Motor disorders in spinal cord lesions
The clinical presentation of paresis directly depends on the level of spinal cord compression or destruction (e.g., in tumors or syringomyelia). The symptom complex consists of two types of disorders:
- Segmental disorders: manifest as peripheral paresis strictly at the level of the lesion. For example, in cervical syringomyelia, weakness and atrophy of the hand muscles develop early, later spreading to the shoulder girdle. A cauda equina lesion causes peripheral paresis of the feet.
- Conduction disorders: cause central paresis below the level of the lesion. If the lesion is localized in the cervical region, both arms and legs are affected. With a thoracic lesion, central paresis occurs only in the legs, and with a lumbar lesion, in the distal parts of the legs.
A special place is occupied by Brown-Séquard syndrome (hemisection of the spinal cord). In lateral tumor location, central paresis develops on the side of the lesion, while pain and temperature sensation are lost on the opposite side.
Paresis in carotid territory strokes
Ischemia in the carotid artery territory causes characteristic focal syndromes depending on which specific vessel is occluded.
- Middle cerebral artery (MCA): occlusion of the main trunk results in total contralateral hemiplegia, as well as central paresis of the facial and tongue muscles. Cortical gaze paresis is characteristic. If only MCA branches are affected, hemiparesis predominates in the arm (or an isolated arm monoparesis occurs).
- Anterior cerebral artery: contralateral hemiparesis is more pronounced in the leg and proximal arm (leg monoparesis is possible).
- Internal carotid artery: can cause oculopyramidal syndrome — blindness in one eye on the side of the occlusion combined with hemiparesis on the opposite side.
Alternating brainstem syndromes
Circulatory disorders in the vertebrobasilar territory often lead to crossed (alternating) syndromes. A cranial nerve is affected on the side of the lesion, and the limbs on the opposite side.
- Pons syndromes: in Millard-Gubler syndrome, peripheral paresis of the facial muscles occurs on the side of the lesion, and hemiplegia contralaterally. In Foville's syndrome, this is accompanied by paralysis of the lateral rectus eye muscle.
- Midbrain syndromes: Weber's syndrome manifests as oculomotor nerve palsy on the side of ischemia and hemiplegia on the other side. Benedikt's syndrome also causes oculomotor nerve palsy, but contralateral hemiataxia occurs. Parinaud's syndrome (tectal involvement) causes upward gaze palsy.
- Medulla oblongata: in Wallenberg-Saulnier syndrome (lateral medullary syndrome), paralysis of the pharynx, larynx, and palate develops on the side of the lesion.
Occlusion of the basilar artery leads to severe tetraplegia and oculomotor disorders.
Lacunar Infarcts
These are small areas of ischemia that can manifest as isolated motor deficits. Several classic syndromes are distinguished:
- Pure motor stroke: unilateral central paresis of the arm, leg, face, and tongue. The lesion is usually located in the internal capsule, pons, or white matter of the frontal lobe.
- Sensory-motor stroke: mild or moderate hemiparesis combined with hemihypesthesia (internal capsule involvement).
- Dysarthria-clumsy hand syndrome: mild arm weakness accompanied by speech disturbances.
- Ataxic hemiparesis: central hemiparesis accompanied by ataxia in the paretic limbs.
To remember the essence of alternating syndromes, use the rule 'My face, someone else's body': a cranial nerve palsy (face/eyes) occurs on the side of the brainstem lesion, while limb hemiplegia (body) occurs on the opposite side.
Class and exam questions
How does central paresis differ from peripheral paresis in spinal cord tumors?
Peripheral paresis occurs at the level of the tumor itself due to damage to segments, whereas central paresis occurs strictly below the level of the tumor due to compression of the pathways.
What is oculopyramidal syndrome?
This is a condition during internal carotid artery occlusion where blindness occurs on the side of the lesion, while hemiparesis and hemihypesthesia occur on the opposite side.
Which motor disorders are characteristic of syringomyelia?
The disease often debuts with peripheral paresis and hand muscle atrophy. Later, weakness spreads to the shoulder girdle, and central paresis may develop in the legs.
How does pure motor lacunar stroke manifest?
It causes central paresis of the arm, leg, face, and tongue on one side without sensory loss.
What else to study on this topic
- Sensory disorders in nervous system lesions (segmental, conduction, dissociated).
- Topographic diagnosis of spinal cord tumors using MRI.
- Bulbar syndrome and syringobulbia.
- Aphasia, apraxia, and anosognosia in carotid territory strokes.
- Visual disturbances in vascular catastrophes (hemianopia, visual agnosia).
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