Spinal Cord Injuries and Lesions

Spinal Cord Injuries

Spinal Cord Lesions

• Deficits characteristic of spinal cord lesions discussed include lesions of the anterior, lateral, and posterior column, as well as anterior spinal cord syndrome, syringomyelia, and Brown-Séquard syndrome

Ascending Tracts

• Clinically important ascending tracts and where they cross over are important details

Descending Tracts

• Clinically important descending tracts and where they cross over are important details

Spinal Cord End

• The level at which the spinal cord ends is also an important detail

Basic Features of Spinal Cord Disease

• UMN findings below the lesion such as hyperreflexia and Babinski's sign
• Sensory and motor involvement that localizes to a spinal cord level
• Bowel and Bladder dysfunction is common

UMN vs LMN

• Differences between UMN and LMN, for example, cauda equina vs. myelopathy are useful parameters

Motor Symptoms

• Motor symptoms such as plegia and paresis
• Plegia means complete lesion
• Paresis means some muscle strength is preserved
• Tetraplegia (or quadriplegia) involves injury of the cervical spinal cord
• Patients can still move arms using segments above the injury; a C7 injury patient can still flex his forearms, using the C5 segment
• Paraplegia involves injury of the thoracic or lumbo-sacral cord, or cauda equina
• Hemiplegia involves paralysis of one half of the body, usually in brain injuries like stroke

Motor Symptoms (Paralysis)

• The ASIA motor scoring system for extremities can be a useful tool

Motor Exam

• Strength helps localize the lesion
• Upper cervical lesions can cause quadriplegia with impaired respiration
• Lower cervical lesions have preserved proximal arm strength and hand and leg weakness
• Thoracic lesions may cause paraplegia
• Paraplegia can also be found with a midline lesion in the brain
• Tone is also important, and increases distal to the lesion.

Babinski Sign

• Babinski sign is indicative of UMN syndrome

Sensory Symptoms

• Sensory symptoms like pain, temperature, and proprioception assessment is important

Sensory Exam

• Establishing a sensory level is important
• Nipple sensory level are at T4-5
• Umbilicus sensory level is at T8-9
• Evaluation of posterior columns for vibration and joint position sense (proprioception) should be tested
• Assessment of spinothalamic tracts which detects pain and temperature should be carried out

Spinal Cord Injuries

• Spinal shock causes flaccid paralysis
• Loss of autonomic reflexes if injury above T6
• Bowel & bladder dysfunction is likely

Autonomic Disturbances

• Neurogenic bladder can cause urgency, incontinence, and retention
• Bowel dysfunction often causes constipation
• High cord lesions have loss of blood pressure control
• Alteration in sweating may occur

Ascending and Descending Tracts

• Ascending and descending tracts can be assessed

Central Cord Syndrome

• The image shows the spinal cord regions affected in central cord syndrome
• Anterolateral spinothalamic tracts are affected in small lesions
• Cuneatus fasciculus of the dorsal column and the medial aspect of the lateral corticospinal tracts are affected in larger lesions
• Upper extremities are more affected than the lower extremities
• Thoracic, lumbar, and sacral function is retained
• Bilateral loss of discriminative pain and temperature in the upper extremities and superior portion of the trunk may be seen
• Larger lesions may see loss of discriminative touch and conscious proprioception due to involvement of cuneatus fasciculus and motor impairments due to involvement of lateral corticospinal tracts
• The lesion interrupts fibers crossing to enter the spinothalamic tracts, and fibers mediating the tendon stretch reflex
• As enlargement happens, affects the intermediolateral columns (autonomic function), and the lateral corticospinal tracts

Syringomyelia

• Fluid filled cavitation in the center of the cord
• Cervical cord is the most common site
• Loss of pain and temperature occur early, related to the crossing fibers
• Causes cape-like sensory loss
• Weakness of muscles in arms with atrophy and hyporeflexia (Anterior Horn Cervical)
• Later - CST involvement with brisk reflexes in the legs, spasticity, and weakness
• May occur as a late sequelae to trauma or malformation

Anterior Cord Syndrome

• Image shows spinal cord regions affected in anterior cord syndrome
• Essentially all ascending and descending tracts are involved except those of the dorsal column
• Bilateral loss of discriminative pain and temperature and paralysis below level of lesion occurs
• Proprioception and discriniminative touch remain intact

Spinal Cord Arteries

• Vertebral artery branches join to form the anterior spinal artery
• Descends the anterior median fissure and supplies the anterior two-thirds of the spinal cord
• Each vertebral artery produces a single posterior spinal artery that descends the posterior spinal cord
• Supplies the posterior one-third of the spinal cord
• Posterior spinal arteries can originate from the posterior inferior cerebellar arteries (PICAs)
• Posteromedial spinal arteries can also exist
• The most important radiculomedullary artery is the artery of Adamkiewicz:
• Arises from T9 to T12, most commonly, but can originate anywhere from T8 to L3
• Most commonly originates from the left side
• Injury to this artery can lead to paraplegia

Brown-Sequard Syndrome

• All ascending and descending tracts on one side of the spinal cord are affected
• Involvement of the Dorsal Column causes a loss of proprioception and discriminative touch ipsilaterally (below the lesion)
• Involvement of the Anteriolateral Spinothalamic tract causes a loss of crude touch and discriminative pain and temperature on the contralateral side a few levels below the lesion
• The difference in affected level is due to the fact that the anteriolateral spinothalamic tracts ascend ipsilaterally several segments before decussating
• Involvement of the descending tracts causes paralysis ipsilaterally below the level of the lesion
• Spinal cord hemisection
• Can be caused by trauma or tumor
• Dissociated sensory loss occurs as a result -loss of vibration/proprioception ipsilateral to the lesion, these pathways cross at the level of the brainstem