Are all motor and neuron symptoms in a stroke unilateral?

Motor and Neuron Symptoms in Stroke: Not Always Unilateral

No, not all motor and neuron symptoms in a stroke are unilateral, although unilateral symptoms are more common and characteristic of most strokes.

Typical Unilateral Presentation

• Unilateral weakness (face, arm, and/or leg) is one of the most recognized and highest risk symptoms of stroke 1
• Unilateral sensory changes (numbness, tingling) affecting one side of the body are common symptoms of stroke 1
• Unilateral visual field defects (hemianopia) affecting vision on one side are typical stroke symptoms 1

Exceptions: When Stroke Symptoms Can Be Bilateral or Non-lateralizing

Vertebrobasilar Strokes

• Vertebrobasilar strokes can present with bilateral or non-lateralizing symptoms 1
• Bilateral hearing loss, though rare, can occur from vertebrobasilar strokes 1

Brainstem Strokes

• Can cause symptoms that affect both sides of the body
• Vertigo with other brainstem symptoms can indicate stroke 1
• Dysarthria and dysphagia can occur without lateralizing weakness 1

Specific Neurological Deficits

• Hemispatial neglect, a neuropsychological condition after damage to one hemisphere (typically right), affects attention and awareness of one side of space but is not attributable to primary sensory or motor deficits 2
• Limb apraxia ("difficulty in performing purposeful, skilled movements") can occur after stroke and is more common after left hemispheric than right hemispheric stroke 2

Ipsilateral Effects

Research has shown that stroke can sometimes affect the ipsilateral (same) side of the body, not just the contralateral (opposite) side:

• Studies have demonstrated impairment in the "asymptomatic" arm (ipsilateral to the stroke) on computerized tests of sensory-motor function, though to a lesser degree than the symptomatic arm 3
• This suggests that all cerebral hemisphere areas involved in sensory-motor functions can exert some degree of bilateral motor control, though ipsilateral influence is never greater than contralateral influence 3
• Motor cortical disinhibition in the unaffected hemisphere can occur after unilateral cortical stroke 4

Clinical Implications

• The presence of non-unilateral symptoms should not delay stroke evaluation, as these may still represent stroke 1
• Assuming bilateral symptoms exclude stroke is incorrect and can lead to missed diagnoses 1
• Both unilateral and non-unilateral stroke symptoms may qualify for acute interventions like thrombolysis or thrombectomy when appropriate 1

Rehabilitation Considerations

• Specialized approaches are needed for certain deficits like unilateral spatial neglect 1
• Rehabilitation strategies for limb apraxia may include strategy training, gesture training, or task practice with or without mental rehearsal 2

In summary, while the classic presentation of stroke involves unilateral symptoms (contralateral to the lesion), clinicians should be aware that bilateral or non-lateralizing symptoms can occur in certain stroke types, particularly those affecting the vertebrobasilar system or brainstem. Additionally, subtle ipsilateral effects can be detected with sensitive testing, though these may not be apparent on routine clinical examination.