spinal cord injuries

• • Neuroanatomy is the road map for localisation

  • Nervous system:

  • Brain , Brainstem , Spine (CNS)

  • Nerve roots , Plexi , Nerves , Neuromuscular junction , Muscles (PNS)
• UMN (lesion in brain or spine) – lack of  higher control

  • Pyramidal weakness (flexors stronger than extensors in arms, extensors stronger than flexors in legs)
  • Spasticity
  • Brisk reflexes
  • Upgoing (extensor) plantar reflex (Babinski sign )
  • Clonus
• clonus

  precise pathophysiology unknown, but there are 2 leading theories

  • clonus is caused by a self-perpetuating reactivation of peripheral muscle stretch circuits, with each beat producing the next.
  • On the other, there is an initial appropriate external stimulus that leads to activation of the stretch reflex circuit followed by a central signal which commands the muscles to continue to produce that motor response in the absence of an appropriate stimulation of the stretch reflex. A complete explanation may be a combination of the 2 theories
• clonus:

  • Hyperexcitability in muscle stretch circuits produced when there is less tonic inhibition of motor neurons in monosynaptic stretch reflex.
  • maybe due to lesion to descending motor nerves, in dorsal reticulospinal pathway, which can occur anywhere from the cortex to the spinal cord
  • inhibitory dampening effect of these descending nerves on alpha and gamma motor neurons is removed -> hyper excitatory state in the muscle stretch reflex circuit
  • Therefore, clonus is considered a manifestation of upper motor neuron pathology
• LMN (lesion in nerve root, plexi, peripheral nerve)

  • Flaccid weakness
  • Normal or reduced tone
  • Reduced or absent reflexes
  • Wasting
  • Fasiculation (sign muscle de-afferented i.e. no nerve supply)
• Stroke with hemiparesis flexed upper arm and circumducted legs, indicative of pyramidal sign
• important neuroanatomy

  • Cord- Base of skull to conus medularis (L1/2)

  • Cervical and lumbar enlargements

  • Cauda equina (L1-L5)

  
• LEARNING POINT 1:

  •Lesions in the cervical and thoracic spine -> UMN

  •Lesions in lumbar spine -> LMN

  •Lesion in conus -> UMN and LMN
• LEARNING POINT 2:

  •Lesion in the cervical cord -> arms and legs

  •Lesions in thoracic cord -> legs

  •Lesions anywhere -> bladder and bowel symptoms
• Spinal cord functions:

  • Sensory information from the body to the brain (afferent)

  • Motor control from brain to body (efferent)

  Includes bladder, bowel and sexual function

  • Autonomic function from brain to body

  • Spinal reflexes
• posterior dorsal columns ( sensory - vibration , proprioception and joint position sense )

  lateral corticospinal tract ( motor )

  spinothalamic tract ( sensory - pain , temp )
• posterior dorsal columns ( sensory - vibration , proprioception and joint position sense )

  lateral corticospinal tract ( motor )

  spinothalamic tract ( sensory - pain , temp )

  
• two main sensory inputs

  •The dorsal column (proprioception and vibration) ascends in the DORSAL (posterior) part of the spinal cord and crosses over in the MEDULLA (after the spinal cord)

  •The spinothalamic tract crosses over immediately in the SPINAL CORD and ascend in the LATERAL part of the spinal cord

  
• •Motor tracts cross over in the MEDULLA (before reaching the spinal cord) and descend mainly in the LATERAL spinal cord
• LEARNING POINT 5

  autonomic tracts

  •Spinal lesions can cause autonomic dysfunction, including Horner’s syndrome and blood pressure dysregulation
• Lesions in cervical/thoracic spinal cord:

  • Pyramidal weakness of arms and legs (cervical) or legs (thoracic)

  • Spasticity

  • Brisk reflexes, upgoing (extensor) plantar reflexes

  • Sensory level

  • Sphincter involvement

  Lesions in lumbar spine (cauda equina)

  • Flaccid weakness

  • Normal reduced/tone

  • Reduced or absent reflexes

  • Patchy leg sensory reduction

  • Sphincter involvement (reduced anal tone)
• Transverse myelitis

  •  inflammation of part of the spinal cord. The exact cause is often not known, but it sometimes happens after infections or in people with autoimmune diseases. Common symptoms are back or neck pain, weakness or sensation changes in the arms or legs, or loss of bladder or bowel control.
  • Sub-acute, female – likely inflammatory
  • Treatment: high dose steroids +/- other immunosuppression
• Cauda equina syndrome

  a rare and severe type of spinal stenosis where all of the nerves in the lower back suddenly become severely compressed. Symptoms include: sciatica on both sides. weakness or numbness in both legs that is severe or getting worse. numbness around or under your genitals, or around your anus. LMN involved and it is a neurosurgical emergancy
• urinary symptoms:

  Cauda equina / nerve root / peripheral nerve lesions:

  • Hesitancy, poor stream, retention, overflow incontinence

  • Bladder emptying symptoms

  Cord lesion:

  • Urgency, frequency, urge incontinence

  • Overactive bladder, may also get urinary retention if bladder - sphincter dysynergia
• Spinal stroke

  • Much rarer than cerebral stroke ( cause can be ischaemic or haemorrhagic )

  • Initial spinal shock

  • Later develop spasticity

  • Tx: supportive, treat any cause
• Spinal shock is the altered physiologic state immediately after a spinal cord injury (SCI), which presents as loss of spinal cord function caudal to the level of the injury, with flaccid paralysis, anesthesia, absent bowel and bladder control, and loss of reflex activity.
• the spinal cord is supplied by anterior and 2 posterior arteries at different levels, these arteries stem from segmental arteries coming off the aorta ( the vertebral arteries have some input towards the top )

  
• Brown-Séquard syndrome a neurologic syndrome resulting from hemisection of the spinal cord. It manifests with weakness or paralysis and proprioceptive deficits on the side of the body ipsilateral to the lesion and loss of pain and temperature sensation on the contralateral side.

  causes can be a tumour, inflammation (MS) , trauma . TX depends on the cause
• Subacute combined degeneration is characterized by degeneration of the dorsal columns and the lateral columns of the spinal cord due to demyelination. It commonly presents with sensory deficits, paresthesia, weakness, ataxia, and gait disturbance. In severe untreated cases, it can lead to spasticity and paraplegia

  •Other classical condition affecting posterior cord – tabes dorsalis (syphilis)
• Subacute combined degeneration of the cord

  • Usually from vitamin B12 deficiency e.g. very poor or restricted diet, pernicious anaemia. Also copper deficiency, nitrous oxide abuse – more common in recent years)

  • Often co-existing peripheral neuropathy

  • Treatment : B12 replacement
• What is syringomyelia? a neurological disorder in which a fluid-filled cyst (syrinx) forms within the spinal cord (in the central canal where there is CSF). The syrinx can get big enough to damage the spinal cord and compress and injure the nerve fibers that carry information to and from the brain.
• Syringomyelia

  • Central lesion affects crossing spinothalamic

  • Can extend to involve anterior horn cells and sympathetic (Horner’s – if C8-T1) and eventually corticospinal

  • Causes eg congenital (association with Chiari malformation), trauma, malignancy -> slip into the foramen magnum -> bocks the exits where CSF could get into the arachnoid space -> fluid backs up -> hydrocephalus / into the spinal canal causing syringomyelia

  • Treatment: conservative, neurosurgical
• Spinal cord injury management

  •Acute management depends on aetiology e.g. neurosurgical stabilisation of fracture, immunosuppression for inflammation

  •Spasticity – anti-spasticity medication eg baclofen, botulinum toxin

  •Pain – neuropathic pain medication, nerve root blocks

  •Bladder dysfunction – B&B team, bladder relaxant medication, ISC, botulinum toxin

  •Bowel – laxatives, bowel irrigation

  •Skin – nursing care, specialist mattresses

  •Respiratory function (esp high cervical) – respiratory support
• Autonomic dysreflexia

  • Sudden rise in BP

  • Variable sympathetic features

  • E.g. nasal congestion, flushing, goosebumps

  • Check BP:

  200/100 or rise above baseline of 20-40mmHg

  • SIT UPRIGHT

  • BLADDER - Patent catheter

  • RECTUM - PR with lidocaine gel, remove any faeces

  • DRUGS - NIFEDIPINE OR GTN SUBLINGUAL

  • HDU/ICCU and IV treatment – hydralazine, labetolol