Abstract

ROCHA PAGES, Valeria; HACKEMBRUCH, Heber  and  MUXI, Pablo. Anti–Myelin-Associated Glycoprotein (MAG) Neuropathy: Case Report. Rev. Méd. Urug. [online]. 2025, vol.41, n.4, e702.  Epub Oct 31, 2025. ISSN 0303-3295.  https://doi.org/10.29193/rmu.41.4.11.

Anti–myelin-associated glycoprotein (MAG) neuropathy is a chronic demyelinating neuropathy characterised by distal demyelination of the peripheral nerve. It manifests mainly with paraesthesias and progressive ataxia. We present the clinical case of an 83-year-old man with diabetes, who had been experiencing paraesthesias in the lower limbs (LL) for four years, of a stable nature. During the past year, paraesthesias in the hands and gait instability were added. On examination, postural tremor of the hands, preserved strength, generalised areflexia, distal hypoesthesia, and pallesthesia in the LL with a length-dependent pattern were observed. He also presented with unsteady stance and a Romberg sign without latency.

Given the presence of a distal symmetric sensory syndrome with proprioceptive ataxia, a sensory neuropathy with a clinical-evolutionary change was considered. Nerve conduction studies showed absent sensory potentials. Motor potentials displayed slightly reduced conduction velocities but markedly increased distal latencies (distal demyelination). Cerebrospinal fluid revealed proteinorrachia without cells. In addition, a monoclonal IgM component and positive anti-MAG antibodies were detected. Malignant lymphoproliferative disorders, amyloidosis, and POEMS were ruled out.

Anti-MAG neuropathy is a chronic inflammatory neuropathy associated with monoclonal gammopathies. Clinically, it is characterised by distal paraesthesias and sensory ataxia that progress in a length-dependent pattern, while nerve conduction studies detect distal demyelination. Anti-MAG antibodies are fundamental, as their reaction against glycoproteins in the distal segment of the peripheral nerve explains the condition.

Anti-MAG neuropathy should be suspected in patients with suggestive clinical features. Electrophysiological studies and serology, in association with the monoclonal component, allow an accurate diagnosis.

Keywords : Anti-MAG neuropathy; Chronic demyelinating neuropathy; Myelin-associated glycoprotein.

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