A case of multifocal motor neuropathy with conduction block associated with gastric and lung adenocarcinoma

Paraneoplastic Neuropathies: What's New Since the 2004 Recommended Diagnostic Criteria

The diagnostic criteria published by the PNS (Paraneoplastic Neurological Syndromes) Euronetwork in 2004 provided a useful classification of PNS, including paraneoplastic neuropathies. Subacute sensory neuronopathy (SSN) was the most frequently observed peripheral PNS, whereas other forms of neuropathy, as sensory polyneuropathy, sensorimotor polyneuropathy, demyelinating neuropathies, autonomic neuropathies, and focal nerve or plexus lesions, were less frequent. At the time of publication, the main focus was on onconeural antibodies, but knowledge regarding the mechanisms has since expanded. The antibodies associated with PNS are commonly classified as onconeural (intracellular) and neuronal surface antibodies (NSAbs). Since 2004, the number of antibodies and the associated tumors has increased. Knowledge has grown on the mechanisms underlying the neuropathies observed in lymphoma, paraproteinemia, and multiple myeloma. Moreover, other unrevealed mechanisms underpin sensorimotor neuropathies and late-stage neuropathies, where patients in advanced stages of cancer—often associated with weight loss—experience some mild sensorimotor neuropathy, without concomitant use of neurotoxic drugs. The spectrum of paraneoplastic neuropathies has increased to encompass motor neuropathies, small fiber neuropathies, and autonomic and nerve hyperexcitability syndromes. In addition, also focal neuropathies, as cranial nerves, plexopathies, and mononeuropathies, are considered in some cases to be of paraneoplastic origin. A key differential diagnosis for paraneoplastic neuropathy, during the course of cancer disease (the rare occurrence of a PNS), is chemotherapy-induced peripheral neuropathy (CIPN). Today, novel complications that also involve the peripheral nervous system are emerging from novel anti-cancer therapies, as targeted and immune checkpoint inhibitor (ICH) treatment. Therapeutic options are categorized into causal and symptomatic. Causal treatments anecdotally mention tumor removal. Immunomodulation is sometimes performed for immune-mediated conditions but is still far from constituting evidence. Symptomatic treatment must always be considered, consisting of both drug therapy (e.g., pain) and attempts to treat disability and neuropathic pain.

Distal acquired demyelinating symmetric (DADS) neuropathy associated with colorectal adenocarcinoma

INTRODUCTION

Paraneoplastic neuropathies are well recognized as a remote effect of cancer, and subacute sensory neuronopathy is a recognized syndrome. Demyelinating neuropathies are relatively rare. Distal acquired demyelinating symmetric (DADS) neuropathy associated with lymphoproliferative disease has been reported previously. We present the association of DADS neuropathy with solid tumor.

METHODS

We report the clinical presentation, electrophysiology, and progress of DADS neuropathy in a patient later found to have colorectal adenocarcinoma.

RESULTS

A patient presented with subacute onset of symmetric distal sensory and motor symptoms. Electrophysiology was typical of DADS neuropathy. Anti-MAG antibodies were initially positive at low titer, and indirect immunofluorescence analysis for anti-nuclear antibodies revealed autoantibodies to centromere nuclear protein-F (CENP-F). There was clinical and electrophysiologic resolution after tumor resection.

CONCLUSIONS

This case describes the presentation of DADS neuropathy as a paraneoplastic syndrome in a patient later found to have colorectal adenocarcinoma.

Paraneoplastic neuropathies

PURPOSE OF REVIEW

This review describes relevant advances in paraneoplastic neuropathies with emphasis on particular syndromes and the impact of new therapies.

RECENT FINDINGS

Sensory neuronopathy may present with symptoms that do not raise the suspicion of a paraneoplastic origin. A recent study on sensory neuronopathies of different causes identified paraneoplastic cases in a group of older (>60 years) male patients with subacute onset early pain, and frequent involvement of the arms. Paraneoplastic sensorimotor polyneuropathies may be confused with chronic inflammatory demyelinating polyneuropathy (CIDP) and in lymphomas with direct infiltration of nerves (neurolymphomatosis). Recent neurophysiological studies indicate that the polyneuropathy of POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M component, and skin changes) can be differentiated from CIDP by the presence of diffuse demyelination and more severe axonal loss. Neuropathy in Waldenström macroglobulinemia is heterogeneous. Up to 38% have demyelinating features and the rest show axonal degeneration due to different causes (dysimmune, amyloidosis, or tumoral infiltration). Isolated case reports suggest that the combination of cyclophosphamide and rituximab may be effective in paraneoplastic neuronopathies. Lenalidomide and dexamethasone are effective to control the neuropathy of POEMS patients who are not suitable for or progress after autologous stem cell transplantation.

SUMMARY

Clinical and neurophysiological studies are helpful to correctly identify particular paraneoplastic neuropathies.