radiculopathy, generalised polyneuropathy
Sensory (stomping) gait
Peripheral sensory nerve impairment meaning pt can’t sense foot location
Usually dorsal column issue like B12 def/tabes dorsalis, or peripheral nerve diseases
Myopathic (Trendelenberg) gait
Weak hip abductors so pelvis tilts down, body compensates by flexing torso laterally + circumducting leg. ‘Waddling’
Causes:
- Systemic: hyper/hypothyroidism, Cushing’s syndrome, acromegaly, polymyalgia rheumatica, polymyositis
- Muscular dystrophies
Choreiform gait (hyperkinetic)
Normal gait with involuntary choreic movements e.g. oro-facial dyskinesia, or choreic movements of limbs (dance like semi-purposeful movements)
Causes: basal ganglia disorders e.g. Huntington’s disease, Sydenham’s chorea, Wilson’s disease, dopaminergic meds
Antalgic gait
Shortened length of time in stance phase on affected leg due to pain - any cause of pain e.g. OA, #, inflammation, nerve entrapment
What is a tremor?
Regular sinusoidal oscillation of limbs/head/trunk
What are the causes of tremor?
- Postural - physiological, everyone has when outstretch hands, pronounced with anxiety/caffeine/hyperthyroidism/drugs. Higher amplitude than benign essential tremor
- Essential - common, often inherited, b/l fast low-amplitude, mostly of the upper limb, postural e.g. when holding something, can be of vocal cords causing vibrating voice, anxiety worsens it so small amounts of beta blocker may help
- Intention - exacerbated by action with past-pointing + dysdiadochokinesia
- Rest - worse at rest, a/w Parkinsonism, often pill-rolling
- Dystonic - usually u/l, worse with certain tasks
- Holmes - at rest/action, lesion in red nucleus
- Sympathomimetics e.g. salbutamol - make all tremors worse
What is chorea?
Excessive irregular movements that flit from one body part to another
What are the causes of chorea?
- Systemic - thyrotoxicosis, SLE, APS, polycythaemia vera
- Genetic: HD, benign hereditary chorea
- Structural or vascular issues of the basal ganglia
- Drugs - levodopa, COCP
- Post-infection: Sydenham’s chorea, after strep/acute rheumatic fever
- Pregnancy
Huntington’s disease
Presents in middle life with ‘fidgeting’ chorea, then progressive psych + cognitive sx
AD inheritance of a CAG repeat expansion in a protein, demonstrates anticipation (successive generations tend to have earlier onset + more severe disease)
M: no DMD work, risperidone/sulpiride for the chorea, progressive neurodegenetation, dementia, death after 10-20y
Hemiballismus
This is violent swinging movements of one side
- Usually due to infarct or haemorrhage of the contralateral sub thalamic nucles
- Can also occur acutely after hyperosmolar hyperglycaemia cos of the osmotic shifts
What is myoclonus?
Brief shock like jerks
Causes of myoclonus
- Primary: physiological when going to sleep/waking, myoclonic dystonia, myoclonic jerks in epilepsy
- Secondary to metabolic disorders like asterixis, dementia or encephalitis
What are tics?
Brief stereotyped movements or vocalisations, often affecting the face + neck
They can be transiently suppressed, then a build of anxiety + overflow after release
Causes of tics
- Simple transient tics common in children like blinking, sniffing
- Adult onset is rare and usually a secondary cause
- Tourette syndrome: multiple motor tics + at least one vocal tic, a/w behavioural problems + OCD, sometimes get explosive grunting of obscenities (coprolalia) or coping what other people say (echolalia)
What are dystonias?
Twisting movements + abnormal postures due to muscle spasm
Treated with botulinum toxin injections
Causes of dystonia
- Primary - dystonia is the main CF, usually a genetic cause. E.g. torticollis (wry neck, neck muscle spasms), blepharospasm (forced blinking), task-specific (e.g. writer’s cramp-other hand functions normally)
- Secondary to brain injury, cerebral palsy or drugs (metoclopramide, antipsychotics)
- Hereditary-degenerative disorders
- Paroxysmal dystonia - rare
What are neuroleptic movement disorders?
Disorders caused by certain antiemetics + antipsychotics
May cause akathisia (restless), Parkinsonism (dopamine blockade), acute dystonic reactions (e.g. oculogyric crisis [sustained upward gaze, often develops acutely after 1 dose]), tar dive dyskinesia (often after years of medS)
Neurological causes of urinary incontinence
- Cortex: post-central cause loss of bladder sensation, pre-central cause difficulty initiating micturition, frontal lesions can cause socially inappropriate micturition
- Cord: b/l UMN lesions cause frequency + incontinence so bladder sensitive to small changes in pressure
- LMN: sacral lesions cause flaccid atonic bladder that overflows
Causes of dizziness
- Peripheral causes of vertigo (common)
- Syncope
- Unsteadiness e.g. cerebellar disorders
- Central causes of vertigo: rare. E.g. vestibular nuclei infarcts, demyelination in the brainstem, posterior fossa mass lesions, migrainous vertigo, CPA mass lesions compression vestibular nerve, drugs .e.g anticonvulsants
Presentation of optic nerve lesions
- Central scotoma + u/l vision loss
- Impaired colour vision
- Full lesion-u/l blindness + loss of pupillary reflex
- Optic atrophy (late)
What can cause an optic nerve problem?
- Inflammatory optic neuritis
- Optic nerve trauma or compression from glioma or aneurysm
- Toxicity from alcohol, ethambutol, quinine
- Ischaemia e.g. GCA
- Hereditary
- Nutritional deficiency e.g. B1 or B12
- Infection e.g. orbital cellulitis, syphilis, TB
- Neurodegenerative
- Papilloedema
What are the causes of optic disc swelling?
- RICP (papilloedema)
- IIH
- Hydrocephalus
- Optic neuritis (papilllitis)
- Ischaemia e.g. GCA
- Toxicity e.g. methanol
- Venous occlusion or venous sinus thrombosis
- Central retinal vein thrombosis
- Orbital mass lesions
- Malignant HTN
- SLE
- Hypercapnia
- Disc infiltration e.g. leukaemia
How does optic disc swelling present?
- Pink disc
- Blurring of disc margin
- Loss of spontaneous retinal vein pulsation
- Obliteration of the cup
- Dilated vessels
- Small haemorrhages
- Papilloedema (when RICP is the cause) doesn’t produce visual sx except momentary visual obscurations w changes in posture
Optic neuritis
Subacute VL (not permanent), mild fogging of central vision, colour desaturation; rare to have complete blindness, disc looks normal unless inflammation at nerve head, common to get pain/discomfort esp on movement but shouldn’t be severe
Develops over a few days and recovers over 2w
Commonest cause is MS but can be cos of other inflammation
Anterior ischaemic optic neuropathy
Occlusion/hypoperfusion of posterior ciliary arteries –> infarction of optic nerve head
Sudden/stuttering visual loss + disc swelling then atrophy
Higher risk if small hypermetropic disc
How may a lesion at the optic chiasm present and what are the causes?
Bitemporal hemianopia or quadrantonopia
Causes: pituitary tumour, meningioma or craniopharyngioma
How do you differentiate a pre-chiasmal lesion from a post-chiasmal lesion?
Monocular lesions - pre-chiasmal
Homonymous lesions - post-chasmal (involve the same part of the VF in both eyes)
How do optic tract + radiation lesions present?
- Optic tract: homonymous hemianopia
* Optic radiation: homonymous quadrantonopia
How do lesions in the occipital cortex present?
- u/l infarct - homonymous hemianopia, macular cortex may be spared
- cortical blindness - widespread b/l damage by infarct/trauma/coning, pt characteristically lacks insight into this, the rest of the vision pathway is fine but they cannot interpret image
Abnormalities of lateral conjugate gaze?
Destructive lesion on one side means eyes driven by the opposite pathway which is intact
e.g. in acute cerebral lesion contralateral hemiparesis but the eyes look to the normal side (except brainstem lesion where eyes look to abnormal side)
Internuclear ophthalmoplegia
Damage to the ipsilateral MLF
- side of lesion causes impaired adduction on that side, a/w nystagmus of the other eye
- b/l INO is almost pathognomonic of MS
- INO may also be due to vascular disease
Nystagmus
Rhythmic oscillation of eye movement indicating disease in the retina/cerebellum/vestibular systems
- Jerk nystagmus: fast/slow oscillation, due to vestibular/CN VIII/brainstem/cerebellar issue
- Pendular nystagmus: usually vertical + in all directions of gaze, usually an eye cause e.g. severe visual impairment
Oculomotor nerve lesions
Supplies to SR, IR, MR, IO + LPS, plus carries PNS fibres for pupil constriction
Signs: u/l ptosis, down + out deviation, fixed dilated pupil. But they don’t c/o diplopia because ptsosi covers the eye. If pupil is spared it indicates an internal cause like diabetes
Causes: posterior communicating artery aneurysm, infarct of CN III in DM/atheroma, coning of temporal lobe, midbrain infarct or tumour
Trochlear nerve lesions
Supply SO, causes torsional diplopia when look down, head tilts away from that side, eye looking ‘up and out’. Usual cause is head injury
Abducens nerve lesions
Horizontal diplopia, LR palsy (cannot fully abduct), may have esotropia
Long intracranial course so can be damaged in brainstem by MS/infarct, compression in RICP, tumour infiltration, microvascular ischaemia in DM
Complete external ophthalmoplegia
Immobile eye as CN 3, 4 and 6 are all paralysed. Causes:
- Orbit e.g. metastasis
- Cavernous sinus e.g. thrombosis, meningioma
- Wernicke’s encephalopathy
- Myasthenia gravis
Optic atrophy
This is disc pallor due to loss of axons, glial proliferation + reduced vascularity
Can happen after any form of optic neuropathy
What is the difference between RAPD + APD?
Afferent pupillary defect: complete optic nerve lesion causes dilated pupil + APD so the direct + consensual responses for the affected eye are absent
RAPD: incomplete damage to one optic nerve relative to the other, so whilst the reflexes are there they differ in strength to the other eye
What’s the difference between dysphasia and dysarthria?
- Dysphasia - due to a problem in the dominant hemisphere, disorder of language
- Dysarthria - motor speech disorder (not comprehension/language/expression) causing slurred speech
What might a lesion in Broca’s area lead to?
Expressive dysphasia (frontal lobe) - patient knows what they want to say (comprehension is fine) but they can’t find the correct words (non-fluent speech), language becomes reduced to a few disjointed words. V frustrating for pt. Can repeat words better than spontaneous speech
What might a lesion in Wernicke’s area lead to?
Receptive dysphasia (temporoparietal region) - fluent speech with impaired comprehension so doesn’t make sense, pt lacks insight
Nominal vs global aphasia
Nominal/anomic: difficulty naming objects. Is an early feature
Global/central aphasia: loss of language production + understanding, inc reading + writing
What are bulbar symptoms?
Lesions in any of the articulation/phonation/swallowing pathways causing dysarthria, dysphonia + dysphagia; sometimes non-neurological local things like VC lesions
Lesions may be in motor cortex, brainstem, CN nuclei (corticobulbar fibres received from both sides), cerebellum, basal ganglia or NMJ
Causes of dysarthria
- UMN lesions: usually b/l because b/l innervation to the muscles. E.g. MS, MND, progressive supranuclear palsy. Slow indistinct strained speech
- LMN lesions: damage to CN VII/X/XII or their nuclei. b/l like GBS, MND. Slurred indistinct speech, nasal quality
- Basal ganglia lesions: Parkinson’s disease (low volume, monotonous, trails off), chorea (loud + harsh + variable), athetosis (loud + slow)
- Cerebellar lesions: slurred slow speech as impaired coordination (ataxia)
- Myopathies: weakness of muscles
- NMJ: fatiguability
- Oropharyngeal lesions: multiple ulcers, oral candidiasis, quinsy, dental abscess, loose dentures
Neurological causes of dysphagia
- B/l cerebral hemisphere vascular/trauma issues
- Brainstem - MS, vascular, tumours
- MND - from bulbar muscle palsy
- NMJ - MG
- Muscle - poliomyositis
- Pharynx + oesophagus pathology
Neuro cause - difficulty swallowing liquids then solids. Corticobulbar fibres so often occurs with dysarthria
Causes of dysphonia (altered volume/quality)
- Medullary lesions involving nucleus ambiguous (where CN X nucleus is) - infarct, tumour, demyelination
- RLN palsy - thyroid surgery, bronchial carcinoma, aortic aneurysm
- Vocal cord lesion - polyps, tumour
- Functional - psychogenic aphonia
What may cause memory problems?
Damage to medial structures of temporal lobes + brainstem connections e.g. hippocampi; amnesia due to b/l lesions
Causes: dementia, amnestic mild cognitive impairment, thiamine deficiency, severe head injury, anoxic brain damage, b/l thalamic stroke, SAH, diffuse small vessel disease, b/l tumours, TL epilepsy, post-hypoglycaemia, dissociative, transient global amnesia, transient epileptic amnesia, post-traumatic amnesia
Where does head pain originate from?
Pain receptors in base of brain arteries + veins, meninges, extra cranial vessels, scalp/neck/face muscles, paranasal sinuses, eyes + teeth
Brain parenchyma mostly has no pain receptors
What is the pathology of neuropathic pain syndromes?
Damage/dysfunction of the pain/sensory pathways e.g. peripheral nerve damage, radiculopathy, post-stroke pain, post-herpetic neuralgia
STT involved in pain localisation + spinoreticular tract in emotional component, project to thalamus to sensory cortex + limbic system
Gate theory - transmission of afferent pain impulses is gated in SC dorsal horn synapses + brainstem
Allodynia - normal sensory inputs can produce abnormal response due to central + peripheral sensitisation (increased excitability of nociceptors)
What are the causes of neuropathic pain syndromes?
- Peripheral nerve injury: peripheral neuropathy, nerve compression e.g. CTS/meralgia paresthetica, post-herpetic neuralgia, nerve trauma/section, trigeminal neuralgia
- Nerve root/plexus: radiculopathy from disc prolapse, plexopathy (inflammation, infiltrative e.g. breast cancer)
- CNS: MS, post-stroke pain, SC lesions, PD
How would you go about managing chronic pain?
- MDT pain clinics
- Diagnosis is important
- Psychological: CBT to control response, ADs can help
- Co-analgesics: primary use is not for pain but can help alone/as an adjunct. E.g. amitriptyline, duloxetine, anticonvulsants like carbamazepine/gabapentin, CCBs, muscle relaxants e.g. baclofen, topical capsaicin, cannabinoids, botulinum toxin
- Stimulation for gating effects - acupuncture, ice, heat, US, massage, TENS
- Nerve blocks e.g. LA
Trigeminal neuralgia
- Typical 50-60s, HTN
- Compression of CN V near pons by a vascular loop, MS or a CPA tumour
- CF: sudden onset knife/electric type pain for seconds in the CN V distribution, usually u/l, may have a trigger like washing/cold wind/chewing, no signs of CN V dysfunction o/e
- B/L sx means brainstem pathology e.g. MS
- M: carbamazepine 1st line to reduce severity, can try lamotrigine/gabapentin, some surgical options may be tried e.g. selective ablation. Usually spontaneously remits then recurs
How may sensory nerve disturbances present?
- Peripheral n lesions: within distribution of a nerve, section causes LoS and entrapment causes numb/pain/tingling
- Neuralgia: pain in distribution of nerve e.g. trigeminal or post-herpetic
- Root pain: pain in the myotome + tingling discomfort in the dermatome, worse on stretching e.g. SLR in disc prolapse/raised pressure like coughing
- Posterior cord lesions: all DCML diminished below lesion, tingling sensations
- Cervical cord lesion - Lhermitte’s pnenomenon
- STT lesion - c/l loss of pain + temp with a clear sensory level (in compressive lesions the lower roots are damaged first so the sensory level can ascend as deeper fibres become involved)
- Cord compression - progressive spastic paresis with sensory loss below lesion, often sphincter disturbance + root pain @ level of compression
- Thalamic lesions - deep seated pain in paretic limbs, movement disorders
- Parietal cortex lesions - sensory loss, neglect, apraxia, pain is NOT a feature
Causes of acute spinal cord compression
- Metastatic cord compression causing vertebral destruction - thyroid, lung, breast, renal, prostate, myeloma, NHL
- Trauma - vertebral #, facet joint dislocation
- Infection - acute or chronic, epidural abscess from osteomyelitis, TB (destroys VBs + local infection)
- Disc prolapse - rare as would usually cause cauda equina (inferior to SC, as lumbar herniations are the more likely location rather than further up)
- Narrowed canal e.g. RA, ankylosing spondylitis, osteophytes
- Chronic degenerative disc prolapse e.g. cervical or thoracic disc potrusion
- Extramedullary e.g. meningioma or intramedullary e.g. glioma tumours
- Epidural haematoma: rare comp of anticoagulants/bleeding disorders
CF of acute cord compression
UMN!
- Impaired sensation + proprioception at dermatomal level below lesion
- Pain esp on straining
- B/l or u/l weakness
- UMN signs (cf LMN signs in peripheral compression of nerve or cauda equina)
- Reflex may be absent at level of lesion due to compression of the LMN in the ventral horn
- Over time lesions at T12 or above cause bladder spasticity and below cause flaccidity
- Autonomic involvement - late. Incontinence or constipation or retention
- Evidence of cause e.g. WL
Management of acute cord compression
- MRI within 24h if suspect cord compression, within 7d if features of spinal mets but no compression yet
- High dose corticosteroids with gastro protection with PPI
- Neuro/oncology referral - decompression is definitive management if suitable, if cancer may have CT and/or RT if sensitive
- If still mobile at presentation majority remain so but if cannot walk at presentation only 1/3 will walk again
Brown-Sequard syndrome
‘Hemisection of cord’ tho usually not truly this
- Contralateral damage to STT - loss of pain + temp
- Ipsilateral CST damage - weakness on same side of lesion below the level
- Ipsilateral loss of DCML (proprioception + vibration)
What are the different types of spinal cord lesion according to symptoms?
- Motor: MND (UMN+LMN), poliomyelitis (anterior horn cells-LMN signs)
- Sensory: neurosyphilis tabes dorsalis (affects DCML)
- Combined motor + sensory:
- Brown-Sequard
- Subacute combined degeneration of cord
- Friedrich’s ataxia: same as SACD plus cerebellar ataxia
- Anterior spinal artery occlusion: b/l spastic paresis + loss of STT
- Syringomyelia
- MS: asymmetrical, varying tracts involved
How would you assess brainstem function?
- Pupils - CN III compression (1 pupil fixed dilated to light), metabolic comas (b/l mid-point reactive pupils ie normal), opiates (b/l pinpoint light-fixed), brain death (b/l light-fixed dilated)
- Eye movements + position: disconjugate (1 up 1 down=brainstem lesion), conjugate (deviate towards lesion of the frontal lobe and away from the lesion in the brainstem), vestibular-ocular reflex (passive head turning eyes also move [Doll’s eye reflex], absent in brainstem death), windscreen wiper eyes (in light coma)
- Brainstem reflexes - corneal, gag/cough, respiratory drive
- Lateralising signs - any asymmetrical response
Define coma
A state of unrousable unresponsive, GCS of 8 or lower
- Vegetative state: usually extensive cortical damage but brainstem intact so don’t need ventilating, pt has sleep/wake cycles but no response to stimuli except reflexes, permanent if no recovery after 6m/12m if trauma is the cause
- Minimally conscious state: fluctuating limited awareness, inconsistent but reproducible responses e.g. crying irt emotional stimuli
- Brainstem death
What may cause coma?
- Brainstem lesions: bleed, infection, demyelination, neoplasm, Wernicke-Korsakoff
- Brainstem compression: tumour, supratentorial mass lesion, bleed
- Diffuse brain dysfunction: severe metabolic/toxic disorders that depress the cortex+RAS like drug OD/CO poisoning/low or high glucose
- Massive cortical damage e.g. meningitis, HIE post-cardiac arrest, diffuse axonal injury from rapid accel/decel (causes multiple haemorrhages + diffuse axon damage in WM)
Coma look-alikes
Psychogenic coma, locked in syndrome
List the causes of blackouts and ‘funny’s turns’
- Epilepsy
- Syncope
- Non-epileptic attacks (pseudo seizures). May look tonic-clonic, no rise in serum prolactin, pelvic thrusting, cry after seizure, gradual onset
- Panic attacks + hyperventilation: sudden SNS activation, can lead to respiratory alkalosis. CF include dizzy, CP, feeling of choking/SOB, tingling in face+extremities, palps, feeling of impending doom
- Hypoglycaemia: confusion, LoC, sometimes convulse/dysphasia/hemiparesis, warning sx beforehand
- Drop attacks: usually women >60y due to sudden change in LL tone causing falling, no LoC
- Hydrocephalic attacks
- Basilar migraine or familial hemiplegic migraine
- Severe vertigo - can cause prostration
- Sleep disorders
- TIAs - almost never cause a LoC
What are the types of syncope?
- Neurocardiogenic/vasovagal: sudden reflex bradycardia with peripheral + splanchnic vasodilation. Triggers, brief prodome, pt usually still during blackout or some twitching/jerking, pale, may lose continence, no post-ictal state just fatigue, recover over seconds
- Cardiac (Stokes-Adams attacks): arrhythmia or left ventricular outflow obstruction, without warning or on exercise
- Micturition syncope
- Cough syncope - venous return to heart obstructed by severe coughing/laughter
- Postural hypotension
- Carotid sinus syncope - vagal response to pressure over carotid sinus baroreceptors e.g. tight collar
- Convulsive syncope: secondary anoxic seizure after syncope (like if collapse in a propped up position)
Name some common sleep disorders
- Insomnia
- Myoclonic jerks when fall asleep/wake - normal
- Narcolepsy - abnormal neurotransmitter causing excessive daytime sleepiness, inappropriately sleeping, cataplexy (sudden loss of muscle tone with intact awareness), dream-like hallucinations, sleep paralysis
- Parasomnias - disruptive motor/verbal behaviours during sleep inc sleepwalking + night terrors
- Restless leg syndrome - wanting to move legs with throbbing/pulling, usually relieved by stretch, idiopathic but can be triggered by drugs/pregnancy/uraemia/Parkinsons disease
What is Hoover’s sign?
Place hand under the asymptomatic limb and ask them to move the weak one - if there is an organic cause, examiner will feel the normal leg pushing downwards as pt attempts to lift weak leg. If this doesn’t happen it indicates that the weakness is functional
Causes of infantile hydrocephalus
- Arnold-Chiari malformation: cerebellar tonsils descend into cervical canal. A/w spina bifida + syringomyelia
- Stenosis of aqueduct of Sylvius: congenital/acquired from meningitis
- Dandy-Walker syndrome: cerebellar hypoplasia + obstruction of 4th ventricle outflow
Tends to cause increasing head circumference (as sutures unfused), bulging fontanelles, impaired upward gaze (‘sunsetting’, due to pressure on tectal plate), dilated scalp veins, bradycardias, seizures, coma
Causes of adult hydrocephalus
- Stable childhood hydrocephalus suddenly worsening
- Posterior fossa/brainstem tumour
- Obstructed resorption from SAH/head injury/meningitis
- 3rd ventricle colloid cyst
- Choroid plexus papilloma - rare, secrete CSF
What is normal pressure hydrocephalus?
Triad of gait apraxia + dementia + urinary incontinence
Pressure may actually be raised but is low-grade. Trial prolonged CSF drainage and then VP shunt sometimes (comps of shunt are seizure, infection + ICH but only in 10%)
Subarachnoid haemorrhage
- Causes: traumatic; spontaneous –> berry aneurysms in CoW (commonest spontaneous, a/w adult PKD, EDS + coarctation of aorta), AV malformation, bleeding disorders, acute meningitis, arteritis like SLE, pituitary apoplexy, mycotic aneurysms, peremesencephalic (idiopathic venous bleed)
- CF: sudden v severe headache fast peak ‘thundercalp’, occipital, N+V, meningism, coma, death, neck stiffness, positive Kernig’s sign, papilloedema, subhyaloid haemorrhage, may have ECG changes like ST elevation
- Ix: CT head (typically blood in basal cisterns, sulci or ventricles), LP if still suspect but CT negative (xanthochromia, do from 12h remains detectable for 2w)
- Refer to neurosurgery
- After confirmed look for a cause - CT angiogram +/- catheter angiogram
- Ddx: migraine (longer onset to peak and no neck stiffness), sudden benign headache, reversible vasoconstriction, acute bacterial meningitis (rupture of a micro-abscess), cervical arterial dissection
- Comps: obstructive hydrocephalus, arterial spasm causing ischaemic stroke, hyponatraemia (usually SIADH), seizures, re-bleeding
- M: bed rest, control HTN, nimodipine for 3w (CCB, thought to prevent vasospasm), also prevent vasospasm by permissive hypertension + haemodilution; treat hydrocephaluus like a drain or VP shunt; neurosurgical discussion, endovascular treatment of aneurysms
Subdural haematoma
Blood in SDS due to vein rupture, usually venous rupture (may be trivial), chronic SDH common in elderly/anticoagulants/infants as bridging veins predisposed to bleed
CF: fluctuating, headache, drowsiness, confusion, focal deficits, coma + coning may follow (nb doesnt cause meningism)
M: often resolve without drainage but need imaging + can cause death
- Acute-decompressive hemicraniectomy
- Chronic-typically over several weeks, may do burr hole drainage if symptomatic
Extradural haemorrhage
Typical occur after a skull # that tears a branch of the middle meningeal artery - blood accumulates between dura + skull
CF: brief unconscious after injury, improvement lucid interval, then lose consciousness with ipsilateral dilated pupil + c/l hemiparesis - rapid transtentorial coning
M: need urgent imaging + neurosurgery (craniotomy + evacuation of haematoma)
Causes of meningitis
- Infection from the ears/nasopharynx/head injury/meningeal defect/haematogenous
- Bacteria: N meningitides, S pneumonia (main 2 causes), S aureus, GBS (neonates), E coli, Listeria
- Viruses: enteroviruses like echo/coxsackie, HSV, mumps, HIV, EBV
- Fungi: cryptococcus neoformans, candida albicans
- May also be non-infectious like malignancy, intrathecal drugs, blood post-SAH
CF of meningitis
Headache, fever, neck stiffness, photophobia, vomiting, malaise
- Meningococcal sepsis: a/w petechial or non-specific rash, meningitis may be a part of this along with shock + peripheral vascular infarcts
- Viral causes tend to have less prominent signs + less severe sx
Management of bacterial meningitis
- Empiric: IV cephalosporin (e.g. cefotaxime), IM benzylpenicillin in community, add vancomycin in areas of high resistance
- Meningococcus - benzylpenicillin if confirmed sensitive
- Pneumonoccus + Haemophilus - cephalosporin e.g. cefotaxime
- Immunocompromised - add ampicillin to cover Listeria
- Dexamethasone to reduce oedema
- LP needed unless contraindicated. Features of bacterial include polymorphs, raised glucose and low glucose, whereas in viral the CSF may have lymphocytes but other parameters are normal
Viral encephalitis
Acute inflammation of brain parenchyma by viruses like HSV, VZV, flaviviruses like West Nile Virus.
CF: fever, meningism, personality/behavioural change, reduced consciousness, coma, seizures, focal deficits
CSF-high lymphocytes, viral PCR for the virus
M: IV acyclovir for 14-21d, anticonvulsants for seizures
Comps: RICP, midline shift/coning, long term memory impairment, personality change, epilepsy
Autoimmune encephalitis
Subacute inflammation of parenchyma due to autoantibodies
Causes include paraneoplastic syndromes, voltage gated potassium channel antibodies (usually >50y), anti-NMDA receptor antibodies (limbic encephalitis with psychiatric disturbance + seizures)
M: IV Ig, plasma exchange, steroids, rituximab, cyclophosphamide
Define status epilepticus
Continuous seizures for >5 mins
or
2 or more seizures without recovering consciousness over a similar period
What causes status epilepticus
Abrupt withdrawal of AED in a stable pt, alcohol withdrawal, hypoxia, CNS infection, fever, cancer, med change, metabolic disturbance, trauma, stroke
CF of status epilepticus
- Convulsive or not
- Absence status - continuous stuporous state
- Continuous seizure activity in one area without LoC, often a neoplasm/infarct
Management of status epilepticus
- Ensure airway patent, high flow O2
- Early up to 30m: O2, bloods (calcium, glucose, AED levels, drug screen), lorazepam IV 4mg bolus can repeat once/IV diazepam/buccal midazolam
- Established status 30-90m: IV phenytoin infusion or fosphenytoin (specialist, need cardiac monitoring)
- Ongoing seizures IV phenobarbital
- Refractory >90m: GA for intubation + ventilation, CT/MRI for a cause
What is autonomic dysreflexia?
A complication of acute cord compression at or above T6 - unbalanced physiological response to stimuli such as urinary retention –> extreme hypertension, flushing, sweating above level of lesion, agitation. If untreated can cause haemorrhagic stroke cos of the HTN
M: control the stimulus, treat HTN/bradycardia
What is cauda equina syndrome and what causes it?
Compression of the cauda equina which is the exit points of spinal nerves from L2 onwards (as the cord ends at L1-conus medullaris)
Compression basically knocks out everything below L1. Usually progressive
Causes: disc herniation esp L5/S1 and L4/5, trauma (#, subluxation), neoplasm (mets, primary), infection (discitis, Pott’s), chronic inflammation e.g. ankylosing spondylitis, iatrogenic (e.g. haematoma after epidural anaesthesia)
What are the features of cauda equina syndrome?
LMN features!
- Perianal/LL anaesthesia (often b/l)
- Painless urinary retention, may present as overflow incontinence [confirmed retention=complete CES, reduced ability to void=incomplete CES]
- Faecal incontinence - lose sense of fullness, lack of resting anal tone
- Impotence
- Reduced LL sensation (often b/l) + motor weakness
- LL motor weakness
- Severe back pain
- Hyporeflexia
Ddx: cord compression (but UMN signs), radiculopathy (painful but no urinary/anal/sexual dysfunction)
