Antibody testing in peripheral neuropathies

Serum Antibodies to Glycans in Peripheral Neuropathies

In peripheral neuropathies, such as sensorimotor neuropathies, motor neuron diseases, or the Guillain-Barré syndrome, serum antibodies recognizing saccharide units, portion of oligosaccharides, or oligosaccharide chains, have been found. These antibodies are called anti-glycosphingolipid (GSL) or anti-ganglioside antibodies. However, the information on the aglycone carrying the hydrophilic oligosaccharide remains elusive. The absolute and unique association of GSL to the onset, development and symptomatology of the peripheral neuropathies could be misleading. Here, we report some thoughts on the matter.

Alternating ptosis associated with asialo-GM1 and GD1b antibodies

Miller Fisher syndrome (MFS), variant of acute inflammatory demyelinating polyradiculoneuropathy, is recognized as clinical triad (ophthalmoplegia-ataxia-areflexia). Ganglioside antibodies play an important role in the pathogenesis of acute polyradiculoneuropathy including MFS. To our knowledge, there has been no report of MFS presenting with atypical alternating ptosis or with concurrent elevation of serum GD1 and asialo-GM1 antibody titers, and negative titers of GQ1b antibody such as our patient. Our objective is to report MFS with unusual symptoms and to share our diagnostic approach. We report a rare case of MFS presenting with alternating eyelid ptosis, paresthesia, and ataxia after a respiratory infection. Initial neurological examination revealed left eyelid ptosis, hyporeflexia, positive Romberg sign, and ataxia. The ice pack test was negative. Three days later, contralateral ptosis was observed, associated with areflexia and worsened ataxia. However, there was significant improvement of the previous left eyelid ptosis. Serology revealed elevated asialo-GM1 and GD1b antibodies. Acetylcholine receptor antibodies were negative. Cerebral spinal fluid revealed elevated IgG index. Nerve conduction studies (NCS) performed four days after the onset of symptoms showed normal nerve conduction velocities and F-waves, and absent bilateral H-reflexes. Repetitive nerve stimulation (3 Hz) showed no decrement of compound muscle action potentials. Trial with a single dose of pyridostigmine showed no clinical improvement. The symptoms resolved without intervention. NCS 18 days after onset of symptoms showed mildly prolonged F-waves and absent H-reflexes. This case highlights an atypical presentation of MFS and raises the awareness of a rare autoantibody associated with it.

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.

Antibody testing in peripheral nerve disorders

The identification of autoantibodies associated with dysimmune neuropathies was a major contribution to the characterization of peripheral nerve disorders, the understanding of their pathophysiology, and the clinical diagnosis of neuropathies. Antibodies directed to GM1, GQ1b, and disyalilated gangliosides, and anti-MAG antibodies are very useful in the diagnosis of acute or chronic motor or sensory-motor neuropathies with or without monoclonal IgM. Anti-onconeural anti-Hu and anti-CV2/CRMP antibodies allow when they are detected the diagnosis of paraneoplastic neuropathies. This chapter focuses on the description of these antibodies as diagnostic markers and on their immunopathogenesis. We give a background overview on the origin of these antibodies, their detection, and review those studies, which clearly show that these antibodies are capable of binding to the target tissues in peripheral nerve and thereby can exert a variety of pathophysiological effects. The corresponding electrophysiological and histological changes observed both in human and animal models are exemplified in order to get a better understanding of the immune mechanisms of these antibody-mediated neuropathies.

Relation of sensory peripheral neuropathy in Sjögren syndrome to anti-Ro/SSA

BACKGROUND

Sjögren syndrome is a common, chronic autoimmune disease that typically produces inflammation and poor function of the salivary and lacrimal glands. Other organs can be affected, including the nervous system. Sensory peripheral neuropathy is a common manifestation of the disease.

METHODS

Eight-eight patients attending a dry eyes-dry mouth clinic were diagnosed to have primary Sjögren syndrome and underwent a neurological examination. Anti-Ro (or SSA) and anti-La (or SSB) were determined using immunodiffusion as well as Inno-Lia and BioPlex ANA screen. Serum vitamin B(12) levels were determined using an enzyme-linked microtiter plate assay.

RESULTS

Twenty-seven (31%) of the 88 patients had peripheral neuropathy as defined by loss of light touch, proprioception, or vibratory sensation. Anti-Ro and anti-La were found by immunodiffusion in 12 patients, and 8 of these 12 had neuropathy (χ(2) = 8.46, P = 0.0036, odds ratio = 6.0 compared to those without precipitating anti-Ro and anti-La). Of the 27 patients with only anti-Ro by immunodiffusion, 13 (48.1%) had neuropathy (χ(2) = 5.587, P = 0.018, compared to those without anti-Ro). There was no relationship of the other, more sensitive measures of anti-Ro and anti-La to neuropathy. In addition, we found no association of serum vitamin B(12) levels to neuropathy among these patients with Sjögren syndrome.

CONCLUSIONS

Sensory peripheral neuropathy is common among patients with Sjögren syndrome and is associated with the presence of anti-Ro and anti-La when determined by immunodiffusion.

Antibody testing as a diagnostic tool in autonomic disorders

Some forms of peripheral autonomic dysfunction (especially enteric neuropathy and subacute panautonomic failure) occur as autoimmune phenomena either in isolation or in the context of cancer. Autoimmune autonomic ganglionopathy is an example of a severe, but potentially treatable, antibody-mediated form of autonomic failure. Diagnostic evaluation of autonomic disorders can be supplemented by testing for paraneoplastic antibodies and antibodies against membrane receptors. The diagnostic antibodies most commonly associated with dysautonomia are paraneoplastic antibodies (anti-Hu and CRMP-5) and ganglionic acetylcholine receptor antibodies.