Spinal injury and anaesthesia Dr Ashish Moderator :Dr R.Tope

Introduction Anaesthesiologists are often involved in the initial resuscitation and management of trauma victims with possible cervical spine injuries They have a role on site, during transport, in O.T and in ICU They should recognize the situations in which such injuries are likely Be familiar with evaluation of the cervical spine Understand the pathophysiology of the spinal cord injuries Evaluate the risks and benefits of alternative approaches to anesthesia and airway management

Clinical Anatomy The upper two and the lower five cervical vertebrae differ both anatomically and functionally. The occipito- atlantoaxial unit is the most complex osseus articular structure. It supports the head while enabling flexion extension and rotation of upper neck.

Clinical Anatomy Atlas the first cervical vertebra has thick anterior and posterior arches. The upper surface articulates with the occipital condyles and the inferior surface articulate with axis. Transverse ligament encloses the odontoid peg, (Dens) of the axis.

Clinical Anatomy Axis, the second cervical vertebra has a central upward extension, the dens. The Alar and apical ligaments fan up from the dens to insert into the anterior margins of the foramen magnum.

The lower five vertebrae are typical cervical vertebrae, have transverse processes containing a fenestrations to permit the passage of vertebral artery. anterior longitudinal ligament The anterior longitudinal ligament passes upwards and gets inserted into base of the skull as the anterior altanto occipital ligament. Posterior longitudinal ligament fans out over body of the axis, the odontoid peg and inserted into basiocciput as tectorial membrane. Supraspinous ligament is called as ligamementum nuchae.

Three column concept Vertebral column consist of three components Anterior column – ant 2/3 of vertebral body,disc,annulus, and ant. Long. Ligament Middle column – post 1/3 of vertebral body,disc, annulus, and post. Long. Ligament Posterior column – pedicles, laminae,facets,capsule,interspinous and supraspinous ligament. Flexion injury cause disruption of posterior column Extension injury cause disruption of anterior column Any injury resulting in damage to 2 or > column or risk neurologic injury are considered unstable

Epidemology of acute cervical spine injury Causes : Motor vehical accident % Fall(older age) - 20% Recretional activity % Gunshot wound Population & age – male age(4x more common than women) Site of injury- C5-C6 most frequent Neurologic function after injury Quadriplegia – 23.7% Central cord syndrome -17.3% Anterior cord syndrome -4.9% Brown sequard syndrome – 3.7% Other - 42%

Hyperextension Hyperflexion Compression Rotation Lateral Stress Distraction

Cervical spine involvement 2% victims of trauma 6% craniofacial injury, Glasgow scale <8 Spine protection measures MILS: Preferred Semi rigid collar Lateral head support MILS vs Collar Collar: not complete protection complicate airway during CPR increase ICP, in head injury interfere with intubation effort

Initial assessment and immobilization History  Pain/paresthesias  Transient or persistent motor or sensory symptoms *Physical Examination  Abrasions/hematoma  Tenderness  Interspinous process widening

Immobilize the casualty’s head and neck manually Apply a cervical collar, if available, or improvise one Secure patient to short spine board if extracting from a vehicle Secure head and neck to spine board for extraction

Transfer patient to long spine board as soon as feasible Logroll in unison Stabilize head and neck with sandbags or rolled blankets

Spinal Boards

Spinal Log Roll

(Note: spinal alignment as indicated by black line)

Spinal immobilisation Cervical spinal immobilisation before to radiographic assesment To prevent excerbation of neurological injury in patient with unstable cervical spine Soft collar – allowing 96% of N neck flexion and 73% extension Hard collar – allow 72-73% of N flexion and extension Combination of b/l sand bag secured with 3 inch tape and philadelphia collar is most effective pre-hospital stability collar allowing for almost no flexion although 35%extension is possible

Cervical Spine Immobilization Using Cervical Collar, Head Tape and Sand Bags

Spine imaging Asymptomatic Patient  Option - Xray not needed in alert, sober, compliant patient without neck pain and tenderness or major distracting injuries Symptomatic Patient  Standard – Ap, lat and odontoid view  Lateral cervical spine view must include base of occiput and top of first thoracic vertebra  Ap view must include spinous process of all cervical vertebra from C2 to T1  Open mouth view should visualise lateral masses C1 & odontoid peg  Intubated unconscious pt.: lateral cx spine film, A-P, & CT scan of occiput – C3

CT myelogram – Bony detail of fracture site, and anatomic relation of segment to spinal cord. MRI – anterior discs, ligamentum flava & cord contusion.

Cervical trauma- Clinicopathologic considerations Respiratory consequences : Major cause of death. Respiratory failure due to paralysis of respiratory muscles. Above C4 – diaphragmatic respiration is lost Below C4 – Intercostal muscles paralysis. Pulmonary oedema  Neurogenic associated with head injury.  Iatrogenic – Inadvertent fluid administration to combat spinal shock.

Cervical trauma- Clinicopathologic considerations-contd Cardiovascular & neurogenic response. a)Bradycardia and hypotension. b)Cardiac irregularities. c)Autonomic dysreflexia. d)Spinal shock → decreased spinal cord perfusion → spinal cord ischemia. Temperature control → Hypothermia.

Anaesthetic considerations Almost all the procedures will require general anaesthesia because of the constraints of airway management, positioning and duration of surgery.

Anaesthetic considerations  Patients medical history and physical examination.  Pre medication and patient education.  Airway management  Positioning.  Intraoperative monitoring.  Special intra op requirements like wake up test, SSEP, MEP  Fluid requirement.  Extubation.  Post op complications.

Airway evaluation Should be evaluated in the same manner as for any patient with particular attention to a) range of motion to head and neck. b) presence of any neurological symptoms during neck movement c) problems regarding instability, need for awake intubation and preoperative external stabilisation should be reviewed.

Airway problems a) atlantoaxial subluxation, b) traumatic spinal cord injury combined with facial trauma, c) spinal deformity, d) rheumatoid arthritis e) limited movement at atlantooccipital joint and c 1,c 2 joint

Systematic considerations for patients undergoing cervical spine surgeries Respiratory * Reduction in total lung capacity and vital capacity *Increased VQ mismatch Cardiac *Congenital cardiac lesions, pericardial effusion,conduction abnormality *Hypotension, spinal shock Higher in upper cervical lesions especially trauma Pneumonia due to atelectasis and retained secretions, hypoxia. Congenital cervical diseases, rheumatoid arthritis Spinal cord injury, (acute and chronic)

Neurological Preexisting neurological deficit Musculoskeletal Muscular Dystrophy Respiratory impairment Nutrition Malnutrition Careful preoperative documentation Abnormal response to muscle relaxants Postoperative ventilation may be required Likely in metastatic carcinoma and spinal cord trauma

Patient education and premedication Regarding the anaesthetic procedures Awake intubation if planned Intraop wake up test Postoperative ventilatory support when likely Premedication may be needed to reduce the level of anxiety. Gastric prokinetics and antisialogogues to be given for awake intubation

Airway Management- Cautions for success a)Awareness of the risk of spinal cord injury during laryngoscopy. b)Recognition of increased risk of encountering the difficult airway. c)Attention to minimise the motion of cervical spine.

Airway Management--The ideal technique In emergency - Direct laryngoscopy with stabilization of cervical spine with rigid collar or MILS Elective- Awake fiberoptic intubation Advantages of awake intubation a)Maintenance of normal muscle tone which has been suggested to splint an unstable spinal column. b)Ability to perform neurological examination following intubation and positioning Disadvantages a)Stressful b)Requires cooperation of the patient c)Prolonged duration

Manual inline stabilisation of cervical spine

Awake Fiberoptic intubation Position, Secretions, Sedation Nasal- anesthetized and vasoconstricted xylometazoline and 4% lignocaine Oral and Tracheal Anesthesia 10% lignocaine spray or viscous lignocaine/ 4% lignocaine with atomizer. Transtracheal Block- identifying and penetrating cricothyroid membrane while neck is extended 4 ml of 4% lignocaine SLN block (b/l)- hyoid bone located and 3 ml 2% lignocaine infilterated 1cm below each greater cornu

Awake Fiberoptic intubation

Awake Fibreoptic intubation

In cervical trauma Assess Airway and Oxygenation Apnoea/ Resp. Distress Emergency Airway Intubation-MILS without axial traction Airway Secured YesNo Radiological spine evaluation Mask / LMA ventilation oral nasal airway Adequate Elective Airway C Spine X-ray (lat,A-P, open mouth) CTScan*, MRI Results NormalAbnormal Caution oral nasal intubation Awake fibre optic intubation surgical airway

Comparison of different techniques of intubation for cervical spine (summary of various published studies) TechniqueC-Spine Motion Intubation Difficulty Req time Fibreoptic 0↑ ↑ Blind Nasal ↓↑↑ Rigid Collar ↓↑↑ MIL stabilization ↓↑↑ Bullard/ conventional ↓↓↑ McCoy/ conventional ↓↑↑ Lighted stylet / fibreoptic 0-↑↑ ILMA/fibreoptic 0↑↑

Positioning Positioning of patients with cervical spine disease may be associated with risk of neurological injury. It is safe to perform an awake intubation followed immediately by positioning before general anaesthesia is induced. Prolonged procedures therefore-avoid compression or stretching of peripheral nerves /vasculature or entrapment of digits (provide liberal padding ).

Various positions a) Prone b) Supine c) Sitting (obsolete)

PRONE POSITION MOST COMMONLY USED

Anesthetic problems of the prone position Airway: ET tube kinking or dislodgement Edema of upper airway in prolonged cases Blood Vessels: Arterial or venous occlusion of the upper extremity Kinking of femoral vein with marked flexion of the hips  abdominal pressure:  epidural venous pressure  bleeding Nerves: Brachial plexus stretch or compression Ulnar N compression: pressure to the olecranon Peroneal N compression: pressure over the head of the fibula Lateral femoral cutaneous N trauma: pressure over the iliac crest Head and Neck: Gross hyperflexion or hyperextension of the neck External pressure over the eyes: retinal injury Lack of lubrication or coverage of eyes: corneal abrasion Headrest may cause pressure injury of supraorbital N. Excessive rotation of the neck: brachial plexus problems kinking of the vertebral artery L-spine excessive lordosis may lead to neurologic injury

Monitoring Physiological Pulse oximetry Continuous ECG monitoring EtCo2 CVP Temperature Urine output Invasive BP Swan Ganz catheter? Neurological Wake up test SSEP Transcutaneus MEP

wake up test Evaluates gross functional integrity of motor pathway. Patient is lightened from anaesthesia to a plane where he can follow simple commands Advantage No special equipment is required Disadvantage Intermittent monitor Patient discomfort and Increased blood loss Overzealous movement can dislodge monitors and vascular lines

SSEP It is a sensory evoked response in which peripheral sensory nerves are stimulated electrically and the response is measured along the sensory pathway over the somatosensory cortex. The large mixed motor and sensory nerves are stimulated, median nerve and ulnar nerve in the cubital fossa, common peroneal and posterior tibial nerve in popliteal fossa Injury or compromise of neurological pathways may be seen as an increase in the latency or decrease in the amplitude of the waveforms. These potentials may also be affected by inhalational agents, bolus IV anaesthetic agents, ischemia, hypoxia, hypotension, anemia, hypercapnia

SSEPs provides an indirect way of monitoring adjacent motor pathways because more acute impairment affects function of many adjacent pathways, not just the posterior column. However, this cannot be guaranteed. The blood supply of the corticospinal motor tracts differs from that of the dorsomedial sensory tracts. It is possible to have normal SSEPs recordings throughout surgery, but to have a paraplegic patient postoperatively. Typical tracing and L-10

MEPs Functional integrity of motor tract is evaluated by this monitor. These are electrical impulses measured in the peripheral nerves and muscles in response to stimulation of cortex or spinal cord They are particularly important during spinal surgery for vascular malformations and spinal cord tumors in which injury is highly localized and missed by other techniques. They are earlier predictors of any impending damage.

Maintenance of anaesthesia Altered pharmacokinetics due to 1.Muscle wasting 2.Increased volume of distribution 3.Decreased serum albumin 4.Proliferation of extrajunctional receptors Nitrous oxide, narcotics, propofol with or without inhalational agent Muscle relaxants are used at the discretion of the anaesthesiologists in collaboration with the surgeon and the neurologist

Fluid management Balance between maintaining vascular volume to ensure an adequate blood pressure for perfusion of vital organs, including the spinal cord and avoiding venous congestion that may occur in fluid overload. Crystalloids and colloids can be used. Dextrose containing fluids are to be avoided because of the risk of worsening neurological outcome in the presence of hyperglycemia during spinal cord ischemia. Deliberate or induced hypotension is used to reduce blood loss, to provide a blood less surgical field. The desired drop depends on the patient’s medical condition

Extubation Extubation is usually performed in the operating room immediately following surgical procedures. Postoperative ventilation may be required for patients with 1.Pre op pulmonary dysfunction 2.High cervical cord surgery 3.Hemodynamic instability 4.Prolonged procedure with massive fluid shift 5.Any case of expected difficult reintubation- a conservative approach to extubation is required. (Use of cook’s airway exchange catheter)

Perioperative complications of cervical spine surgery a)Airway obstruction : edema, hematoma,recurrent laryngeal nerve palsy. b)Respiratory: motor paralysis and infection (pneumonia). c)Cardiovascular: hypotension, bradycardia, arrhythmias, hypertension ( spinal cord injury, carotid sinus stimulation). d)Neurological: Injury to nerve roots – as a result of direct surgical manipulation Injury to lower cranial nerves – VII, IX, X, XII Injury to peripheral nerves - as a result of positioning Injury to spinal cord.

e) Vessel injury – vertebral and carotid artery during dissection f) Tracheal and oesophageal injury g) CSF leaks - due to tear of dural and arachnoid membranes can lead to meningitis, pseudomeningocoele, permanent CSF fistula h) DVT – seen in 30% of neurosurgical patients, especially those who had been paraplegic. Pulmonary embolism may occur

Risk of spinal cord damage Risk of damage depends upon a)Length and type of surgical procedure –removal of intramedullary tumours b)Spinal cord perfusion pressure – vascular compromise c)Pressure on neural tissue during surgery - mechanical compression, direct injury due to instrumentation Risk can be minimized by a)Careful positioning b)Maintenance of SCPP c)Drugs : methylprednisolone within 8 hours after insult

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