Weakness Flashcards
What are the 5 things to consider when someone presents with weakness?
ONSET
PROGESSION OR LENGTH OF TIME
I.e. transient or ongoing
PATTERN
UMN VS LMN
PATHOGNOMONIC FEATURES
I.e. fatigability
What illnesses have an episodic trajectory?
Myasthenia gravis
Relapsing remitting MS
What are the 3 major types of illness trajectory? What are examples of conditions associated with these trajectories?
Rapid
-otherwise healthy and then sudden and dramatic decline
Eg stroke
Stepwise progression
-steady decline in health overtime with episodic dips where health declines sudden and then returns to point before
Eg Relapsing remitting MS
Slow progression
- primary progressive MS
- Neuropathies
- Myopathies
What is a decorticate posture and when does it occur?
Neck and legs extended
Hips medially rotated
Feet plantarflexed
Upper limbs in flexor pattern
Occurs when there is pathology in cortex= very severe and extensive injury i.e. TBI/ICP causing herniation
I.e. dominant muscle group take over due to disruption to inhibitory effects of tracts.
Upper extremities= flexors are dominant
Lower extremities= extensors are dominant
What is the different kinds of weakness seen in UMN compared with LMN?
UMN= pyramidal weakness
LMN= flaccid weakness
How would someone with pyramidal weakness present and why?
Elbow flexed and close to body
-due to arm flexors being stronger than extensors
Legs extended= straight leg -> circumducting gait
-due to extensors being stronger than flexors
Therefore: in stroke patients where only one side effected will have circumducting gait (Swing leg out and round walking on outside or tiptoe of this foot) and will have upper limb flexor posture on same side
What do the 3 types of UMN lesion present in terms of weakness?
Hemispheric= contralateral side weakness
Brainstem= cross lesion i.e. weakness in face on unilateral side and contralateral weakness in rest of body
Spinal cord lesion= weakness below spinal level
Why does a spinal cord stroke lead to only motor function being lost and not sensory?
Anterior spinal arteries preferentially effected which supply the ventral part of the SC containing the corticospinal tract which is the major tract associated with motor function
(Sensory tracts located in lateral and posterior)
What could cause a hemispheric or brainstem lesion pattern of weakness?
Sudden:
-stroke/infarct/haemorrhage
Subacute:
-Tumour/SOL/Abscess
What could cause a spinal cord lesion pattern of weakness?
Sudden
-spinal cord stroke
Subacute
-Transverse myelitis= cord inflammation
Progressive
- spinal tumour or mets
- spinal vascular process i.e. AV malformation or dural fistula
What condition can cause a spinal cord lesion in cervical spine?
Cervical spine osteoporosis spondylitis leads to compression of SC in the cervical segment
I.e. can present with upper limb weakness and numbness in association with headaches and neck stiffness
What happens in Brown-Sequard Syndrome and how might a patient present?
Incomplete spinal cord injury due to hemisection of spinal cord (cervical or thoracic) leading to interruption of spinal tracts on ONE side (important to consider where spinal tracts DECUSSATE)
Corticospinal tract= ipsilateral hemiparaplegia
Dorsal columns= ipsilateral loss of proprioception and vibration
Spinothalamic tract= contralateral loss of pain and temp sensation below level of spinal cord
-due to spinothalamic tract decussating at level of spinal cord rather than medulla
What is an example of LMN pattern of weakness? What condition is associated?
Polyneuropathy
-peripheral neuropathy i.e. glove and stocking sensory and motor distribution which has an ASCENDING pattern
What are the possible causes of peripheral neuropathy?
Subacute/intermediate acute (over hrs/days)
-Guillain Barre syndrome
Chronic
- Diabetic
- alcohol
- B12/folate
- hypothyroidism
- Isonizide (TB Abx)
What is Guillain-Barré syndrome? How is it diagnosed?
Acute paralytic polyneuropathy (symmetrical ascending weakness and can cause sensory symptoms) which is trigger by an infection (w/i 4 weeks of onset)
-antibodies target proteins on myelin sheath
NCS (nerve conduction studies)= will show there is reduced signal through the nerves
LP:
-raised protein
-normal cell count and glucose
Tx= IV Ig
What is the pattern of weakness seen in myasthenia gravis?
Fatigability
Motor but no sensory
Bucco-orolingual weakness
-weakness in muscles associated with mastication and swallowing
Facial + neck weakness
-neck flexors and extensors
Proximal UL and LL
Respiratory muscle weakness
What is the pattern of weakness seen in amyotrophic lateral sclerosis (ALS) MND?
Motor but no sensory
Mixed UMN and LMN signs
-LMN= wasting and fasciculations
-UMN= brisk reflexes
NOTE:
Can have bulbar/cervical/lumbar onset
How might someone with cervical spondylosis causing radiculomyelopathy present?
Neck pain Slow progressive weakness and altered sensation in hands Bilateral weakness in arms and hands Biceps and brachioradial reflexes absent UMN signs -Other reflexes brisk -Upgoing plantar Increased tone in LL
How might someone with motor neurone disease ALS present?
Progressive weakness in arms and hands over several months
Mix of UMN and LMN signs:
Wasting and fasciculation in both upper limbs (LMN)
-atrophic slow moving tongue with fasciculations
Increased tone in lower limb (UMN)
All reflexes brisk (UMN)
Upgoing plantat (UMN)
No sensory abnormalities
Speech difficulties
How might Guillain-Barré syndrome present?
Progressive weakness in lower limbs and spreading weakness to both upper limbs
Altered sensation in limbs i.e. numbness and tingling
-reduction in pinprick sensation in LL
LMN signs:
- generalised muscle weekends
- reduced tone
- absent reflexes all limbs
- normal plantar
Infection up to 4 weeks prior to symptoms
How might myasthenia gravis present?
Subacute history of symptoms
Bilateral symptoms
Eyes effected:
- ptosis
- diplopia
- opthalmoplegia (weakness in eye movement)
Proximal muscle weakness:
- difficulty climbing stairs
- difficulty reaching for high shelves
Fatigability
-symptoms worse in evening
How might someone with proximal myopathy present? What can cause this?
Chronic symptoms
Bilateral moderate proximal muscle weakness
-difficulty getting out of chair or getting up from toilet
Normal reflexes
Normal plantar
No sensory loss
Long HX of steroid medication
Causes:
- long-term steroids
- statins
- VD deficiency i.e. associated with osteomalacia
- Muscular dystrophies (BMD and DMD)
- Endocrine (thyroid disease or Cushings)
- Polymyositis
- Neoplastic (paraneoplastic)
