LEMS case shows need for testing to prevent treatment delays – Lambert-Eaton News

The case of an 8-year-old girl with Lambert-Eaton Myasthenic Syndrome (LEMS) who showed no signs of a tumor, but presented with progressive muscle weakness, shows the need for a full analysis and investigation to avoid processing delays.

The report, “Lambert-Eaton myasthenic syndrome in a young girlwas published in BMJ Case Reports.

LEMS is a rare autoimmune disease that results when the body’s immune system mistakenly attacks voltage-gated calcium channels (VGCCs) on nerve cells that play a key role in nerve-muscle communication. The disease is characterized by the gradual onset of muscle weakness, primarily affecting the hips and upper legs.

In most cases, LEMS is seen in adults with a malignancy, often small cell lung cancer. However, LEMS can also occur in the absence of a tumor, most often due to a family history of autoimmune diseases.

So far, 12 reports have described cases of LEMS in children. Of these, only three were linked to a malignancy: a neuroblastoma, which arises in immature nerve cells, in one case; and a lymphoproliferative disorder, characterized by the excessive proliferation of white blood cells, in the other two cases.

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Researchers from the Yale School of Medicine described the case of an 8-year-old Latina girl who was seen in a clinic after having generalized muscle weakness for more than three months. The muscle weakness was more severe in her legs and she had an unsteady gait. She had a family history of thyroid disease.

The girl developed intermittent fevers, a rash along her torso, sore throat, mouth sores, headaches and stomach problems. Symptoms resolved within three months, but were followed by progressive weakness. The girl had difficulty getting in and out of bed, and often lost her balance.

The symptoms worsened for more than two months, after which she went to a clinic and was referred to a neurologist who rushed her to the emergency room for hospitalization. A neurological exam showed the girl had low muscle tone, which was deeper in her legs and arms.

She lacked reflexes in different parts of her body, but her mental state, coordination, and sensation were intact.

Blood tests showed no major alterations, but she was positive for antinuclear antibodies – self-reactive antibodies that target proteins in a cell’s nuclei where genetic information is stored. MRI scans showed minimal damage to nerve cells in the lumbar spine.

She was discharged with a potential diagnosis of muscular dystrophy and was referred as an outpatient to a neuromuscular clinic.

His condition was deemed stable after examination at the clinic nine days later. An electromyogram (EMG), which records electrical signals coming from a muscle in response to a nerve signal, suggested chronic damage to motor nerve cells, which control voluntary muscle movement. The test results were preliminary as the girl did not tolerate the procedure well, however.

A neurologist reviewed these results along with the early MRI of her spine and referred the girl to the hospital for another MRI and a lumbar puncture so that a sample of cerebrospinal fluid (CSF), the fluid surrounding the brain and spinal cord, can be collected and analyzed.

At this point, she was believed to have Guillain-Barré syndrome, a rare condition in which the body’s immune system attacks the nerves.

CSF analysis was negative for cancer-related antibodies, as well as antibodies against SARS-CoV-2, the virus that causes COVID-19, and Lyme disease.

She received intravenous immunoglobulins into the bloodstream for five days to treat Guillain-Barré syndrome, but failed to improve and was again referred to an outpatient clinic for follow-up. His condition showed no change when seen with a neurologist a month later.

An EMG performed under sedation revealed nerve-muscle communication disorders consistent with a neuromuscular junction disorder. Tests for myasthenia gravis (MG), a neuromuscular disease triggered by an autoimmune response, were found to be negative.

The girl was admitted for evaluation and treatment for LEMS and a potential underlying malignancy.

She had five sessions of plasmapheresis, a treatment in which a patient’s plasma – the liquid part of blood – is replaced. Further blood tests revealed that she was positive for VGCC antibodies.

She repeated the MRI of her lumbar spine, which showed no signs of nerve damage. Earlier MRI findings of nerve damage were found to be erroneous. An MRI of the chest, abdomen and pelvis and a full body PET scan, another imaging technique, as well as additional tests, detected no signs of a tumor.

She was diagnosed with LEMS and received treatment with amifampridine (sold as Firdapse, formerly as Ruzurgi) and daily prednisone, a corticosteroid. She also received a two-day course of intravenous immunoglobulins.

Her condition improved after each plasma exchange session. At the time of her discharge, her muscle strength was similar to what she had at her first doctor’s appointment.

This case report highlights “the marked importance of developing a broad differential that includes LEMS, when developing a child with profound weakness to avoid delay in diagnosis and initiation of treatment”, have writes the researchers.

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