No evidence of cancer found in rare case of older man with LEMS
Study shows 2 conditions plus cerebellar ataxia aren't always linked
Written by |
Researchers in India have described the rare case of an older man who developed both Lambert-Eaton myasthenic syndrome (LEMS) and cerebellar ataxia — another neurological disorder that affects coordination and balance — without evidence of cancer.
While cerebellar ataxia is also “uncommon,” per the team, a dual diagnosis of the condition and LEMS primarily is seen in cancer patients, according to the scientists.
As such, this man’s case highlights that “coexistent LEMS and cerebellar ataxia is not invariably paraneoplastic [associated with cancer],” the researchers wrote.
The man’s condition improved significantly after treatment with high-dose corticosteroids, plasmapheresis to remove disease-causing antibodies, and long-term immunosuppression, the team noted.
“Early immunotherapy may improve neurological outcomes even in cancer-negative cases, but long-term oncologic surveillance remains essential,” the researchers wrote. “Looking ahead, larger studies and shared registries will be key to better understand the disease, discover reliable markers, and develop treatments that can be more precise and effective for patients.”
The man’s case, along with a review of previous published reports of co-occurring LEMS and cerebellar ataxia, was described in a study titled “Coexisting cerebellar ataxia and Lambert-Eaton myasthenic syndrome without malignancy: insights from a case and systematic literature review,” which was published in the journal Neurological Sciences.
LEMS is a rare autoimmune disease in which self-reactive antibodies interfere with nerve-muscle signaling, resulting in muscle weakness and other symptoms. In most cases, these antibodies target proteins called P/Q-type voltage-gated calcium channels (VGCCs), reducing the release of acetylcholine, a chemical needed for muscles to contract.
Fast-growing lung cancer often seen alongside LEMS in patients
The disease is often linked to small-cell lung carcinoma, a fast-growing type of lung cancer, though nearly one-third of patients remain free from signs of cancer.
“Cerebellar ataxia is another uncommon … phenomenon that may co-occur with LEMS, typically in the context of [cancer],” the researchers wrote. This neurological condition is caused by damage to the cerebellum, the part of the brain that controls balance and coordination.
Here, the researchers described the case of a 75-year-old man who had both LEMS and cerebellar ataxia without evidence of cancer.
“The dual presentation of LEMS and cerebellar ataxia in the absence of malignancy remains poorly understood,” the team wrote.
The man, who had been a smoker for 30 years, sought teatment for a rapid worsening in balance problems, which he had been experiencing for three years. He reported a wide, unsteady gait and shaking of his legs and arms when trying to move.
Six months after his first symptoms, he developed cerebellar dysarthria, or slurred speech due to cerebellum damage. He also had a sudden need to urinate, frequent urination at night, erectile dysfunction, and a dry mouth.
After three years, his walking suddenly became much worse, and he needed a wheelchair. He then developed double vision, which worsened in the evening. Soon after, his eye movements became completely paralyzed. One week before visiting the hospital, both eyelids began to droop, and he had to lift them with his hands.
On examination, he was found to have severe drooping of both eyelids, complete eye movement paralysis, cerebellar dysarthria, and poor coordination of the arms and legs. He also had weakness in the muscles near the hips, known as proximal weakness, and reduced reflexes, or hyporeflexia, especially at the ankles.
“This combination of proximal weakness and hyporeflexia raised the suspicion of coexistent LEMS,” the researchers wrote.
Cerebrospinal fluid, the fluid around the brain and spinal cord, showed mildly increased immune cells, suggesting inflammation. A brain MRI showed mild cerebellar shrinkage.
Nerve conduction studies, which assess how well muscles and the nerves that control them are working, showed attenuated motor responses that increased by 80% after brief exercise, which is characteristic of LEMS. Blood testing was positive for antibodies against P/Q-type VGCCs, confirming the diagnosis of LEMS.
Man’s symptoms nearly resolved after 3 months of treatment
Because LEMS is often linked to cancer, the man underwent extensive cancer screening. No tumor was found, suggesting what’s known as a nonparaneoplastic form of LEMS.
The man was treated with intravenous, or into-the-vein, methylprednisolone, a corticosteroid, and plasmapheresis, a blood-cleaning procedure meant to remove disease-driving antibodies. His eyelid drooping, eye paralysis, and muscle weakness eased significantly, and his walking improved slightly, allowing him to walk with aid.
He was started on pyridostigmine, a medication used off-label in LEMS that blocks acetylcholine breakdown, because Firdapse (amifampridine), the only LEMS-approved therapy, was not available. Azathioprine, an immunosuppressant, was also started to reduce antibody production.
After three months, the man’s eye symptoms nearly resolved, and he could walk short distances independently. Repeated testing for cancer at six months came back negative.
To know more about LEMS and cerebellar ataxia co-occurrence, the researchers reviewed the medical literature from 1991 to 2025. The team found 67 reported cases, approximately 70% of which were associated with cancer, most commonly small-cell lung carcinoma. The remaining cases, however, had no cancer during follow-up, suggesting an autoimmune cause.
Neurological improvement was similar whether or not cancer was present, but death was more common in patients with cancer (27.1% vs. 5.3%), the data showed.
“The coexistence of LEMS and cerebellar ataxia is an uncommon autoimmune overlap with important clinical implications,” the researchers wrote.
The findings show that LEMS with cerebellar ataxia is not always cancer-related, and early immunosuppressive treatment can improve outcomes, although long-term cancer monitoring remains essential, the team concluded.
