Another interesting case from Krystle Shafer, MD:
A 62 y/o Chinese American male presents to the ED with a chief complaint of nausea, generalized weakness, and vertigo. His physical exam is unremarkable with the exception of slight hand grasp weakness noted in the patient’s right hand compared to his left. He has no noted gait abnormalities or nystagymus. His potassium is noted to be critically low at 2.4 and is repleted, and a noncontrast head CT scan is negative. The patient is diagnosed with hypokalemia secondary to viral gastroenteritis, acute vertigo, and is admitted.
Within hours of being admitted the nursing staff notes that the patient is experiencing progressive weakness. He is unable to transfer himself from stretcher to bed secondary to weakness. His entire upper right extremity is now weak and his lower extremities are becoming weak as well. He is able to lift left arm in the air for five seconds but cannot lift his right arm. Twelve hours later the patient is unable to move his arms or legs bilaterally secondary to profound weakness and is having difficulty speaking and with swallowing water. Light touch sensation remains intact on exam in his bilateral upper and lower extremities. He continues to complain of nausea and vertigo. He soon develops respiratory distress, and is emergently intubated. It is thought that the patient has Guillain-Barre given the progressive nature of the condition.
The patient had an emergent MRI, which demonstrated bilateral ventral-medial medullary infarct. This is a rare diagnosis this is often misdiagnosed as Guillan-Barre syndrome. In 2007 there were only 40 reported cases in the medical literature and it only accounts for less than 1% of brain infarctions. The most common presentation of this disorder is a progressive loss of motor function to the point of quadriplegia with associated dysarthria and dysphagia. Anatomically, the corticospinal tracts within the medullary pyramids as well as the hypoglossal nerve fibers are affected causing the above symptoms. Of note, light tough sensation is spared over entire body as well as sensory and motor functions for the face. Propriception and vibration sensation is however often affected as the medial lemniscal tracts are also found in the medial medulla.
This is clinically different from Guillain-Barre syndrome (which only affects the peripheral nerves) because it is typically not an ascending paralysis, facial muscles are spared, and autonomic dysfunction is absent. Diffusion-weighted MRI reveals a characteristic “heart-appearance” in the medulla as it did with our patient. Like all strokes, these infarcts are closely linked to hypertension and arteriosclerosis: but what happens such that both sides of the medulla are infarcted at the same time? In patients who have bilateral infarct it is suspected that they have an anomalous branch of the vertebral artery which supplies both sides of the medial medullary instead of the normal expected circulation of bilateral branches of the anterior spinal artery. Overall prognosis is poor for these patients and they often suffer from quadriplegia for the rest of their lives.
Need a refresher on Guillain-Barre?
- Look for a history of URI or GI infection preceeding symptoms.
- This is an acute demyelinating polyneuropathy that affects peripheral nerves
- Early on, people experience extremity paresthesias, and then progress to a rapidly ascending symmetric muscle weakness
- Hyporeflexia may be present (lower motor neuron sign), and patients may have autonomic dysfunction
- Respiratory muscles and cranial nerves are involved later
- Onset is hours to days
- Treatment: Supportive care, IVIG, possibly plasma exchange
Ma,L et al. Bilateral medullary infarct presenting as Guillan-Barre-like syndrome”. Clinical neurology and neurosurgery. 2011; 113: 589-591.
Tokuoka, K et al. “A case of bilateral medullar infarction presenting with “heart appearance sign”. Tokai J Exp Clin Med. 2007; 32 (3): 99-102.
AAEM. A Focused Review of the Core Curriculum.