A 6-year-old boy is brought to the emergency department due to difficulty moving his right arm and leg. The patient was playing alone in his room when his mother heard him fall and then found him unresponsive on the floor. He regained consciousness after 3 minutes, but he was confused and unable to move his right arm and leg. The patient has no known medical conditions and takes no medications. He has had normal development. The patient's mother has a history of migraines, and his maternal uncle died last year from a hemorrhagic stroke. On physical examination, he is alert with normal speech and behavior and no complaints of pain. Heart sounds are normal. CN II-XII are intact. The right upper and lower extremities are flaccid, and right-sided strength is 0/5. Left-sided strength is 5/5 in the upper and lower extremities. Sensation to light touch is intact in all the extremities. CT scan of the head and MRI of the brain are normal. Over the next 4 hours, the patient gradually regains complete motor function in his right arm and leg. Which of the following is the most likely cause of this patient's hemiplegia?
Acute causes of hemiplegia in children | ||
Cause | Historical clues | Key findings |
Ischemic stroke |
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Intracranial hemorrhage |
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Seizure (Todd paralysis) |
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Hemiplegic migraine |
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ATIII = antithrombin III; ICP = intracranial pressure; PFO = patent foramen ovale; SCD = sickle cell disease. | ||
This patient's transient hemiplegia following an episode of loss of consciousness with gradual return to baseline and normal imaging studies is most consistent with Todd paralysis. Todd paralysis is a self-limited, focal weakness or paralysis that occurs in the postictal period after a focal-onset seizure, which may become secondarily generalized. The pathophysiology likely involves neuronal exhaustion.
Physical examination reveals flaccid weakness or paralysis of one or both extremities on the same side of the body, and diagnosis is clinical. However, other causes of paralysis (eg, embolism, intracranial bleed) should be excluded (ie, by CT scan and/or MRI), particularly if there is no clear history of a preceding seizure. In some cases, seizure activity may be subtle or unwitnessed.
Treatment of Todd paralysis is supportive because the symptoms usually resolve within 36 hours.
(Choice A) Congenital heart disease involving the atrial septal wall (eg, patent foramen ovale, atrial septal defect) is a risk factor for a paradoxical embolic stroke via right-to-left shunting. This patient's normal imaging and cardiac examination, previously healthy status, and quick return to baseline make the diagnosis unlikely.
(Choice B) Conversion disorder is uncommon before adolescence and can present with a range of neurologic deficits (eg, nonepileptic seizure, weakness/paralysis, visual changes) without an underlying physiologic abnormality. Risk factors include a history of psychiatric conditions or abuse. Conversion disorder is unlikely given this patient's age and lack of known psychosocial triggers.
(Choice C) Hemiplegic migraine is characterized by migraine headaches preceded by aura with motor weakness. Hemiplegic migraines are more common in adolescents and do not typically cause loss of consciousness, as seen in this patient. In addition, this patient has no headache.
(Choice D) Homocystinuria is a metabolic disorder that can predispose patients to venous or arterial thrombi or emboli. Patients with homocystinuria may also have intellectual disability, Marfanoid body habitus, and lens dislocation, none of which are present in this patient. In addition, an infarct would be visible on imaging.
(Choice E) Intracranial hemorrhage (eg, hemorrhagic stroke, subdural hematoma) can present with acute-onset hemiparesis but would be visible on either brain CT scan or MRI. In addition, symptoms would not be self-limited.
Educational objective:
Todd paralysis is a transient, focal weakness or paralysis (eg, hemiplegia) that occurs in the postictal period after a focal-onset (± secondary generalization) seizure. Symptoms are self-limited and usually resolve within 36 hours.