Spinal Cord Lesions Overview

Study Notes

Fibers in the anterolateral pathways cross over to the opposite side of the spinal cord, affecting contralateral pain and temperature sensation starting a few spinal segments below the lesion.
The anterolateral pathways are organized somatotopically in the spinal cord, with the feet represented most laterally. This organization is maintained through the brainstem as well.
There are three tracts in the anterolateral pathways: spinothalamic, spinoreticular, and spinomesencephalic.
The spinothalamic tract is the main pathway for discriminative pain and temperature sensation. It relays information to the ventral posterior lateral nucleus (VPL) of the thalamus.
Spinal cord lesions are a common cause of disability, affecting motor, sensory, and autonomic pathways.
Common causes of spinal cord dysfunction:
- Extrinsic compression from degenerative spine disease, trauma, or cancer
- Central cord syndrome:
  - Due to spinal cord contusion, syringomyelia, or intrinsic tumors like hemangioblastoma, ependymoma, or astrocytoma.
  - Affects motor and sensory function below the level of the lesion, with near complete loss of pain and temperature sensation below the lesion except for a region of sacral sparing.
- Posterior cord syndrome:
  - Due to trauma, extrinsic compression, multiple sclerosis, vitamin B12 deficiency, or tabes dorsalis.
  - Affects vibration and position sense below the level of the lesion.

Posterior column–medial lemniscal pathway lesions often cause tingling, numbness, a tight band-like sensation, or a gauze-like sensation on the fingers.
Anterolateral pathway lesions often cause sharp, burning, or searing pain.
Parietal lobe or primary sensory cortex lesions can cause contralateral numbness and tingling, but pain can also be prominent.
Thalamic lesions can cause severe contralateral pain, called Dejerine–Roussy syndrome.
Cervical spine lesions can cause Lhermitte’s sign, an electricity-like sensation running down the back with neck flexion.
Nerve root lesions can cause radicular pain that radiates down a limb, accompanied by numbness and tingling, and is provoked by movements that stretch the nerve root.
Peripheral nerve lesions, similarly, often cause pain, numbness, and tingling in the sensory distribution of the nerve.
Common terms for sensory abnormalities:
- Dysesthesia (unpleasant, abnormal sensation)
- Allodynia (pain from normally non-painful stimuli)
- Hyperpathia or hyperalgesia (enhanced pain to normally painful stimuli)
- Hypesthesia (decreased sensation)

Bladder function is under voluntary control in healthy adults.
The detrusor reflex is mediated by intrinsic spinal cord circuits and regulated by the pontine micturition center, cerebellum, and basal ganglia.
Bladder emptying is initiated by voluntary relaxation of the external urethral sphincter.
Lesions affecting bilateral medial frontal micturition centers result in bladder incontinence, but urine flow and emptying are normal.
Common causes of incontinence include hydrocephalus, meningioma, glioblastoma, traumatic brain injury, and neurodegenerative disorders.