HNN Topic 14 - Reflex, Spinal Cord Injury Flashcards
How is sexual function and fertility managed following spinal cord injury?
- Male
- Viagra
- Cialis
- Stimulation
- Electo-ejaculation
- Female
- Assissted conception
- Pregnancy support
Where are tendon jerk reflexes tested?
Tested where there is easy access to tendon e.g. patellar tendon of knees
List the events which occur during the monosynaptic circuit of the knee tendon jerk reflex
- Stimulus - tendon tap, stretches muscle
- Activates mechanoreceptors - muscle spindle receptors
- Conduction along afferent (sensory) fibres - 1a fibres, v fast
- Transmission at synapses between 1a afferent and motor neuron associated with same muscle - ventral horn of grey matter
- Sufficient excitement (above threshold) - conduction along efferent (motor) fibres
- Neuromuscular transmission, excitation-contraction coupling
- Twitch contraction of skeletal muscle
List the signs/symptoms of spinal shock
- Flaccid paralysis
- Arreflexia
- Loss of sensation
- Loss of bladder/bowel control
How is an acute spinal injury treated?
Identify, immobilise, investigate, inform
Initial treatment = stabilisation, decompression
Describe the circuit involved in tendon jerk reflexes
Monosynaptic circuit - two neuron reflex are with central synapse (monosynaptic)
How are tendon jerk reflexes used clinically?
Gives information about sensory/motor neuropathy and CNS dysfunction
What are the benefits of using a tendon tap to test neurological intactness?
Simple, reliable (can’t be faked)
What is a lower motor neuron lesion?
- Affects nerve fibres travelling from the anterior horn of the spinal cord or the cranial motor nuclei to the relevant muscle
- I.e. peripheral nerve or at nerve root
Define autonomic dysreflexia
- Occurs in injuries occuring T6 or above
- Experience hypertension in response to noxious stimuli
- Results in headaches, can be more serious
What typically causes posterior cord syndrome?
- Trauma in neck
- Occlusion of spinal artery
- Tumours
- Disc compression
- Vitamin B12 deficiency
- Syphillus
- Multiple sclerosis
Compare the symptoms/signs of upper and lower motor neuron lesions
- Upper motor neuron lesion
- Muscle weakness
- Increased tone
- Increased reflexes
- Lower motor neuron lesion
- Muscle weakness and wasting
- Reduced tone
- Reduced reflexes
- Fasciculations
In spinal cord injuries, at what levels would upper/lower motor neuron lesion signs be present?
- Lesion C1-5 - UMN signs in upper + lower limbs
- Lesion T3-12 - UMN signs in lower limbs, upper limbs normal
- Lesion T12-S2 - LMN signs in lower limbs, upper limbs normal
What causes anterior cord syndrome?
Ischaemia of anterior spinal artery
Define reflex
Involuntary stereotyped response to a stimulus
Define tendon jerk
Reflex muscle contraction produced by tendon stretch, useful neurological test
What is the method of action of Jendrassik’s manoeuvre?
- Convert background excitation (not enough to cause firing of action potentials) to firing excitatory signals from brain, overflows to motor neuron pool of lower limb
- Continuous input from motor neuron pool - raises membrane potential/excitability closer to threshold
List the diseases which distrupt the stretch reflex and describe the impact of this
Stroke, spinal cord injury, damage to basal ganglia - change activity in descending pathways, disorders muscle tone e.g. spasticity, accompanied by exaggerated tendon reflexes (hyperreflexia)
Explain the importance of a multidisciplinary team in treating spinal cord injuries
Need medical, nursing, physiotherapy, occupational therapy, psychologist, social workers, technologist and support of family/friends
List the types of incomplete spinal cord injuries
- Central cord syndrome
- Anterior cord syndrome
- Posterior cord syndrome
- Brown-Sequard syndrome
- Cauda Equina syndrome
What is the first sign of spinal shock ending?
Babinski’s sign is one of the first reflexes to reappear after spinal shock
List the tendon reflexes tested clinically and the spinal nerves which innervate them
- Biceps (C5/6)
- Brachioradialis (C6)
- Triceps (C7)
- Patellar (L4)
- Achilles tendon (S1)
Describe the stages of reflexes returning after a spinal cord injury
- Arreflexia
- Initial reflex return
- Hyperreflexia - spasticity
Define Brown-Sequard Syndrome
Hemi-section of the cord, usually due to penetrating injury - stab, gunshot
Define neurogenic shock
- Body’s response to sudden loss of sympathetic control in a spinal cord injury above T6 (>50% sympathetic innervation lost)
- Distribution speed
- Clinical triad
- Hypotension
- Bradycardia
- Hypothermia
What is the normal function of the monosynaptic circuit?
The stretch reflex - acts to maintain constant muscle length and tone e.g. for posture
How is loss of bladder control due to spinal cord injury managed?
- Catheters - intermittent, indwelling, suprapubic, lofric, silver coated
- Infection risk - manage with antibiotics
- Liason staff, urologist
How are reflexes tested in clinical practice
- Repeat 4/5x
- Bilateral comparison
- Reinforcement
- Lower limb = Jendrassik’s manoeuvre
- Upper limb = clench jaw
Describe the clinical manifestations of Brown-Sequard Syndrome
- Paralysis of affected side (corticospinal)
- Loss of proprioception + fine discrimination (dorsal columns)
- Pain + temperature loss on opposite side below the lesion (spinothalamic)
What are the priorities of patients with spinal cord injuries?
- Depends if tetraplegic or paraplegic
- Paraplegic - walking, bladder/bowel
- Tetraplegic - arm/hand, walking
- Older patients - sexual function not top priority
- Changes over time - long-term bladder/bowel and chronic pain become very important
In what situation can tendon jerk reflexes be absent?
Holmes-Adie syndrome
How is the loss of bowel control managed after spinal cord injury?
- Diet, lactulose, senna
- Manual evacuation
- Bowel regime needed
Describe how respiration is affected by spinal cord injuries at specific levels
- C3, 4, 5 - diaphragm (phrenic nerve)
- Injury above this level - no respiratory muscle function
- Intercostal muscles - C6/7
- Injury C4-6 - breathing occurs but no accessory muscle function, problems coughing
- Below C6/7 - breathing not affected
- Above C6 - may need tracheostomy + artificial ventilation
How is bladder control affected by spinal cord injuries?
- Micturition centre = S2-4, most injuries result in degree of loss of bladder control
- Injury at S4/5 - some control
- May struggle to empty bladder - loss of sympathetic control in hypogastric nerve (T12-L1)
In which situations is Babinski’s sign present and why?
- Babies up to 1 year and spinal cord injuried show Babinski’s sign
- Two pathways - flexion and extension
- In neurologically intact adults - extensor pathway suppressed by corticospinal tract
- In neonates corticospinal tract is not fully mature (unmyelinated)
- Damage to corticospinal tract e.g. spinal cord injury - re-emergence of Babinski’s sign
What causes cauda equina syndrome?
Bony compression or disc protrusions in lumbar or sacral regions
Describe the ASIA scale ranking of spinal cord injury
A = No sensory/motor function below level of injury
B = Sensory (S4/5) but no motor function below level of injury
C = Less than grade 3 motor function below level of injury
D = Grade 3 or above motor function below level of inury
E = Neurologically intact
What type of injury typically causes central cord syndrome?
- Typically older patients
- Hyperextension injury
- Compression of cord anteriorly by osteophytes, posteriorly by ligamentum flavum
What is the outcome of central cord syndrome?
Loss of motion and sensation in arms and hands
What are the differences between quadreplegia and paraplegia
- Quadraplegia
- Injury in cervical region
- All 4 extremities affected
- Paraplegia
- Injury in thoracic, lumbar or sacral segments
- 2 extremities affected
How is a spinal cord injury assessed?
ASIA Chart
- Motor = upper limb, lower limb, anal contraction
- Sensory = pin prick, light touch, sacral sparing
- Motor
- Sensory
- Bladder
- Bowel
- Sexual
- Autonomic
How is pain managed following spinal cord injury?
Rehabilitation consults, anaesthetic pain service, pain nurse
What is the outcome of anterior cord syndrome?
Loss of function of anterior 2/3 of spinal cord - loss of voluntary motor function (corticospinal tract) below injury, loss of pain/temperature sensation (spinothalamic tract) but retained proprioception and vibration sensation (DMCL)
Describe the clinical manifestations of cauda equina syndrome
- Non-specific symptoms - back pain
- Bowel + bladder dysfunction
- Leg numbness and weakness
- Saddle paraesthesia
Describe how limb function is affected by spinal cord injuries at specific levels
- C1-4 - quadreplegia
- C5 - shoulder, biceps - no wrist/hand control
- C6 - wrist control, no hand movement
- C7/T1 - most upper limb control, fine dextrous control of hands/fingers affected
- T1-8 - paraplegia, poor control of trunk/abdominal muscles
- Lumbar/sacral - decreased control of hip flexors + legs
Define spinal shock
- Temporary suppression of all reflex activity below the level of injury, occurs immediately after injury
- Can last for 30 minutes - 6 weeks after injury
List the common complications of spinal cord injuries
- DVT, pulmonary embolism - high risk due to immobility, prophylaxis
- Asensate skin - pressure sores, recumbency (lying down), death
- Pain - acute and chronic
- Loss of sexual function and fertility
- Autonomic dysreflexia
Describe normal and abnormal plantar reflexes
- Normal plantar reflex = toe flexion
- Babinski’s sign = toe extension
What is the stretch reflex
Prolonged stretch produces prolonged (tonic) contraction, influenced by descending pathways from brain - can change excitability of motor neuron pool
What is an upper motor neuron lesion?
- Lesion of neural pathway above the anterior horn cells of the spinal cord or motor nuclei of the cranial nerves
- In brain/spinal cord e.g. cerebral infarction or lesion to the corticospinal tract
