Spinal Cord Syndromes and Tracts

Spinothalamic Tract

• Responsible for transmitting pain, temperature, and crude touch sensations to the brain
• Composed of the lateral spinothalamic tract (pain and temperature) and the anterior (or ventral) spinothalamic tract (crude touch and pressure)
• Primary sensory neurons synapse in the dorsal horn after entering the spinal cord
• Second-order neurons cross the midline and ascend in the anterolateral aspect of the spinal cord
• Projects to the thalamus, which relays the information to the sensory cortex
• Lesions result in contralateral loss of pain and temperature sensation, typically beginning one to two segments below the lesion

Central Cord Syndrome

• Characterized by greater weakness in the upper extremities than in the lower extremities
• Often results from hyperextension injuries in older individuals with pre-existing cervical spondylosis
• Damage to the central part of the spinal cord affects spinothalamic tract fibers that decussate at that level
• Symptoms: disproportionate motor impairment in the upper extremities, sensory deficits more pronounced in the upper extremities, and varying degrees of bladder dysfunction
• Prognosis varies; many regain the ability to ambulate, but fine motor control in the hands may remain impaired
• Cape distribution of sensory loss is characteristic

Anterior Cord Syndrome

• Results from damage to the anterior two-thirds of the spinal cord
• Typically caused by infarction of the anterior spinal artery or direct trauma
• Characterized by complete motor paralysis below the level of the lesion, loss of pain and temperature sensation, and preservation of proprioception, vibration, and fine touch
• Prognosis for significant motor recovery is generally poor
• Bowel and bladder dysfunction are common due to the involvement of descending autonomic tracts

Anterior Corticospinal Tract

• One of the motor pathways that controls voluntary movement
• Originates in the cerebral cortex, descends through the brainstem, and enters the spinal cord
• Fibers do not decussate in the medulla, descending ipsilaterally in the anterior white matter of the spinal cord
• Fibers decussate at their target spinal segment and synapse with lower motor neurons in the anterior horn
• Primarily controls axial and girdle muscles, contributing to posture and gross motor movements

Dorsal Columns

• Sensory pathways that transmit fine touch, vibration, and proprioception from the periphery to the brain
• Primary sensory neurons ascend ipsilaterally in the dorsal columns (fasciculus gracilis and fasciculus cuneatus) after entering the spinal cord
• The fasciculus gracilis carries information from the lower extremities, while the fasciculus cuneatus carries information from the upper extremities
• Fibers synapse in the medulla at the nucleus gracilis and nucleus cuneatus
• Second-order neurons cross the midline and ascend in the medial lemniscus to the thalamus
• The thalamus relays the information to the sensory cortex
• Lesions result in ipsilateral loss of fine touch, vibration, and proprioception below the level of the lesion

Syringomyelia

• Characterized by the formation of a fluid-filled cavity (syrinx) within the spinal cord
• Most commonly occurs in the cervical region but can extend into the thoracic or lumbar regions
• The syrinx expands, compressing and damaging adjacent neural tissue
• Common causes include Chiari malformation, spinal cord tumors, trauma, and arachnoiditis
• Clinical manifestations vary, but classic findings include: cape-like distribution of sensory loss, muscle weakness and atrophy in the hands and arms, spasticity and hyperreflexia in the lower extremities, and bowel and bladder dysfunction

Brown-Séquard Syndrome

• Results from a hemisection (partial severing) of the spinal cord
• Typically caused by penetrating trauma or spinal cord tumors
• Characterized by: ipsilateral motor paralysis, ipsilateral loss of fine touch, vibration, and proprioception, contralateral loss of pain and temperature sensation (beginning a few segments below the level of the lesion)
• Additional findings include: ipsilateral Horner's syndrome (if the lesion is in the cervical or upper thoracic region) and bowel and bladder dysfunction

Overview of spinal cord tracts like spinothalamic, corticospinal, and dorsal columns. Discusses syndromes including central cord, anterior cord, Brown-Séquard, and syringomyelia. Highlights key neurological conditions and their clinical presentations.