Session 8: Neurology and Stroke Flashcards
Describe possible localisations of injury (can be applied to pattterns sensory loss as well)
Brain (post-central gyrus – somatosensory cortex)
Brainstem
Cerebellum
Spinal Cord
Anterior (ventral) Horn Cell (motor neurone diseases)
Nerve Roots (acute polyradiculoneuropathies)
Nerve (acute neuropathies)
Neuromuscular junction
Muscle (acute myopathies)
Other
Functional
Consider if its CNS/PNS
NEED TO LEARN DERMATOMES
What are upper motor neuron (pyramidal) signs?
Increased tone: spasticity (velocity-dependent; a ‘catch’ during fast extension of the elbow or fast supination of the forearm indicates spasticity – clasp knife) or rigidity (velocity independent, increased tone throughout a range movement, associated with basal ganglia disorder (extrapyramidal sign), can be lead pipe or cogwheeling, sometimes associated with tremor).
Reduced power or loss of dexterity; pyramidal distribution of weakness (U/L: flexors stronger than extensors, L/L: extensors stronger than flexors)
Pronator drift
Brisk reflexes (due to hyperactive stretch reflexes) +/- clonus
Extensor Plantars (Hoffman’s Sign/Babinski Sign)
- Hoffman’s Sign: flick terminal phalanx (hyper-extend) of the middle or ring finger=> reflex spreads pathologically (flexion of the terminal phalanx of the thumb is seen).
- Babinski Sign: extensor plantar response + fanning of toes (meant to use a painful stimulus)
What are lower motor neurone lesion signs?
Wasting and fasciculation (affected proximal part of LMN) (spontaneous electrical activity in single motor units – pathologically large – due to process of denervation and attempted repair)
Reduced tone
Weakness: pattern of weakness points to different anatomical regions
Reduced or absent reflexes
Give some pattern of weakness examples
Nerve root e.g. prolapsed disc
Mononeuropathy e.g. median nerve
Polynueropathy: distal patterning of weakness + sensory loss (glove and stocking syndrome); length-dependent (longest nerves affected earliest)
Widespread e.g. (anterior horn cell disease – MND)
Further examples:
- Pareparesis: strongly suggests spinal cord problem
- Hemiparesis e.g. due to stroke
- Monoparesis (e.g. due to brachial plexopathy, lumbar plexopathy, stroke)
- Quadriparesis/tetraparesis e.g. multiple sclerosis, muscular dystrophy (damage to the brain or the spinal cord at a high level C1-C7)
Revise Dermatomes and Cutaneous Nerves
Revise Dermatomes and Cutaneous Nerves!!!
Inguinal ligament = approx T12
Recap the Corticospinal Tracts
decussates in inferior part of medulla (at medulla oblongata in brainstem)
- Anterior fibres stay on same side
- Lateral fibres (majority of corticospinal tract) cross in pyramids of medulla
Neurones come from the motor cortex (pre-central gyrus), premotor and parietal lobe regions of the brain.
Describe the Dorsal Columns
Fasciculus gracilis and fasciculus cuneatus
Involved in proprioception and fine touch
(Discriminative touch receptor (f.Gracilis) or proprioceptor (f.Cuneatus) in the periphery => 1st order sensory neurone => 1st order neuron in f.Gracilis and f.Cuneatus tracts reach medulla oblongata => fibres cross in medulla => axons of 2nd order neurones in the medial lemniscus => thalamus receives all conscious sensations => third order neurones to cerebral cortex => Cerebral cortex: to perceptive areas for touch and proprioception
Describe the Spinothalamic Tract
Crude touch, pain and temperature
Cross at spinal cord
What is the Artery of Adamkiewicz?
In injuries informing the anterior spinal artery, dorsal columns get spared (due to blood supply from posterior spinal artery)
The Artery of Adamkiewicz is the largest anterior segment medullary artery (branch of the anterior spinal artery).
When damaged or obstructed, it can result in anterior spinal artery / anterior cord syndrome with loss of urinary and fecal continence and impaired motor function of the legs; sensory function is often preserved to a degree.
It is important to identify the location of the artery when surgically treating an aortic aneurysm to prevent damage, which would result in insufficient blood supply to the spinal cord. Its location can be identified via CT.
Describe the Posterior Spinal Artery
arises from the vertebral artery, adjacent to the medulla oblongata, reinforced by a succession of segmental branches along its pathway to form a plexus called the vasocorona. The posterior spinal arteries are seen as rather larger longitudinal channels of an extensive pial arterial meshwork – compared to the anterior spinal artery, which can be traced as a distinct channel throughout its course.
Branches from the posterior spinal arteries form a free anastomosis around the posterior roots of the spinal nerves.
It rarely gets occluded – Posterior Cord Syndrome is very rare. Clinical presentation includes loss of proprioception + vibration sense + loss of two point discrimination + loss of light touch.
What is meant by glove and stocking?
length – dependent – longest nerves affected first
polyneuropathy or symmetrical polyneuropathy is damage or disease affecting peripheral nerves (peripheral neuropathy) in roughly the same areas on both sides of the body, featuring weakness, numbness, pins-and-needles, and burning pain. It usually begins in the hands and feet and may progress to the arms and legs; and sometimes to other parts of the body where it may affect the autonomic nervous system. It may be acute (appearing suddenly, progressing rapidly and resolving slowly) or chronic (emerging and developing gradually). A number of different disorders may cause polyneuropathy, including diabetes and some types of Guillain-Barré syndrome.
What are cerebellar signs? What is Romberg’s test actually testing for?
Cerebellar Signs
- Broad-based ataxic gait
- Nystagmus (spontaneous, jerky eye movements)
- Dysarthria (slurred speech – scanning or explosive)
- Finger-Nose ataxia (dysmetria, past-pointing, intention tremor) NB: examiner needs to make sure patient is fully extending their arm
- Dysdiadochokinesia
- Heel-shin ataxia
Romberg’s Sign
- Differentiates between sensory and cerebellar ataxia
- Compares degree of unsteadiness with eyes closed versus eyes open
- If significantly more unstead when eyes closed => Positive Romberg’s Sign => Sensory ataxia (proprioceptive deficit)
What is a stroke?
Stroke: a sudden onset of focal neurological deficit from a vascular cause i.e. in a vascular territory
Two types: ischaemic and haemorrhagic but lots of subsets such as thromboemboliv, primary/secondary haemorrhage etc
What are the risk factors for stroke?
Modifiable:
- Blood pressure
- Diabetes
- Cholesterol
- Smoking / excess alcohol
- Obesity / lack of exercise
- Atrial fibrillation
- Hyper-coagulable states
- Drug abuse (cocacine0
- Infections
- Legal highs
Unmodifiable
- Male gender
- Increasing age
- Family history
Sometimes no cause is found (cryptogenic stroke = 10% of all strokes)
What is an Ischaemic Stroke? What is meant by the penumbra?
Ischaemic stroke: blood clot stops the flow of blood to an area of the brain (infarct).
Two major zones of injury: the core ischaemic zone and the “ischaemic penumbra” (the term generally used to define ischaemic but still viable central tissue.
Brain cells within the penumbra, a rim of mild to moderately ischaemic tissue lying between tissue that is normally perfused and the area in which infarction is evolving, may remain viable for several hours. This is because the penumbral zone is supplied with blood by collateral arteries anastomosing with branches of the occluded vascular tree. However, even cells in this region will die if reperfusion is not established during the early hours since collateral circulation is inadequate to maintain the neuronal demand for oxygen and glucose indefinitely.
Describe thrombolysis therapy
At best 15% stroke patients eligible – contraindications include high blood pressure, present too late, great risk of haemorrhage/bleeding etc
NOT the be all and end all
Emphasis is on multi-disciplinary care (stroke unit teams) – good nursing care and physiological parameter control are as if not more important and apply to everyone.
rTPA (recombinant TPA is used)
- 0-4.5 hours within onset. ‘Time is brain’.
- CT criteria and NIHSS (NIH Stroke Scale) scores neurological deficit – can be used to track progress.
- Bleeding risk associated with treatment
- Consider biological age vs chronological age and function
- Contraindications e.g. post-operation, arterial puncture in groin
- 0.9mg/kg. 10% bolus then rest over 60 mins infusion.
- NB: NNT =number needed to treat
What is meant by secondary prevention?
Secondary Prevention
- Depends on underlying cause
- Antithrombotic therapy vs anticoagulation. Also consider Novel Oral Anticoagulants!
- BP (aim for
- Lipid control
- Sugar control
- Lifestyle – can be difficult to get them to give up smoking if they are very disabled (need to think about quality of life)
- Carotd endartectomy (surgery to unblock a carotid artery).
NB: scan shows lobar bleed – potentially secondary bleed rather than primary.
What do the symptoms depend on?
Symptoms depend on lobes and blood vessels involved. The cerebellum can also be affected.
Note for graphic: green = ACA, red = MCA, blue = PCA. Superficial (cortical) “watershed zone” = confluence of 3 territories.
