PBL 13 - Spinal Cord Injuries

• what lesions can cause bowel and bladder symptoms

  Lesions anywhere -> bladder and bowelsymptoms
• where would a spinal lesion be for Cauda Equina Syndrome? what are the symptoms?

  -Injury at the L1 level and below resulting in a LMN lesion-Flaccid paralysis w/no spinal reflex activity
• how do urinary symptoms differ with cauda equina / nerve root / peripheral nerve lesions vs a cord lesion?

  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• Thoracic spinal stroke - anterior spinal artery• Initial spinal shock• Later develop spasticity• Tx: supportive, treat any cause
• What is spinal shock?

  Transient physiological reaction to depression of the cord below the SCI level. Associated loss of sensorimotor function and flaccid paralysis. Flaccid paralysis symptoms last several days.
• What is Brown-Sequard syndrome?

  A hemisection lesion of the cord resulting in ipsilateral motor loss and contralateral loss of sensitivity to pain and temp. Cervical spine• Causes eg tumour, inflammation (MS), trauma
• what does brown sequard syndrome result in on the same and opposite side of lesion?

  smae side as lesion:- loss of position and vibration and proprioception (DCML) posterior -UMN weakness (lateral corticospinal tract) posteriolaterally opposite side of lesion: loss of pain and temp (lat spinothalamic)
• Describe the MOA of LMW heparin

  Anticoagulant 

  Enhances the activity of antithrombin III, a natural anticoagulant in the body which inactivates clotting factors, particularly thrombin (Factor IIa) and factor Xa
• How is the risk of DVT, PE etc reduced?

  Movement, compression stockings, blood thinners.
• Can spinal cord injuries be cured?

  No BUT can prevent further damage 
• What are the 2 phases of micturition?

  Storage and voiding
• How many vertebrae do we have? How are they divided? What are their functions? How do they correlate with the spinal nerves?

  33 vertebrae divided into 5 regions FunctionsProtects the spinal cordSupports the bodyAids posture and movementWe have 31 pairs of spinal nerves - cervical pairs pass above the vertebrae apart from C7 which has a pair above and below

  
• What is the basic structure of a vertebrae?

  The 5 regions' vertebrae are all unique but have the same common structure of an anterior vertebral body and posterior vertebral arch with a vertebral canal running through which holds the spinal cordThe anterior vertebral body bears the weight and so are larger in the lower vertebraeThe posterior vertebral arch has several bony prominences which act as attachment sites for muscles and ligaments

  
• How do all vertebrae join? What does this allow for?

  Via 2 separate joints:1. Between the vertebral bodies via IV discs (cartilaginous joint) with a layer of hyaline cartilage above and below2. Between vertebral arches via articulation of superior and inferior articular facets - allows for some gliding motions between the vertebrae - allows for flexion, extension and rotation of spine!
• What is the structure of an IV disc? Whats its function?

  Their superior and inferior surfaces are lined with hyaline cartilage with a fibrocartilage IV disc between containing a nucleus propulsus and annulus fibrosisActs as a shock absorber and allows for flexibbility of the spine

  
• What ligaments strengthen the IV cartilaginous joints of the spine? What movement does each restrict?

  Strengthened by 2 ligaments:Anterior and posterior longitunidal ligaments - prevent hyperextension and flexion of the spine respectively

  
• What ligaments strengthen the superior and inferior articular facet joints of the spine? What movement does each restrict?

  1. Ligamentum flavum - between the lamina (joins spinous and transverse processes) of adjacent vertebrae - limits flexion 2. Interspinous and supraspinous ligaments - join the spinous processes of adjacent vertebrae - limit flexion 3. Intertransverse liagments - between adjacent transverse processes - limit lateral flexion

  
• Why does only 1 ligament limit extension of the spine?

  Cant extend much anyway due to spinous processes
• What is the spinal cord? Where does it run to an from?

  = A tubular bundle of nervous tissue and supporting cells made up of many nerve tracts containing similar axons/nerve fibresContinuation of the medulla oblongata to the L1/L2 IV disc = conus medullarisBelow this, it splits into the cauda equina It ends before the vertebral column as during childhood, the spine grows much quicker - creates cauda equina as spinal cord segment spinal nerves still need to exit below the corresponding vertebraArachnoid mater ends at S2 - creates large space filled with CSF - good for lumbar puncture

  
• Where does the spinal cord terminate in an infant?

  Conus medullaris at L3/4 - grow --> L1/2
• Where does the spinal cord run in the vertebrae? Where do spinal nerves emerge?

  Travels within the vertebral foramen and is surrounded by spinal meninges which continue down from the brain (3 layers - meningeal layer of the dura mater only) - spinal nerves emerge from the intervertebral foramen as a series of rootlets which form a mixed spinal nerve

  
• What protects the brain and spinal cord?

  1) Meninges (3 layers)2) Ventricular system which produce and store CSF - shock absorber and supplies nutrients to neural tissue (b-csf barrier allows specific molecules into CSF)

  
• What exists in the extradural space of the spinal cord? (above meningeal layer) What does it contain?

  Extradural fat - contains the internal vertebral plexus

  
• Describe the main arterial supply of the spinal cord and meninges

  Mianly supplied by the anterior (branch off the 2 vertebral arteries) and 2 posterior spinal arteries (branches of each posterior inferior cerebellar artery)

  
• How are the anterior and posterior spinal arteries of the spinal cord supplemented?

  Supplemented by the segmental spinal arteries(branches of the posterior IC arteries etc)Travel with the spinal roots via the interverterbal foramen and give off anterior and posterior radicular arteries which supply the spinal cord itself

  
• Which important artery helps supply the anterior 2/3 of the lumbar and sacral spinal cord?

  Artery of AdamkiewiczDamage or compromise to the artery of Adamkiewicz can lead to inadequate blood supply to the anterior spinal cord, potentially resulting in a condition known as anterior spinal artery syndrome

  
• Which part of the spinal cord is most at risk of ischaemia?

  Central area as supplied by the anterior spinal artery only and doesnt recieve additional supplementation

  
• Describe the arterial supply of the vertebrae

  Posterior IC (or pother artery depending on region) gives off other branches along with segmental branches:1. Periosteal branches which supply the vertebral body 2. Posterior branches whcih supply the vertebral arches The radicular arteries alos give off nutrient branches which sypply the deeper vertebral body

  
• Describe the venous drainage of the spinal cord and vertebrae

  Anterior and posterior spinal veins2 antereolateral and 2 posterolateral veins - run down the length of the spinal cord on either side of the dorsal and ventral nerve rootsAll drain into the anterior or posterior radicular veins which run with the corresponding arteries into the internal vertebral plexus within the extradural spaceThen drain into the external vertebral plexus (drains the vertebrae) which drain via segmental spinal veins into either:- Ascending lumbar veins- Posterior IC veinsAll drain into the azygos system

  
• What is the clinical significance of the venous drainage of the spinal cord and vertebrae?

  They are valveless - tumours can metastisise and spread from the prostate, uterus or bladder to the brain via this system
• What ligaments support the spinal cord and prevent excessive movement or displacement?

  Denticulate ligaments - delicate extensions of the pia mater which attach to the inner surface of the dura mater - suspend it in the CSF of the subarachnoid space

  
• What are the two points of enlargement on the spinal cord?

  1. The cervical enlargement is located proximally, at the C4-T1 level. It represents the origin of the brachial plexus .2. The lumbar enlargement is located between T11 and L1, representing the origin of the lumbar and sacral plexi.

  
• How is the grey matter arranged in the spinal cord?

  Arranged into 4 horns:- 2 ventral horns- 2 dorsal hornsThe ventral horns contain the cell bodies of the lower motor neuronesThe dorsal horns contain the synaptic terminals of the first order sensory neurones (cell bodies in the DRG)These horns form ventral and dorsal roots which converge to form mixed spinal nerves In thoracic spinal cord segements, there is also 2 lateral horns of grey which hold the cell bodies of pres-synaptic sympathtic neurones

  
• How is the grey matter of the spinal cord further organised?

  Into laminae - functional divisions of grey matter based on the types of neurons they contain and the roles they play in sensory and motor processing (1-6 sensory, 7 proprioception)

  
• How is the laminae of the ventral horn organised?

  Flexors more central than extensors

  
• Which laminae are involved in pain modulation?

  Lamina I (marginal zone) and V . Secondary spinothalamic neurones within this region ascend up the spinal cord and synapse with neurones within the PAG (part of reticular formation) --> activation of the RVM pathway and modulation of pain

  
• In which part of the dorsal horn do C fibres synapse? Why is this significant?

  Lamina II (substantia gelatinosa)Contains interneurones which act on the nociceptive afferent A delta and C fibres when stimulated --> modulation of pain

  
• How is white matter arranged in the spinal cord?

  Arranged into columns which contain tracts of similar myelinated axons (fascicles) - organised into functional groups

  
• What makes up a spinal cord segment? What does each give rise to?

  Each forms a mixed spinal nerve which exits out of the intervertebral foramina from nerve rootlets which form ventral and dorsal roots which unite to form the mixed spinal nerve

  
• What are the 3 key tracts within the NS and what is each responsible for?

  1) Dorsal column- Light touch, vibration and conscious proprioception2) Spinothalamic- Pain, temp, pressure and crude touch (where localsiation isnt possible e.g. itch)3) Corticospinal- Voluntary axial and limb innervation