Neuro Flashcards
Approach to interpreting Motor signs
If just motor signs, think about: - UMN (brain/brainstem/spinal cord) - LMN (Ventral nerve root/Peripheral nerve (most likely GBS)) - Mixed UMN and LMN = MND ○ ALS signs: § Weakness § Wasting § Fasciculations § Hyperreflexia § Spasticity
Approach to interpreting sensory signs
If just sensory signs, think about the distribution:
- Dermatomal (nerve root pathology most likely) - Glove and stocking (peripheral neuropathy) - Affecting a single peripheral nerve sensory distribution - Sensory level (spinal cord pathology)
Approach to interpreting mixed signs
If mixed signs, think about whether the motor signs are UMN or LMN:
- If LMN: has to be a peripheral neuropathy (could be any, less likely to be diabetic as there is motor involvement) - If UMN: most likely spinal cord pathology (e.g. SCDC)
Likely patterns of signs in:
Brain, Spinal cord, nerve root, peripheral nerve and NMJ
- Brain
○ Contralateral UMN signs, +/- sensory signs- Spinal cord
○ Ipsilateral UMN signs, +/- ipsilateral fine touch/vibration loss and contralateral pain and temperature loss e.g. SCDC - Nerve root (radiculopathy)
○ Ventral = Isolated ipsilateral LMN signs (weakness, atrophy, flaccidity) in distribution of that nerve root
§ Most common is L5 radiculopathy, leading to foot drop
○ Dorsal = Isolated sensory deficit in dermatomal distribution
- Spinal cord
○ Causes § Intervertebral disc herniation § Spinal stenosis § Spondylosis § Infection (CMV in HIV, Lyme disease)
- Peripheral nerve ○ LMN signs + sensory deficit in peripheral nerve distribution (classically glove and stocking) § Commonly predominantly sensory neuropathy - the only mainly motor peripheral neuropathy is GBS ○ Can be: § Mononeuropathy: Affects 1 nerve § Mononeuritis multiplex: Affects several different peripheral nerves e.g. diabetic neuropathy § Polyneuropathy: Affects most - NMJ ○ Widespread LMN signs only, with no sensory deficit
What is pronator drift?
Sign of an UMN lesion e.g. stroke
2 types of tone
- Spastic (clasp-knife) hypertonia (resistance increases with speed of stretch until it suddenly releases)
Pyramidal hypertonia, affecting the flexors more than the extensors, so normally presents with an arm that is flexed at the elbow, wrist and fingers- Lead pipe rigidity
Hypertonia in all modalities that isn’t velocity dependent (cogwheeling is due to modification of leadpipe rigidity by tremor)
- Lead pipe rigidity
2 spinal cord pathologies that preferentially affect the spinothalamic tract
- Anterior spinal artery occlusion
- syringomelia
Causes of spastic paraparesis
○ Bilateral strokes
○ Syringomelia
○ Cord trauma
○ Extrinsic cord compression (tumour, disc prolapse, spondylosis)
○ Intrinsic cord disease (tumour, vascular myelopathy, MS)
Causes of flaccid paraparesis
○ Polio ○ Motor peripheral neuropathy § GBS ○ Mixed peripheral neuropathy § Charcot Marie Tooth disease
Causes of peripheral neuropathy
- Predominantly sensory
○ Diabetes
○ Uraemia- Predominantly motor
○ GBS
- Predominantly motor
- Mixed ○ CMT disease ○ Alcohol ○ B12 deficiency ○ Vasculitis ○ Thiamine deficiency
What is hyperdense MCA sign
Early sign of acute ischaemic stroke: Can directly visualise the hyperdense thrombus within the MCA on a CT
Causes of proximal myopathy
Drugs e.g. statins, steroids
Endocrine pathology (Cushing’s, hypothyroidism)
Inflammatory e.g. polymyositis
PMR (is pain not weakness, so is a mimic)
What are the 2 most common radiculopathies
Cervical radiculopathy, most commonly C7 (causing hand paraesthesia + wrist weakness)
Lumbar radiculopathy, most commonly L5 (causing foot drop)
Causes of radiculopathy
Posteriolateral disc herniation
Spinal abscess
Spondylosis
Spinal stenosis
TIA mimics
Migraine
Epilepsy
Cerebral tumour
Hypoglycaemia
