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What causes LMN signs
Damage from anterior horn cells including nerve roots, plexus and peripheral
What are LMN signs
Ipsilateral FLACCID muscle paralysis Muscle wasting / atrophy Fasiculation Hypotonia Hyporeflexia
What is top differential of a LMN lesion and how do you differentiate
Primary muscle disease
- Usually more symmetrical
- Proximal muscles more affected
- Reflexes normal
- No sensory signs
What causes fasciculation
Increased receptor concentration to compensate for lack of innervation
What causes UMN signs
Damage anywhere along corticospinal tracts (pyramidal) -> pre central gyrus of frontal cortex
How does UMN present
Ipsilateral SPASTIC paralysis Muscle weakness Hypertonia Hyper-reflexia Extensor plantar 'Babinski' Sustained clonus
What pattern of muscle weakness
Pyramidal
Extensors weaker in arms
Flexors weaker in legs
If lesion above decussation what type of paralysis
Contralateral
If below
Ipsilateral
What types of hypertonia do you get
Spastic
Rigid
What is spastic
Increased tone that reaches a point then break
Velocity dependent
The faster you move the more resistance until it gives way
What is rigid
Increased tone through whole range
What is important to remember
UMN lesion can mimic LMN. due to spinal shock before spasticity and hyperreflexia kick in
Biceps reflex
C5/6
Supinator reflex
C6
Triceps reflex
C7
Hip flexors reflex
L2
Knee extensor
L3/4
Ankle plantar flexor
S1
What are sensory modalities
Pain Temp Touch Vibration Joint position
What tract do pain and temp go up
Lateral Spinothalamic
What tract do joint position and vibration go up
Large dorsal column
If lesion in spinothalamic tract where is loss
Contralateral as cross as soon as enters
If lesion in dorsal
If above decussation = contralateral
If below = ipsilateral
What is brachial plexus divided into
Roots
Trunk
Division
Cords
What supplies the brain
Circle of Willis
What makes up circle of Willis
ICA (anterior)
Basillar artery (posterior) - formed by 2 vertebral
Vertebral
What does vertebral supply
Brain stem
What does ICA supply
Anterior 2/3 of cerebral hemisphere + basal ganglia
What does ICA split up into
Anterior cerebral
Middle cerebral
Posterior cerebral
What does anterior cerebral suppy
Frontal and medial part of cerebrum
If occlusion
Weak, numb contralateral leg or arm
Face is spared
What does middle cerebral supply
Lateral hemisphere
Basal ganglia
If occlusion
Contralateral homonymous hemianopia
Cognitive change if dominant hemisphere
Visuo-spational disturbance if non-dominant
What does posterior supply
Occipital lobe
If occlusion
Contralateral homonymous hemianopia
What does vertebrobasillar supply
Cerebellu, brain stem and occipital lobe
What can occlusion cause
Hemianopia Cortical blidness Diplopia Vertigo Nystagmus Ataxia Dysarthria Dysphasia Hemi or quadraplegia Can be uni or bilateral Hiccups Coma
What syndromes arise due to infarctions of brains stem
Lateral medullary
Locked in
Important
Differentiate lesion
e.g. UMN vs LMN etc.
Spastic paraparesis DDX
MS
Cord compression
Stroke
Spastic hemiparesis DDx
Stroke
Tumour
MS
Parkinsonism DDX
PD
Vascular
Drug
Cerebellar DDX
Alcohl
Stroke
MS
3rd nerve palsy medica
DM
HTN
Stroke
3rd nerve palsy surgical
Aneurysm
Tumour
ICH
4th nerve palsy
Trauma
Bulbar palsy
Stroke
- affect LMN as leave brainstem
MND
MG
Pseudobulbar
Stroke
MND
MS
Mixed
MND
Cervical spondylosis
SACD
Acute bilateral leg weakness
Cord compression
Cauda equina
Acute unilateral food drop
DM Common perineal palsy Prolapse MS Stroke
Chronic spastic paraparesis (UMN)
MS MND Malignancy of cord Syringomyelia B12 Infection
Chronic flaccid
Peripheral neuropathy
Myopathy
What does sensory loss suggest
Spinal cord issue
What does loss of bladder / bowel suggest
Cauda eeqina
If acute / sudden
Cord compressio
If raised inflammatory
Infectious
dDx of spinal issue
Infarct
- Hyperacute + vascular RF
Discitis
- IVDU / immunosuppressed / fever
Cord compression
- Back pain
- Red flag Sx / Hx malignancy
