Lower motor neuron syndrome in a patient with HER2-positive metastatic breast cancer: A case report and review of the literature

Paraneoplastic neurological syndromes are very rare and often associated to breast, ovarian and small cells lung cancers. Paraneoplastic motor neuron diseases (MNDs) are even rarer, and frequently described in patients with breast cancer. We presented the first case of patient affected by HER2-positive breast tumor and possible paraneoplastic lower motor neuron disease. In literature, few cases are reported but no one highlights the tumor receptors' profile. Instead, HER2-positive breast cancers are prone to be related to anti-Yo-associated paraneoplastic cerebellar disorders. Anti-onconeural antibodies positivity can be rarely found, confirming that paraneoplastic MND have no specific biomarkers. The presence of CSF oligoclonal bands (OBs) suggests the presence of immune-mediated mechanism, in absence of other possible OBs causes.

Progressive Muscular Atrophy

Progressive muscular atrophy (PMA) is a rare, sporadic, adult-onset motor neuron disease, clinically characterized by isolated lower motor neuron features; however, clinically evident upper motor neuron signs may emerge in some patients. Subclinical upper motor neuron involvement is identified pathologically, radiologically, and neurophysiologically in a substantial number of patients with PMA. Patients with subclinical upper motor neuron involvement do not fulfill the revised El Escorial criteria to participate in amyotrophic lateral sclerosis clinical trials. Intravenous immunoglobulin therapy is only marginally beneficial in a small subgroup of patients with lower motor neuron syndrome without conduction block.

Paraneoplastic subacute lower motor neuron syndrome associated with solid cancer

We retrospectively analyzed three patients with pure motor neuronopathy followed for more than four years in our center. The patients presented a rapidly progressive lower motor neuron syndrome (LMNS) over the course of a few weeks leading to a severe functional impairment. The neurological symptoms preceded the diagnosis of a breast adenocarcinoma and a thymoma in the first two patients, one of them with anti-CV2/CRMP5 antibodies. Cancer was not detected in the third patient who had circulating anti-Hu antibodies. A final diagnosis of paraneoplastic syndrome was made after investigations for alternative causes of lower motor neuron syndrome. Early diagnosis, combined treatment of the underlying cancer, and immunomodulatory treatment led to neurological improvement of the disease in two out of the three cases in which the cancer was diagnosed. Cases of subacute LMNS with rapid progression may occur as an expression of a paraneoplastic neurological syndrome. Identification of these syndromes is important, as the treatment of underlying malignancy along with immunomodulatory treatment may result in a favorable long-term outcome of these potentially fatal diseases.

Late-onset spinal motor neuronopathy - a common form of dominant SMA

We previously described two Finnish families with a new autosomal dominant late-onset spinal motor neuronopathy that was mapped to chromosome 22q11.2-q13.2. In the current screening study of 43 lower motor neuron disease patients from Finland and Sweden, we identified 26 new late-onset spinal motor neuronopathy patients sharing the founder haplotype. In addition to the main symptoms and signs: painful cramps, fasciculations, areflexia and slowly evolving muscle weakness, new features such as mild bulbar findings, were identified. The disease is relatively benign in terms of life expectancy and rate of disability progression, and it is therefore noteworthy that three patients were initially misdiagnosed with ALS. Significant recombinants in this new patient cohort restricted the disease locus by 90% to 1.8Mb. Late-onset spinal motor neuronopathy seems not to be very rare, at least not in Finland, with 38 patients identified in a preliminary ascertainment.