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|LETTER TO EDITOR
|Year : 2017 | Volume
| Issue : 1 | Page : 188-189
An unusual cause of bilateral tongue wasting and weakness
Aastha Takkar, Aditya Choudhary, Manoj K Goyal, Manish Modi, Vivek Lal
Department of Neurology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
|Date of Web Publication||12-Jan-2017|
Manoj K Goyal
Department of Neurology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh - 160 012
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Takkar A, Choudhary A, Goyal MK, Modi M, Lal V. An unusual cause of bilateral tongue wasting and weakness. Neurol India 2017;65:188-9
Approximately 10% of patients with peripheral neuropathy of unknown cause have paraproteinemia. Here, we report the case of an elderly gentleman who presented with lingual palsy in association with IgG monoclonal gammopathy of uncertain significance (MGUS).
A 62-year-old gentleman presented with rapidly progressive dysarthria of 25-day duration. Language examination revealed dysarthria (difficulty in speaking lingual syllables) and bilateral asymmetric weakness, wasting, and fasciculation of tongue muscles [Figure 1]. Routine blood, bone marrow examination, skeletal survey, abdominal fat pad biopsy, urine electrophoresis, and conventional nerve conduction study were normal. Serum protein electrophoresis revealed M-band in gamma region. Immunofixation revealed IgG paraproteinemia with M band, along with kappa light chains. Needle electromyography revealed denervation in tongue muscles in the form of fibrillations.
He was diagnosed as a case of IgG MGUS with isolated bilateral hypoglossal neuropathy and was treated with methylprednisolone pulse following which he improved significantly. He had a relapse after 1 month for which he received methylprednisolone pulse followed by oral steroids along with methotrexate. He improved significantly and was doing well at one and a half years of follow up.
The single largest cause of paraproteinemia (66%) is MGUS, which is defined by the following criteria: M protein concentration <3 g/dL; <10% plasma cells in the bone marrow; little or no M protein in urine; absence of lytic bone lesions; and absence of anemia, hypercalcemia, or renal insufficiency. The classic neuropathy associated with IgM MGUS with anti-myelin associated glycoprotein (MAG) antibody is the distal demyelinating sensory ataxic neuropathy with action and postural tremors. Neuropathies with IgM non-MAG MGUS represent a more diverse pattern and can be sensorimotor, dominantly sensory, or dominantly motor. Furthermore, neuropathy may be asymmetric, involve the cranial nerves, and have a more rapid progression., Unlike IgM MGUS, polyneuropathies associated with IgG or IgA MGUS are more heterogeneous and may also present acutely as mononeuritis multiplex or cranial neuropathies.
Our patient had IgG MGUS and presented with isolated bilateral hypoglossal nerve involvement. This presentation has not been reported in the literature. This seminal report of such a presentation, further expands the clinical spectrum of paraproteinemic neuropathies. Though the pathogenic role of IgG paraprotein may be debated, the fact that the patient required long-term immunomodulation for maintaining improvement suggests the important pathogenic role for paraproteins. This clinical commentary provides an insight towards considering the possibility of paraproteinemia in the patients presenting with disorders of the peripheral nervous system.
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