What is the management and prognosis of reflexes in patients with spinal shock?

Management and Prognosis of Reflexes in Spinal Shock

In patients with spinal shock, a systematic approach to reflex assessment and management is essential, with early tracheostomy recommended within the first 7 days for patients with upper cervical spinal cord injuries (C2-C5) to improve respiratory outcomes and neurological recovery.1

Understanding Spinal Shock

Spinal shock is characterized by the sudden loss of sensory, motor, and reflex function below the level of spinal cord injury. Key features include:

• Complete loss of reflexes below the level of injury, though studies show less than 8% of patients have truly absent reflexes on the day of injury 2
• Duration varies between patients, with some symptoms persisting up to 12 weeks 3
• Hyperpolarization of caudal motoneurons is a major physiological derangement in spinal shock 4

Reflex Evolution During Spinal Shock

The pattern of reflex recovery follows a specific sequence:

• The delayed plantar response (DPR) is typically the first reflex to recover, followed by the bulbocavernosus reflex and cremasteric reflex within the first few days 2
• Deep tendon reflexes (ankle jerk and knee jerk) typically recover later, around 1-2 weeks post-injury 2
• H-reflexes are absent or markedly suppressed within 24 hours of injury but recover to normal amplitudes within several days despite the absence of F-waves 4
• Stretch reflexes are proportionally more depressed than H-reflexes, consistent with depressed fusimotor drive after spinal cord injury 4

Prognostic Value of Reflexes

• Patients with a delayed plantar response (DPR) lasting 2 days or longer were consistently non-ambulatory at discharge 2
• Ambulatory patients either had no DPR or had a DPR of only 1 day's duration 2
• H-reflexes are typically elicitable for days or weeks before clinical reflexes develop 4
• The traditional view of spinal shock based solely on absence of reflexes has limited clinical utility for prognosis 2

Management Recommendations

Respiratory Management

• For patients with cervical spinal cord injuries, implement a bundle approach to facilitate respiratory management:

  • Use abdominal contention belts during periods of spontaneous breathing 1
  • Provide active physiotherapy and mechanically-assisted insufflation/exsufflation devices to remove bronchial secretions 1, 5
  • Administer aerosol therapy combining beta-2 mimetics and anticholinergics 1, 5

• Early tracheostomy is recommended:

  • Within the first 7 days for patients with upper cervical spinal cord injuries (C2-C5) 1
  • After one or more tracheal extubation failures for patients with lower cervical injuries (C6-C7) 1
  • When residual vital capacity is decreased (often reduced by more than 50% in upper level injuries) 1

Blood Pressure Management

• Maintain mean arterial pressure (MAP) up to 70 mmHg during the first week to limit the risk of worsening neurological deficit 1
• Continuously monitor MAP with an arterial catheter as it can be difficult to maintain target MAP levels 1
• Avoid hypotension (systolic BP < 110 mmHg) as it is associated with increased mortality in spinal cord injury patients 1

Neurological Assessment

• Perform serial neurological examinations including mental status assessment, brainstem reflexes, and motor examination 1
• When assessing for brain death or severe neurological injury, be aware that spinally mediated reflexes may be present despite severe brain injury 1
• The clinical differentiation of spinal responses from retained motor responses associated with brain activity requires expertise 1

Underlying Mechanisms and Recovery

• Recovery of reflexes may be related to up-regulation of receptors, resulting in increased sensitivity to neurotransmitters at surviving synapses 6
• Enhanced transmission at Ia fiber-motoneuron connections below the spinal cord injury contributes to the rise in H-reflex amplitude despite persistent hyperpolarization 4
• Non-synaptic transmission and receptor plasticity may play important roles in reflex recovery 6

Rehabilitation Considerations

• Early mobilization should be implemented as soon as the spine is stabilized to prevent pressure ulcers 1
• Stretching techniques should be performed for at least 20 minutes per zone to prevent vicious attitudes, though their effectiveness is not fully demonstrated 1
• Simple posture orthoses and proper bed/chair positioning are important to correct and prevent predictable deformities 1

By understanding the pattern of reflex evolution during spinal shock and implementing appropriate management strategies, clinicians can optimize outcomes for patients with spinal cord injuries.