Transverse spinal cord lesion
Impairment of deep sensation (joint-position sense) below the level of the lesion according to the pathway type is always accompanied by muscular hypotonia, loss of tendon reflexes, and the development of sensory ataxia.
In complete transverse spinal cord lesions (most commonly traumatic), spinal shock develops in the acute phase. It manifests as muscular atonia, loss of all modalities of sensation, and impaired pelvic organ function. Later, reflexes return, and the paresis becomes spastic. With gradual compression (e.g., by a tumor), the shock stage is absent, and the paresis is spastic from the outset.
Symptomatology depends on the level:
- High cervical: often leads to a fatal outcome due to paralysis of the diaphragm and intercostal muscles.
- Low cervical: respiratory failure, peripheral paresis of the arms, and spastic paralysis of the legs.
- Thoracic: arm function is preserved, spastic lower paraparesis develops.
- Epiconus (L~IV~ – S~II~): partial paresis of the legs, loss of Achilles reflexes with preserved knee reflexes.
- Conus (from S~III~): movements in the legs are not impaired, reflexes are preserved. Anesthesia of the anogenital region and a peripheral type of pelvic disorders (true urinary and fecal incontinence, absence of the anal reflex, impotence) are typical.
Brown-Séquard syndrome (hemisection)
The clinical picture of a spinal cord hemisection depends on the side and level of the lesion.
On the side of the lesion (ipsilaterally) below the level of the injury, deep sensation is lost and central paresis occurs. If the cervical segments are affected, this will be hemiparesis (arm and leg); if the thoracic segments are affected, paresis is limited to the leg. At the level of the lesion itself, segmental disorders develop: peripheral paresis (due to involvement of anterior horns or roots) and loss of all sensory modalities with pain (due to posterior horns or roots).
On the opposite side (contralaterally), pain and temperature sensation are impaired according to the pathway type. An important feature: the upper boundary of this anesthesia is located 2–3 segments below the actual lesion site.
Spinal nerve root lesion
Nerve root lesions produce clear local symptomatology:
- Posterior roots: acute, shooting neuropathic pain ("electric shock" sensation) and paresthesias. When several adjacent roots are involved, sensation is lost in a segmental-radicular pattern. A lesion at the limb level leads to hypotonia, decreased reflexes, and sensory ataxia.
- Anterior roots: cause peripheral paresis. Since muscles receive innervation from multiple roots, damage to a single root results in only a partial functional deficit of the muscle.
Cauda equina syndrome develops sequentially. First, pain appears, followed by sensory disturbances and peripheral paresis of the legs with loss of Achilles reflexes. Later, anogenital anesthesia and severe pelvic disorders join: urinary and fecal incontinence without the sensation of passage, impotence, and disappearance of the anal reflex.
Peripheral nerve lesion
Pathology of the nerve trunks themselves is divided into isolated and multiple lesions:
- Isolated lesion (mononeuropathy): manifests as sensory deficits in the zone of a specific nerve, peripheral paresis of the muscles innervated by it, and local autonomic-trophic disturbances.
- Polyneuropathy: symmetrical damage to multiple nerves. Characterized by a polyneuropathic type of anesthesia, multiple paretic states, and pronounced autonomic disorders. Damage to proprioceptive fibers in the legs leads to sensory ataxia.
Electrophysiological methods are used for instrumental diagnostics. ENMG (electroneuromyography) records a decrease in the conduction velocity along the nerve trunk, and EMG (electromyography) can detect changes directly in the innervated muscles.
To memorize the clinical picture of Brown-Séquard syndrome, use the cross-over rule: on the side of the lesion, movement and deep sensation (proprioception) are impaired, whereas on the healthy side, superficial sensation (pain and temperature) is affected.
Class and exam questions
How to differentiate a conus medullaris lesion from an epiconus lesion of the spinal cord?
In lesions of the conus medullaris (S~III~), there is no lower limb paresis, and knee and Achilles reflexes are preserved. In lesions of the epiconus (L~IV~ – S~II~), partial lower limb paresis develops and Achilles reflexes are absent.
What is sensory ataxia and when does it occur?
This is a movement coordination disorder due to the loss of joint-position sense. It appears in lesions of the posterior roots or proprioceptive fibers of peripheral nerves.
How to determine the level of a transverse spinal cord lesion in the acute phase?
In the stage of spinal shock, the upper border of pain sensation disorders serves as a reliable topographic landmark.
What else to study on this topic
- Mechanisms of development of spinal shock and post-shock spastic paresis
- Differential diagnosis of central and peripheral paresis
- Features of pelvic disorders in lesions of various spinal cord levels
- Electroneuromyography (ENMG) and electromyography (EMG) in topical diagnostics
Master the entire topic in the "Neurology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Peripheral nervous system lesion syndromes" and 907 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 32 video lessons for the subject
Other topics in "Chapter 3. Syndromes of lesions of the spinal cord, its roots, peripheral nerves, and nerve plexuses"
Entire section "Chapter 3. Syndromes of lesions of the spinal cord, its roots, peripheral nerves, and nerve plexuses"Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.