9.4 Spinal cord and peripheral nerve disorders

The spinal cord and peripheral nervous system are crucial for transmitting signals between the brain and body. These structures enable sensory perception, motor control, and autonomic functions. Understanding their anatomy and physiology is essential for grasping how neurological disorders can impact various bodily functions.

Spinal cord and peripheral nerve disorders can have profound effects on a person's mobility, sensation, and independence. From traumatic injuries to autoimmune conditions, these disorders require comprehensive assessment and management. Rehabilitation plays a vital role in maximizing function and quality of life for those affected.

Spinal Cord and Peripheral Nervous System Anatomy and Physiology

Anatomy of spinal cord and PNS

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• Spinal cord anatomy
  • Extends from brainstem to lumbar region (L1-L2) measures about 45 cm long in adults
  • Divided into cervical (C1-C8), thoracic (T1-T12), lumbar (L1-L5), and sacral (S1-S5) segments based on spinal nerve roots
  • Contains ascending sensory tracts (spinothalamic, dorsal columns) transmit information about pain, temperature, touch, and proprioception
  • Contains descending motor tracts (corticospinal, rubrospinal) control voluntary movements and modulate reflexes
• Peripheral nervous system (PNS) anatomy
  • Consists of 31 pairs of spinal nerves and 12 pairs of cranial nerves that extend from spinal cord and brainstem to rest of body
  • Includes sensory (afferent) nerves detect stimuli from receptors (mechanoreceptors, nociceptors, thermoreceptors) in skin, muscles, and organs
  • Includes motor (efferent) nerves innervate skeletal muscles (somatic nervous system) and smooth muscles, cardiac muscle, and glands (autonomic nervous system)
  • Sensory nerves enter dorsal root ganglia and synapse in spinal cord gray matter
  • Motor nerves exit ventral horn of spinal cord gray matter and innervate effector tissues
• Spinal cord and PNS physiology
  • Spinal cord acts as conduit for bidirectional flow of sensory and motor information between brain and body
  • PNS nerves facilitate communication between spinal cord and peripheral tissues via action potentials and neurotransmitters (acetylcholine, norepinephrine)
  • Reflexes (stretch reflex, withdrawal reflex) mediated by spinal cord circuits provide rapid responses to stimuli without brain involvement
• Damage to spinal cord and PNS
  • Trauma (spinal cord injury, nerve compression), inflammation (multiple sclerosis, Guillain-Barré syndrome), infection (polio, herpes zoster), or degeneration (amyotrophic lateral sclerosis, diabetic neuropathy) can lead to various disorders
  • Spinal cord damage can cause paralysis, sensory loss, and autonomic dysfunction (bladder/bowel incontinence, orthostatic hypotension) below level of injury
  • PNS damage can lead to sensory deficits (numbness, paresthesia), muscle weakness, and altered reflexes (hyporeflexia, areflexia) in affected dermatomes and myotomes

Common Spinal Cord and Peripheral Nerve Disorders

Spinal cord disorders: causes and management

• Spinal cord injury (SCI)
  • Causes: trauma from falls, motor vehicle accidents, sports injuries (diving, football), or violence (gunshot wounds) can compress or transect spinal cord
  • Clinical manifestations: paralysis (paraplegia, tetraplegia), sensory loss, autonomic dysfunction, and complications (pressure ulcers, urinary tract infections, spasticity, neuropathic pain)
  • Management: immobilization (cervical collar, backboard), surgery (decompression, stabilization), rehabilitation (physical therapy, occupational therapy), and symptom management (medications, catheterization, bowel program)
• Spina bifida
  • Causes: congenital neural tube defect due to genetic and environmental factors (folate deficiency) leads to incomplete closure of spinal column and meninges
  • Clinical manifestations: varying degrees of paralysis, sensory deficits, and bowel/bladder dysfunction depending on level and severity of lesion (occulta, meningocele, myelomeningocele)
  • Management: surgery (closure of defect, shunting for hydrocephalus), rehabilitation, and lifelong multidisciplinary care (orthopedics, urology, neurosurgery, physical medicine)
• Multiple sclerosis (MS)
  • Causes: autoimmune disorder causing inflammation and demyelination of CNS nerve fibers, possibly triggered by viral infection or environmental factors in genetically susceptible individuals
  • Clinical manifestations: vision problems (optic neuritis), muscle weakness, coordination issues (ataxia), sensory disturbances (paresthesia), and fatigue, with relapsing-remitting or progressive course
  • Management: disease-modifying therapies (interferon beta, glatiramer acetate, monoclonal antibodies), symptom management (medications for spasticity, pain, bladder dysfunction), and rehabilitation (exercise, assistive devices)

Peripheral nerve disorders: assessment and care

• Guillain-Barré syndrome (GBS)
  • Assessment: progressive ascending muscle weakness, reduced or absent reflexes, and sensory changes (paresthesia, numbness), with possible autonomic dysfunction (labile blood pressure, arrhythmias)
  • Nursing interventions: monitor respiratory function (vital capacity, negative inspiratory force), prevent complications (positioning, range of motion, DVT prophylaxis), and provide supportive care (pain management, emotional support)
• Diabetic neuropathy
  • Assessment: sensory deficits (reduced sensation to light touch, vibration, temperature), pain (burning, tingling), muscle weakness (atrophy, reduced strength), and autonomic dysfunction (gastroparesis, orthostatic hypotension, erectile dysfunction)
  • Nursing interventions: blood glucose control (medication adherence, diet, exercise), foot care (daily inspection, proper footwear, prompt treatment of injuries), pain management (gabapentin, pregabalin, TCAs), and patient education on preventing complications (falls, skin breakdown, infections)

Rehabilitation for neurological disorders

• Assess patient's functional status using standardized tools (FIM, ASIA impairment scale) and set realistic goals based on level of injury, age, and pre-morbid function
• Collaborate with multidisciplinary team, including physiatrists, physical therapists, occupational therapists, speech-language pathologists, and social workers, to develop comprehensive rehabilitation plan
• Implement interventions to:
  1. Maintain range of motion and prevent contractures through stretching, positioning, and splinting
  2. Strengthen unaffected muscles and promote neuroplasticity through exercises (resistance training, functional electrical stimulation)
  3. Manage pain and other symptoms using medications, modalities (heat, cold, TENS), and relaxation techniques
  4. Prevent complications such as pressure ulcers (frequent turning, pressure-redistributing surfaces), urinary tract infections (catheter care, bladder training), and deep vein thrombosis (compression stockings, anticoagulants)
• Provide adaptive equipment (wheelchairs, braces, reachers) and assistive devices (communication aids, environmental controls) to maximize independence in activities of daily living and mobility
• Educate patients and caregivers on self-care (bathing, dressing, toileting), medication management (dosing, side effects, interactions), and home safety (fall prevention, emergency preparedness)
• Address psychosocial needs by providing emotional support, counseling, and referrals to support groups and community resources
• Regularly reassess progress using objective measures and adjust rehabilitation plan as needed to optimize outcomes and quality of life