Blood supply Two posterior spinal arteries Anterior spinal artery – formed by the confluence of two vertebral arteries The lower cervical cord is a region of relative ischemia and is vulnerable for ischemic injury should the anterior spinal artery be compromised between the foramen magnum and C 8, the cervical watershed.
Spinal Cord Paralysis Levels C1-C3 All daily functions must be totally assisted Breathing is dependant on a ventilator Motorised wheelchair controlled by sip and puff or chin movements is required C4 Same as C1-C3 except breathing can be done without a ventilator C5 Good head, neck, shoulder movements, as well as elbow flexion Electric wheelchair, or manual for short distances
C6 Wrist extension movements are good Assistance needed for dressing, and transitions from bed to chair and car may also need assistance C7-C8 All hand movements Ability to dress, eat, drive, do transfers, and do upper body washes T1-T4 (paraplegia) Normal communication skills Help may only be needed for heavy household work or loading wheelchair into car
T5-T9 Manual wheelchair for everyday living Independent for personal care T10-L1 Partial paralysis of lower body L2-S5 Some knee, hip and foot movements with possible slow difficult walking with assistance or aids Only heavy home maintenance and hard cleaning will need assistance
Treatment of Spinal Injuries No Current Effective Treatment Prevention is Key – all current medical and surgical treatments aimed to prevent further injury to the spinal cord.
Spinal Cord Injuries May occur with neck or back trauma Associated with blunt head trauma, especially when casualty is unconscious Can occur with penetrating trauma of vertebral column Improper handling may cause further injury
Pathophysiology Damage – Begins centrally in grey matter and spreads centrifugally. Primary insult –B/W Time of injury and initial care Secondary insult – Delayed swelling Continued mechanical trauma Low perfusion Endogenous factors Initial segmental loss can be withstood because only small portion of grey matter neuronal pool is involved.
– ASIA A: Complete: no motor or sensory function is preserved in the sacral segments S4-S5 – ASIA B: Incomplete: sensory but NOT motor function is preserved below the neurological level and includes the sacral segments – ASIA C: Incomplete: motor function is preserved below the neurological level and more than half of key muscles below the neurological level have a muscle grade <3 – ASIA D: Incomplete: motor function is preserved w/ muscle grade > 3 – ASIA E: Normal
Diagnosis and management of acute spinal cord injury Initial assessment and immobilization Resuscitation and medical management Radiological diagnostics Anaesthesia management Surgical therapy Post op critical care management
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
Secure casualty to long spine board with straps across forehead, chest, hips, thighs, and lower legs
Resuscitation and medical management ATLS principles Airway Breathing Circulatory Neurologic Classification Spinal Imaging GastroIntestinal System Genitourinary System Skin
Airway Risk Associated with Level of Injury Decision to Intubate Airway Intervention
Risk Associated with Level of Injury cont’d Ventilatory Function – C1 - C7 = accessory muscles – C3 - C5 = diaphragm “C3-4-5 keeps the diaphragm alive! – T1 - T11 = intercostals – T6 - L1 = abdominals
Decision to Intubate: Need for Artificial Airway is Usually Related to Resp Compromise e.g. – Loss of innervation of the diaphragm (C 3-4-5 keep the diaphragm alive) – Fatigue of innervated resp muscles – Hypoventilation – SaO2 45 – V/Q mismatch – PaO2/FiO2 <250 – Secretion retention – Atelectasis
Decision to Intubate Related to Neurological Level Occiput - C3 Injuries (ASIA A & B) – Require immediate intubation and ventilation due to loss of innervation of diaphragm
Decision to Intubate Related to Neurological Level cont’d C4-C6 Injuries (ASIA A & B) – Serious consideration for prophylactic intubation and ventilation if: Ascending injury (requires serial M/S assessment by a trained clinician) Fatigue of unassisted diaphragm Inability to clear secretions
Airway Intervention Maintaining Spinal Precautions – Supine position Maintain neutral C-spine – Remove rigid collar and sandbags – Manually stabilize C-spine 2 person technique: – 1st person to provide manual in-line stabilization (not traction) of C- spine – 2nd person intubates
Circulatory Spinal Shock Temporary suppression of all reflex activity below the level of injury Occurs immediately after injury Intensity & duration vary with the level & degree of injury Neurogenic Shock The body’s response to the sudden loss of sympathetic control Distributive shock Occurs in people who have SCI above T6 (> 50% loss of sympathetic innervation )
Hemodynamic Instability: Intervention First Line: Volume |Resuscitation (1-2 L) Second line: Vasopressors- (dopamine/norepinephrine) to counter loss of sympathetic tone and provide chronotropic support to the heart
Hemodynamics and Cord Perfusion Options: – Avoid hypotension – Maintain MAP 85-90mmHg for first 7 days if possible
Bradycardia: Intervention Prevention: – Avoid vagal stimulation – Hyperventilate and hyperoxygenate prior to suctioning – Pre-medicate patients with known hypersensitivity to vagal stimuli Treatment of Symptomatic Bradycardia: – Atropine 0.5 - 1.0 mg IV
Neurological Classification – Motor and sensory assessment – ASIA Impairment Scale (A-E) – Clinical Syndromes (patterns of incomplete injury)
Spinal Shock An immediate loss of reflex function, called areflexia, below the level of injury Signs: – Slow heart rate – Low blood pressure – Flaccid paralysis of skeletal muscles – Loss of somatic sensations – Urinary bladder dysfunction Spinal shock may begin within an hour after injury and last from several minutes to several months, after which reflex activity gradually returns
Central Cord Syndrome Usually involves a cervical lesion May result from cervical hyperextension causing ischemic injury to the central part of the cord Motor weakness is more present in the upper limbs then the lower limbs Patient is more likely to lose pain and temperature sensation than proprioception Patient may complain of a burning feeling in the upper limbs More commonly seen in older patients with cervical arthritis or narrowing of the spinal cord
Brown-Sequard Syndrome Results from an injury to only half of the spinal cord and is most noticed in the cervical region Often caused by spinal cord tumours, trauma, or inflammation Motor loss is evident on the same side as the injury to the spinal cord Sensory loss is evident on the opposite side of the injury location (pain and temperature loss) Bowel and bladder functions are usually normal Person is normally able to walk although some bracing or stability devices may be required
Anterior Spinal Cord Syndrome Usually results from compression of the artery that runs along the front of the spinal cord Compression of SC may be from bone fragments or a large disc herniation Patients with anterior spinal cord syndrome have a variable amount of motor function below the level of injury Sensation to pain and temperature are lost while sensitivity to vibration and proprioception are preserved
Cauda Equina Syndrome: Injury to the lumbosacral nerve roots w/ in the neurocanal resulting in areflexive bladder, bowel and lower limbs
Spine Imaging the 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 – Option – discontinue protection after…. normal and adequate dynamic radiography, or normal MRI within 48hrs of injury, or at the discretion of treating MD
CT myelogram – Bony detail of fracture site, and anatomic relation of segment to spinal cord. MRI – anterior discs, ligamentum flava & cord contusion.
GI System Risk of aspiration is high d/t: – cervical immobilization – local cervical soft tissue swelling – delayed gastric emptying Parasympathetic reflex activity is altered, resulting in: – decreased gut motility and – often prolonged paralytic ileus
GI Intervention- Nasogastric tube IV H2 blockers GU Intervention – Catheterisation Skin Intervention – *Remove spine board *Turn or reposition individuals with SCI initially every 2 hours in the acute phase if the medical condition allows.
Pharmacologic Therapy Methylprednisolone-controversial – 30mg/kg IV loading dose + 5.4 mg/kg/hr (over 23hrs) effective if administered within 8 hours of injury – If initiated < 3hrs continue for 24 hrs, if 3-8 hrs after injury, continue for 48hrs (morbidity higher - increased sepsis and pneumonia) Thromboprophylaxis - LMWH, discontinued at 3months
Secondary Interventions Without mechanical compression on CT myelogram – External stabilisation Mean arterial pressures are kept b/w 80-90 mmHg and CO kept ( N/ high N ) Dopamine infusion may be necessary
Anaesthesia Management Pre op assessment Medical history Premedication and pt. Education Airway management Positioning Fluid requirements Special intraop requirements(wake up test) Post op pain and pulmonary toilet
Airway evaluation MP classification and range of neck mobility and elicitation of pain/ neurological symptom Pulmonary evaluation During spinal shock (3 days – 6 wks) ABG- assess adequacy of ventilation, intubation if hypoxemia or hypercapnia (on O2 mask) Chronic stage PFT and Chest X ray – Restrictive pattern (FEV1&FVC)
Severity of functional impairment related to – Angle of scoliosis, No of vertebrae, cephalad location of curve and loss of normal kyphosis. Respiratory function should be optimised – Treating infection Bronchodilation Chest physiotherapy
Cardiac evaluation ECG – myocardial ischemia Cardiovascular instability evidenced by hypotension, hypertension, brady & arry. – assessment of cardiac reserve and to optimise circulatory volume according to cardiac function and peri. Vas. Tone. Pacemaker – persistently bardycardic. High spinal cord injury – initially spinal shock,autonomic dys,impaired LVF and later autonomic dysreflexia.
Neurological evaluation Document preexisting deficits Neurological dys may dictate intubation tech,monitoring and choice of agents. Pharmacology Altered P/K because of muscle wasting,inc volume of distribution,dec serum albumin
Preop preparation Hb, Hct, WBC and urinalysis Other tests indicated by history SE, BUN, Creatinine, PT,aPTT, Platelet count, ECG, Chest radiograph, ABG and PFT. Echo – to assess LV function pulmonary artery pressures and stress echo in sedentary patients
Premedication If anxious IV midazolam Under supervision Atropine if HR < 70 – Dose 0.04mg/kg H2 receptor blocker/ PPI Induction Unnecessary/ contraindicated for unconscious, recently injured patients with spinal cord trauma / those with severe shock.
Technique of intubation Elective - fiberoptic intubation Emergency – MILS with rapid sequence Maintenance Nitrous oxide, inhalation agent
Positioning Goals Adequate surgical exposure Anatomic position of extremities & head Avoid abdominal pressure Adequate padding Various positions a) Prone b) Supine c) Sitting (obsolete
PRONE POSITION MOST COMMONLY USED EYES: Corneal abrasion Optic neuropathy Retinal artery occlusion HEAD & NECK Venous and lymphatic obstuction ABDOMEN Impaired ventilation Decreased CO
Monitoring Neurological Wake up test SSEP Transcutaneus MEP Physiological Pulse oximetry Continuous ECG monitoring EtCo2 CVP Temperature Urine output Invasive BP Swan Ganz catheter?
Post operative pain relief NSAIDS (IM,IV,P/R) IV opiods (Intermitent / continuous infusion ) PCA
Post op critical care management Indications for post op ventilation – Preexisting NM disorder Severe restrictive – VC <35% Obesity / RVF Prolonged surgery Surgical invasion of thoracic cavity Blood loss > 30ml/kg
post op contd Prepare for weaning Adequate nutrition and metabolic state Infection – May be masked(Poikilothermia) Optimal fluid management Treat mechanical impairment to breathing like abd distention, tight halo cast, position Psychological preperation
Post op contd Chest Physiotherapy – Postural drainage, chest wall percussion and vibration, tracheal suctioning and breathing exercises. Cough – Glossopharyngeal breathing and huffing. Breathing exercises
Perioperative complications of 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
Outcome Acute spinal injury who survive >24hrs,85%alive at 10years Most common causes of death-pneumonia, non-ischemic heart disease (occult autonomic dysfn), suicide (lifelong impact of injury) www.anaesthesia.co.inwww.anaesthesia.co.in firstname.lastname@example.org@gmail.com