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Question Date: 29/07/2023

Question: A neurology consult is requested for a 56-year-old man who is exhibiting abnormal jerking movements. Two weeks ago, while in the hospital for pneumonia, he went into sudden cardiorespiratory arrest. Resuscitation efforts in the hospital were successful after 7 minutes. He regained consciousness within 2 days of the arrest. On examination, he is ventilated through a tracheostomy and is not on any medications. He is able to open his eyes and raise both arms on command and show two fingers or a thumbs-up sign. He demonstrates uncontrollable jerking movements in his limbs and trunk whenever a movement is initiated. Basic metabolic panel and liver function are normal<br><br>Which of the following is the most likely diagnosis?

Options:

• Lance-Adams syndrome
• May-White syndrome
• Metabolic myoclonus
• Myoclonic seizures

Correct Answer: Lance-Adams syndrome

Explaination: This patient most likely developed postanoxic myoclonus, also known as Lance-Adams syndrome. This is a subcortical myoclonus that is markedly exacerbated or induced by action or movement. Myoclonus developing after cardiac arrest can be due to concurrent renal failure or medications but, in their absence, is most often seen as a sequela of arrests that are preceded by respiratory insufficiency. This patient had no metabolic or iatrogenic sources for myoclonus. Therefore, the most likely diagnosis is postanoxic myoclonus, which can be treated with levetiracetam, valproate, or clonazepam, singly or in combination. May-White syndrome is a rare mitochondrial disorder with myoclonic ataxia and other features

Reference: Espay AJ, Chen R. Myoclonus. Continuum (Minneap Minn). 2013 Oct;19(5 Movement Disorders):1264-86. doi: 10.1212/01.CON.0000436156.54532.1a. PMID: 24092290.