Demyelinating neuropathy with anti-CRMP5 antibodies predating diagnosis of breast carcinoma: favorable outcome after cancer therapy

Autoantibodies in the diagnostic work-up of neuropathy: clinically useful or purely academic?

The search for autoantibodies in patients with acute and chronic neuropathies has become widespread in neurological practice. These tests are more routinely available and therefore are more commonly requested in larger hospitals with neuroscience centres, although they are now also regularly requested from district general hospital settings, including by non-neurologists. However, the clinical value of these frequently expensive tests is often unclear and their impact on management not always obviously beneficial. This article reviews the main immunological tests used to search for specific autoantibodies in the setting of neuropathy and discusses their potential diagnostic importance, together with the eventual therapeutic implications of results obtained.

Clinical characterisation of sensory neuropathy with anti-FGFR3 autoantibodies

OBJECTIVE

Sensory neuropathies (SNs) are often classified as idiopathic even if immunological mechanisms can be suspected. Antibodies against the intracellular domain of the fibroblast growth factor receptor 3 (FGFR3) possibly identify a subgroup of SN affecting mostly the dorsal root ganglion (DRG). The aim of this study was to identify the frequency of anti-FGFR3 antibodies and the associated clinical pattern in a large cohort of patients with SN.

METHODS

A prospective, multicentric, European and Brazilian study included adults with pure SN. Serum anti-FGRF3 antibodies were analysed by ELISA. Detailed clinical and paraclinical data were collected for each anti-FGFR3-positive patient and as control for anti-FGFR3-negative patients from the same centres ('center-matched').

RESULTS

Sixty-five patients out of 426 (15%) had anti-FGFR3 antibodies, which were the only identified autoimmune markers in 43 patients (66%). The neuropathy was non-length dependent in 89% and classified as sensory neuronopathy in 64%, non-length-dependent small fibre neuropathy in 17% and other neuropathy in 19%. Specific clinical features occurred after 5-6 years of evolution including frequent paresthesia, predominant clinical and electrophysiological involvement of the lower limbs, and a less frequent mixed large and small fibre involvement. Brazilians had a higher frequency of anti-FGFR3 antibodies than Europeans (36% vs 13%, p<0.001), and a more frequent asymmetrical distribution of symptoms (OR 169, 95% CI 3.4 to 8424).

CONCLUSIONS

Anti-FGFR3 antibodies occur in a subgroup of SN probably predominantly affecting the DRG. Differences between Europeans and Brazilians could suggest involvement of genetic or environmental factors.

Chronic inflammatory demyelinating polyneuropathy and malignancy: A systematic review

A systematic review of the literature was performed on the association of chronic inflammatory demyelinating polyneuropathy (CIDP) with malignancy. Hematological disorders are the most common association, particulalry non-Hodgkin lymphoma. CIDP frequently precedes the malignancy diagnosis, and there is a favorable CIDP response to treatment more than 70% of the time. Melanoma is the second most common association and may be accompanied by antiganglioside antibodies; CIDP shows a good response to immunotherapy. Other cancers are rare, with variable timings and presentations but good responses to immunomodulation and/or cancer therapy. Unusual neurological features such as ataxia, distal/upper limb predominance, or cranial/respiratory/autonomic involvement may suggest associated malignancy as may abdominal pain, diarrhea/constipation, poor appetite/weight loss, dermatological lesions, and lymphadenopathy. In the appropriate clinical and electrophysiological setting, CIDP associated with cancer should be considered. Immunomodulatory therapy, cancer treatment alone, or a combination may be effective. Muscle Nerve 57: 875-883, 2018.

Pain as a First Manifestation of Paraneoplastic Neuropathies: A Systematic Review and Meta-Analysis

INTRODUCTION

Paraneoplastic neurological syndromes (PNS) consist of a heterogeneous group of neurological disorders triggered by cancer. The aim of this systematic review is to estimate the reported prevalence of pain in patients with paraneoplastic peripheral neuropathy (PPN).

METHODS

A systematic computer-based literature search was conducted on PubMed database.

RESULTS

Our search strategy resulted in the identification of 126 articles. After the eligibility assessment, 45 papers met the inclusion criteria. Full clinical and neurophysiological data were further extracted and involved 92 patients with PPN (54.5% males, mean age 60.0 ± 12.2 years). The commonest first manifestation of PPN is sensory loss (67.4%), followed by pain (41.3%), weakness (22.8%), and sensory ataxia (20.7%). In 13.0% of the cases, pain was the sole first manifestation of the PPN. During the course of the PPN, 57.6% of the patients may experience pain secondary to the neuropathy.

CONCLUSIONS

Pain is very prevalent within PPN. Pain specialists should be aware of this. Detailed history-taking, full clinical examination, and requesting nerve conduction studies might lead to an earlier diagnosis of an underlying malignancy.

Neuromuscular complications in cancer

Cancer is becoming a treatable and even often curable disease. The neuromuscular system can be affected by direct tumor invasion or metastasis, neuroendocrine, metabolic, dysimmune/inflammatory, infections and toxic as well as paraneoplastic conditions. Due to the nature of cancer treatment, which frequently is based on a DNA damaging mechanism, treatment related toxic side effects are frequent and the correct identification of the causative mechanism is necessary to initiate the proper treatment. The peripheral nervous system is conventionally divided into nerve roots, the proximal nerves and plexus, the peripheral nerves (mono- and polyneuropathies), the site of neuromuscular transmission and muscle. This review is based on the anatomic distribution of the peripheral nervous system, divided into cranial nerves (CN), motor neuron (MND), nerve roots, plexus, peripheral nerve, the neuromuscular junction and muscle. The various etiologies of neuromuscular complications - neoplastic, surgical and mechanic, toxic, metabolic, endocrine, and paraneoplastic/immune - are discussed separately for each part of the peripheral nervous system.

Serum markers in small cell lung cancer: opportunities for improvement

Lung cancer is one of the leading causes of death from malignancy worldwide. In particular small cell lung cancers, which comprise about 15-20% of all lung cancers, are extremely aggressive and cure rates are extremely low. Therefore, new treatment modalities are needed and detection at an early stage of disease, as well as adequate monitoring of treatment response is essential in order to improve outcome. In this respect, the use of non-invasive tools for screening and monitoring has gained increasing interest and the clinical applicability of reliable, tumor-related substances that can be detected as tumor markers in easily accessible body fluids is subject of intense investigation. Some of these indicators, such as high LDH levels in serum as a reflection of the disease, have been in use for a long time as a general tumor marker. To allow for improved monitoring of the efficacy of new therapeutic modalities and for accurate subtyping, there is a strong need for specific and sensitive markers that are more directly related to the biology and behavior of small cell lung cancer. In this review the current status of these potential markers, like CEA, NSE, ProGRP, CK-BB, SCC, CgA, NCAM and several cytokeratins will be critically analyzed with respect to their performance in blood based assays. Based on known cleavage sites for cytoplasmic and extracellular proteases, a prediction of stable fragments can be obtained and used for optimal test design. Furthermore, insight into the synthesis of specific splice variants and neo-epitopes resulting from protein modification and cleavage, offers further opportunities for improvement of tumor assays. Finally, we discuss the possibility that detection of SCLC related autoantibodies in paraneoplastic disease can be used as a very early indicator of SCLC.

Paraneoplastic neurological syndromes

PURPOSE OF REVIEW

This review describes relevant advances in paraneoplastic neurological syndromes (PNS) with emphasis on particular syndromes and the impact of antibodies against surface antigens in their management.

RECENT FINDINGS

PNS may present with symptoms that do not raise the suspicion of a paraneoplastic origin. The best example is anti-N-methyl-D-aspartate receptor encephalitis that in adult women frequently associates with ovarian teratoma. An electroencephalogram pattern described as 'extreme delta brush' was recently identified in 30% of patients with this disorder. Isolated myelopathy may have a paraneoplastic origin associated with amphiphysin or CV2 (CRMP5) antibodies. Jaw dystonia and laryngospasm can be the predominant symptom of the brainstem encephalitis associated with Ri antibodies. γ-Aminobutyric acid (GABA)(B) receptor antibodies are the most common antibodies found in patients with limbic encephalitis and small cell lung cancer, and contactin-associated protein 2 antibodies in patients with Morvan's syndrome and thymoma. Lastly, a recent study identified delta/notch-like epidermal growth factor-related receptor (DNER) as the target antigen of Tr antibodies, a marker of cerebellar ataxia and Hodgkin's lymphoma.

SUMMARY

The number of antibodies relevant to PNS is now expanded to those against surface antigens. These antibodies do not confirm the paraneoplastic origin of the syndrome but predict a better response to immunotherapy.