A 17-year-old right-handed boy is brought to the emergency department due to brief loss of consciousness after colliding with another player during a football game. The patient reports "fogginess" but has had no headache, vomiting, focal weakness or numbness, or seizures. He has no other medical conditions and takes no medications. Vital signs are within normal limits. On physical examination, the patient demonstrates retrograde amnesia about the game but no focal neurologic deficits. CT angiography of the head reveals no skull fractures or intracranial bleeding, but a small lesion in the left temporoparietal region composed of abnormal vascular channels is noted and is shown in the exhibit. Without treatment of this abnormality, which of the following will most likely occur in this patient?

Question

A 17-year-old right-handed boy is brought to the emergency department due to brief loss of consciousness after colliding with another player during a football game.  The patient reports "fogginess" but has had no headache, vomiting, focal weakness or numbness, or seizures.  He has no other medical conditions and takes no medications.  Vital signs are within normal limits.  On physical examination, the patient demonstrates retrograde amnesia about the game but no focal neurologic deficits.  CT angiography of the head reveals no skull fractures or intracranial bleeding, but a small lesion in the left temporoparietal region composed of abnormal vascular channels is noted and is shown in the exhibit.   Without treatment of this abnormality, which of the following will most likely occur in this patient?

Quizplus · Accepted Answer

11ec160b_39ac_0a3c_9249_a17e153591a8_MD0001_00 This young patient most likely sustained a concussion. Because he lost consciousness and has retrograde amnesia, imaging is performed to evaluate for intracranial hemorrhage. Incidentally, the CT angiogram reveals a cluster of dilated vessels (ie, "bag of worms") in the left temporoparietal region with large arterial feeder vessels. This is consistent with an arteriovenous malformation (AVM). AVMs occur when an artery directly anastomoses with veins without an interposed capillary bed. The resulting high-pressure blood flow through weak vessels (ie, veins) predisposes patients to aneurysm formation and/or spontaneous hemorrhage. Seizures also commonly develop and may be due to local accumulation of hemosiderin, a cortical irritant, from microbleeds. Most AVMs are congenital and sporadic. They can occasionally occur as a component of hereditary hemorrhagic telangiectasia (ie, Osler-Weber-Rendu syndrome), an autosomal dominant disorder associated with mucocutaneous telangiectasias (eg, nasal mucosa, intestinal mucosa) and multiorgan AVMs (eg, lungs, liver, brain). (Choice A) The pulmonary capillaries filter potential debris from the venous blood (eg, clots, bacteria), preventing it from entering the systemic circulation. A pulmonary AVM (but not a cerebral AVM) bypasses this filtering system, leading to paradoxic embolization into the systemic arteries (eg, stroke or brain abscess). (Choice B) Flaccid paralysis can occur with lesions that affect the peripheral nervous system. However, lesions in the CNS lead to upper motor neuron signs (eg, spastic paralysis, hyperreflexia). In addition, cerebral AVMs very rarely lead to motor deficits. (Choice C) AVMs are congenital malformations rather than neoplastic proliferations. Therefore, they are not at risk of malignant transformation. (Choice E) Although some cerebral AVMs are stable and do not lead to either seizures or intracerebral hemorrhage, they never resolve spontaneously. Educational objective: Arteriovenous malformations occur when an artery directly anastomoses with veins without an interposed capillary bed. They may result in spontaneous intracerebral hemorrhage or seizures, or they may be discovered incidentally when brain imaging is obtained for another reason.

A 17-Year-Old Right-Handed Boy Is Brought to the Emergency Department