Abstract
Anti-Myelin Associated Glycoprotein (anti-MAG) neurological involvement classically manifests as a peripheral neuropathy with prominent sensitive symptoms. We describe a case report of a patient with positive anti-MAG antibodies presenting with clinical and neurophysiological evidence of spinal cord impairment. A 69-year-old woman came to our attention with subacute onset of dysesthesias at lower limbs and ataxia. Blood routine tests and hematological work-up led to a diagnosis of monoclonal gammopathy of undetermined significance. High titers of anti-MAG antibodies was revealed (34,594.70 BTU/mL, normal range 0–1000). Nerve conduction studies (NCS) ruled out a polyneuropathy at lower limbs. Somatosensory evoked potentials (SSEPs) showed prolonged central conduction time (CTT) at lower limbs, suggesting a dorsal column damage. Brain and spinal cord Magnetic Resonance Imaging (MRI) did not reveal any significant lesion. Analysis of cerebrospinal fluid (CSF) evidenced an albumin-cytologic dissociation. She was treated with corticosteroids with temporary remission of sensory symptoms and normalization of CTT. Subsequently, she developed a multineuropathy which was successfully treated with Rituximab. We discuss the potential role of anti-MAG antibodies in the pathophysiology of dorsal column impairment and the clinical usefulness of SSEPs in monitoring the evolution of anti-MAG neuropathy.
Highlights
IntroductionChronic neuropathies are a common cause of neurological disability worldwide and it is estimated that about one-fifth of these patients do not receive an appropriate etiologic diagnosis demonstrating the clinical challenge in dealing with this type of patients [1]
Chronic neuropathies are a common cause of neurological disability worldwide and it is estimated that about one-fifth of these patients do not receive an appropriate etiologic diagnosis demonstrating the clinical challenge in dealing with this type of patients [1].Ten percent of patients with polyneuropathy of unknown cause have a monoclonal gammopathy, mostly represented by IgM paraglobulinemia [2]
In the present manuscript we report an atypical presentation of anti-MAG neuropathy where initial symptoms and negative Nerve conduction studies (NCS) studies led to perform Somatosensory evoked potentials (SSEPs) demonstrating a dorsal column impairment before the development of polyneuropathy
Summary
Chronic neuropathies are a common cause of neurological disability worldwide and it is estimated that about one-fifth of these patients do not receive an appropriate etiologic diagnosis demonstrating the clinical challenge in dealing with this type of patients [1]. In patients with IgM monoclonal gammopathy associated neuropathy, serum anti-myelin associated glycoprotein (anti-MAG) antibodies are frequently detected at high titers [3]. In atypical presentations of anti-MAG neuropathy, somatosensory evoked potentials (SSEPs) may provide some clinical value because they are able to detect minor proximal neuronal damages which are hardly evidenced by NCS. There are several reports of SSEPs studies in anti-MAG neuropathy patients, the main finding reported is a conduction impairment of the cauda, while a spinal dorsal column damage was never testified [6]. In the present manuscript we report an atypical presentation of anti-MAG neuropathy where initial symptoms and negative NCS studies led to perform SSEPs demonstrating a dorsal column impairment before the development of polyneuropathy
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