Neurology Flashcards
Describe the corticospinal tracts
Descending pathway for motor control
Located in the white mater of the spinal cord, laterally or ventrally (anterior)
The UMN travels from the primary motor cortex through the internal capsule, the 85% of the fibres decussate at the medulla to from the lateral corticospinal tract (remainder form the ventral tract)
They synapse with the LMN in the ventral grey horn and the axons leave in the spinal nerve
What does a lesion of the corticospinal tract cause?
Ipsilateral weakness of muscles
Describe the dorsal column pathway
An ascending tract for touch, proprioception, and vibration
Located in the dorsal white matter of the spinal cord
The cuneate fasciculus (more lateral) carries information from the upper limbs, and the gracile fasciculus (more medial) carries information from the lower limbs
Primary sensory neurons ascend in the ipsilateral dorsal columns and synapse with the 2nd neuron at the cuneate/gracile nucleus (in medulla)
The 2nd neuron decussates in the medulla then ascends to the thalamus, where is synapses with the 3rd neuron, which then projects to the somatosensory cortex
What does a lesion of the dorsal column pathway cause?
Ipsilateral impairment/loss of fine touch, proprioception, and vibration
Describe the spinothalamic tract
An ascending tract for pain and temperature
Located in the ventrolateral white matter of the spinal cord
The primary sensory neuron synapses with the 2nd neuron in the grey horn, and this decussates then ascends
It synapses with the 3rd neuron in the thalamus which then projects to the somatosensory cortex
What does a lesion in the spinothalamic tract cause?
Contralateral impairment/loss of pain and temperature sensation
Define cerebrovascular event (stroke)
A clinical syndrome caused by disruption of blood supply to the brain (due to infarction or haemorrhage), characterised by rapidly developing signs of focal or global disturbance of cerebral functions, lasting for more than 24 hours or leading to death
Define ischemic stroke
An episode of neurological dysfunction caused by focal cerebral, spinal, or retinal infarction (cell death due to lack of blood supply)
What are the 5 types of ischemic stroke?
Large vessel disease (atherosclerosis/thrombosis)
Small vessel disease (microathermoma, lacunes)
Cardioembolic (caused by AF, endocarditis, mural thrombus)
Other (rare causes e.g. vasculitis, venous thrombosis, carotid dissection)
Undefined
Define stroke due to primary intracerebral haemorrhage
Rapidly developing clinical signs of neurological dysfunction because of a focal collection of blood within the brain parenchyma or ventricular system, which is not caused by trauma
*secondary intracerebral haemorrhage = due to trauma, blood thinners etc.
Define stroke due to subarachnoid haemorrhage
Rapidly developing signs of neurological dysfunction and/or headache (thunderclap) because of bleeding into the subarachnoid space, which is not caused by trauma
What are the risk factors for strokes?
Lifestyle factors:
- smoking
- alcohol misuse
- physical inactivity
- poor diet
Established CVD:
- hypertension
- AF
- infective endocarditis
- IHD
- congestive heart failure
- structural defects
Other medical conditions:
- migraine
- hyperlipidaemia
- diabetes mellitus
- hypercoagulable disorders
- connective tissue disorders
Non-modifiable factors:
- older age
- male sex
- personal/family history of stroke/TIA
- lower level of education
What are the signs/symptoms of a stroke in the anterior circulation?
Either hemisphere (symptoms contralateral):
- hemiparesis (upper limb = MCA, lower limb = ACA)
- hemisensory loss (upper limb = MCA, lower limb = ACA)
- visual field defect
Dominant hemisphere (usually LEFT hemisphere)
- language dysfunction (expressive/receptive dysphasia, dyslexia, dysgraphia)
Non-dominant hemisphere (usually RIGHT hemisphere)
- visuospatial dysfunction (geographical agnosia, dressing apraxia, constructional apraxia)
- anosognosia (impaired understanding of their illness, neglect of paralysed limb, denial of weakness)
What are the signs/symptoms of a stroke in the posterior circulation?
Unsteadiness
Visual disturbance
Slurred speech
Disorder of perception
Headache
Vomiting
Others e.g. memory loss, confusion
What investigations are needed for a stroke?
CT head (1ST LINE, without contrast, ideally within 1 hour)
MRI brain with diffusion weighted imaging (GOLDSTANDARD)
Blood tests (FBC, U&E, ESR, TFTs, glucose, lipids to asses general health and exclude other causes)
ECG (look for arrhythmias and cardiac causes)
ECHO (may show mural thrombus, valvular lesions)
Carotid Doppler ultrasound, or CT/MRI angiogram (asses carotid artery stenosis)
What are the treatments for an ischemic stroke?
ABCDE
Oxygen as needed
Maintain blood pressure and glucose
Antiplatelets (e.g. aspirin) - only once haemorrhagic stroke is ruled out
Thrombolysis - only within 4.5 hours of onset, and if haemorrhagic stroke is ruled out, most effective in 1st 90 mins
Thrombectomy - for larger arterial occlusions
What is the primary prevention for strokes?
Control risk factors:
- asses and treat hypertension, DM, hyperlipidaemia, cardiac disease
- smoking cessation
- exercise
Long term anticoagulants
- e.g. warfarin/DOAC
- in AF or prosthetic heart valves
What is the secondary prevention for a stroke?
Antiplatelets: short-term = aspirin, long-term = clopidogrel
Anticoagulants if cardiac cause (warfarin/DOAC)
Investigate and treat risk factors: hypertension, hyperlipidaemia, cardiac disease, carotid artery stenosis, etc.
Define TIA
Transient ischemic attack:
Transient (less than 24 hours) neurological dysfunction caused by focal cerebral, spinal, or retinal infarction
What are the signs/symptoms of TIA?
*symptoms come on suddenly and usually resolve after 1 hour but can persist up to 24 hours
Focal neurological defects:
- unilateral weakness/sensory loss
- dysphasia
- ataxia, vertigo, loss of balance
Cranial nerve defects
Amaurosis fugax (sudden transient loss of vision in one eye
What are the treatments for a TIA?
Control cardiovascular risk factors (blood pressure, lipids, glucose)
Antiplatelets: short-term aspirin, long-term (secondary-prevention) = clopidogrel
Anticoagulants (warfarin/DOAC) is cardiac cause
Carotid endarterectomy (reduce stenosis)
How is the risk of having a stroke after a TIA assessed
ABCD2 =
Age (>60)
Blood pressure (>140/90)
Clinical features (weakness, speech disturbance)
Duration of symptoms
Diabetes
Higher score = higher risk = urgent referral
Describe the epidemiology of brain tumours
Mostly affects younger patients
55% malignant
How are brain tumours categorised?
Cell type: gliomas (most common - e.g. astrocytoma, ependymoma, oligodendrocytoma)
Location: meninges, sellar region, germ cell tumours (pituitary/pineal region)
Cranial nerve involvement (schwannoma)
Secondary/metastatic
Molecular markers
Genetic factors