Neurology Flashcards
What is the Upper motor neurone?
corticospinal (=pyramidal) tracts: pathways that carry motor information
from the precentral gyrus of the frontal cortex up to the synapse with anterior horn cells in the spinal cord (via the internal capsule, brainstem, and cord).1
What is a pyramidal pattern of weakness mean?
UMN weakness affects groups rather than individual muscles, typically in a ‘pyramidal’ pattern: in
arm ->extensors are weaker
Leg -> the opposite -> flexors are the weaker muscle group
What are UMN signs?
- Spasticity - in stronger muscle(arm flexor + leg extensor) -> increased tone -> velocity dependent -> more movement = more resitance = clasp knife
- Muscle wasting less so
- Hyperreflexia(brisk reflex)
- Upgoing plantars (babinski)
- Clonus (>3 as less than 3 normal)
- Loss of skilled fine finger movement
- UMN and LMN similiar in first few hours before spaticity - hyperreflexia develop
Where is the LMN?
Anterior horn cell distally - nerve root, plexus, peripheral nerved
LMN signs
- Muscle wasting
- Fasciculations
- Hypotonia/flaccidity
- Reflex reduced or absent
- Plantar flexion normal
What does primary muscle disease show signs off
- Symmetrical muscle loss
- Normal reflex or lost late
- No sensory loss
Where do pain fibres pass through and where do propioception travel through?
Pain -> spinothalamic(anterolateral tract) + peripheral nierves
Proprioception and vibration -> large fibres in peripheral nerves and large dorsal columns
What are the different grades of the MRC classification of muscle weakness
Grade 0 No muscle contraction
Grade 1 Flicker of contraction
- Grade 2 Some active movement
- Grade 3 Active movement against gravity
- • Grade 4 Active movement against resistance
- Grade 5 Normal power (allowing for age)
Cortical lesion signs
- Localised problem with hand or foot
- Normal or reduced tone
- Increased reflexes with more proximal muscle -> UMN >LMN
- Sensory loss in a specific area
Internal capsule and corticospinal tract lesion cause what
contralateral hemiparesis(UMN), generalised contralteral sensory loss.
Cranial nerve palsy contralateral to hemiplegia -> brainstem on the side of the cranial nerve palsy
Lateral brainstem lesions shows
lesions show both
dissociated and crossed sensory loss with pain and T° loss on the side of the face ipsilateral to the lesion, and contralateral arm and leg sensory loss
Cord lesion gives you?
causing paraparesis (both legs) or quadriparesis/tetra plegia (all limbs) are suggested
by finding a motor and reflex level (power is unaffected above the lesion, with LMN signs at the level of the lesion, and UMN signs below the lesion). A sensory
level is the hallmark (albeit a rather unreliable one)—ie decreased sensation below
the level of the lesion with normal sensation above.
Brown-sequard (hemicord lesion) causes what
dorsal column loss on the side of the lesion and
contralateral spinothalamic loss.
When might you get dissociated sensory loss(so fine touch and proproprioception find but no loss of pain and temperature)
cervical
cord lesions—loss of fi ne touch and proprioception without loss of pain and
temperature (or vice versa, eg syringomyelia; or cord tumours).
Peripheral neuropathies
Most cause distal weakness, eg foot-drop; weak hand (note:
although Guillain–Barré syndrome typically presents as distal weakness that ascends over time, some atypical forms of Guillain–Barré syndrome may present with proximal weakness due to nerve root involvement).
Sensory loss is typically worse distally (may involve all sensory modalities or be selective, depending on
nerve fibre size involved). Involvement of a single nerve (mononeuropathy) occurs with trauma or entrapment (carpal tunnel, p503); involvement of several nerves
(mononeuritis multiplex) is seen, eg in DM or vasculitis.
Sensory loss from individual nerve lesions will follow anatomical territories (dermatomes, p454), which are usually more sharply defined than those of root lesions
