Teen’s leg pain forced her to go to the ER, but there was more to it
A sore throat and trouble speaking had also presented themselves. An unusual diagnosis followed.
A 16-year-old girl came to the emergency room for leg pain that had started in her calves about 24 hours earlier and then spread throughout her legs. She felt so weak, she could not walk without falling, so her parents had to carry her to the car and into the ER.
The girl told us that for the last two months her tongue felt numb, her speech sometimes sounded slurred, and it was harder to swallow. She also had a sore throat for the past two weeks, as did her brother. Before all this started, she had been healthy and active. Our patient was especially upset with her symptoms because they kept her from playing ice hockey.
The triage nurse found all the patient’s vital signs were normal — she did not have a fever or abnormal heart rate or blood pressure. She did not appear to have any difficulty breathing and the oxygen level in her blood stream was normal. But on examination, her speech was slurred, she had decreased leg muscle strength, and her legs were tender.
The doctor noticed something else: the girl appeared “under the influence.” Once her parents were out of the room, the patient said that she smoked marijuana and drank alcohol at parties. In addition, her parents told the doctor that their daughter’s grades had fallen drastically. But both her blood alcohol and urine screens were negative, ruling out substance abuse.
The patient’s throat was very red, consistent with a throat infection (pharyngitis). That finding led to testing for rheumatic fever, which can be the result of an untreated streptococcus throat infection and can cause painful joints. But the strep test also was negative.
Another possibility was Guillain-Barré syndrome (GBS), an autoimmune condition in which the immune system attacks the body’s nerves, causing weakness and numbness often starting in the legs. GBS is often triggered by an infection like pharyngitis. The diagnosis is made by doing a spinal tap and testing the fluid surrounding the brain and spinal cord for elevated levels of protein. The results here, too, were normal.
Multiple sclerosis, which can cause neurological symptoms in different parts of the body, was the next consideration. MS mostly occurs in young women, and its symptoms can worsen over a period of weeks to months. The diagnosis is made by doing an MRI of the brain and spinal cord to look for lesions corresponding with the areas of the nervous system involved. But her MRI was found to be normal, and so the quest for a diagnosis continued.
Solution
For muscles to work, a chemical called acetylcholine must travel along the muscles and activate them. But in a rare autoimmune condition known as myasthenia gravis, acetylcholine is blocked from activating the muscles. MG is derived from both Greek and Latin words and means “grave muscle weakness.” It’s an unusual finding, as perhaps 10 in a million people are diagnosed each year, and very few cases occur in children and teens.
The diagnosis was confirmed by a positive acetylcholine receptor antibody test. There is no cure for this chronic condition, which generally worsens with age, but symptoms can be alleviated by lifelong medication. The girl received a course of corticosteroids to calm her overactive immune system and started physical therapy. Our patient was not letting MG get in the way of her goals and she was back in the rink for the winter ice hockey season.
Kelly Ca is a pediatric resident and Rima Himelstein is an adolescent medicine specialist at Nemours Children’s Health, Delaware.