BACKGROUND Multifocal acquired demyelinating sensory-motor neuropathy (MADSAM) is recognized as a variant of chronic inflammatory demyelinating polyneuropathy. The primary characteristics of MADSAM include multifocal sensory loss and muscle weakness, which are frequently asymmetrical and predominantly affect the upper limbs. Involvement of the lower limbs is less commonly observed in MADSAM. CASE REPORT A 27-year-old female patient presented with recurrent numbness and weakness in her left lower limb was admitted to our hospital. Her medical history included episodes of left peripheral facial paralysis and lower-limb numbness and weakness, which had previously improved after short-term oral steroid therapy. In addition to motor and sensory peripheral nerve impairment in the left lower limb, the neurological examination revealed atrophy of the tongue muscle and a leftward deviation of the tongue. Cerebrospinal fluid examination and magnetic resonance imaging indicated no abnormalities. Electromyography suggested demyelination of motor and sensory nerves in the left lower limb. Sural nerve biopsy demonstrated demyelination changes and axonal degeneration. A diagnosis of multifocal sensory and motor neuropathy was considered, and the patient was administered corticosteroids and tacrolimus. As the condition progressed, electromyography showed gradual involvement of both lower limbs, leading to the consideration of MADSAM. Despite treatment with corticosteroids and tacrolimus, the patient experienced relapse. Rituximab was initiated, resulting in symptoms improvement and reduced recurrence without adverse events. CONCLUSIONS Corticosteroids, plasma exchange, and immunoglobulins have been demonstrated to be effective treatments for CIDP. In our MADSAM case, rituximab proved effective when the patient did not respond to corticosteroids and tacrolimus. We propose that rituximab may serve as an alternative option for patients with MADSAM.

Multifocal chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is the most frequent variant of CIDP. It is characterized by asymmetric multifocal sensory and motor impairments. Few cases with monotruncular onset have been described. The aim of the study was to characterize the clinical, electrophysiological, and radiological features of these monotruncular-onset CIDP cases. The records of 145 patients with focal/multifocal CIDP followed in the hospital department revealed 16 patients with an initial clinical involvement limited to one nerve for at least 6 months. Median diagnostic delay was 24 months. The ulnar nerve was the most frequently involved nerve (44%, 7/16). Based on extensive electrodiagnostic testing at initial evaluation, 5 patients (31%) met the electrodiagnostic criteria for CIDP and 8 patients (50%) for possible CIDP. Conduction blocks (CB) were the most frequent conduction abnormalities. Motor evoked potentials using a triple-stimulation technique showed proximal CB in 12/13 patients. Plexus magnetic resonance imaging was abnormal in 13/15 patients (86%), with bilateral short tau inversion recovery (STIR)-hypersignal in 7 patients. Intravenous immunoglobulins (IVIg) were efficient for 12/15 patients (80%). During follow-up (median 8 years), 3 patients retained monotruncular involvement while 13 had a multitruncular worsening. The only difference was that IVIg treatment was started earlier in patients who were still monotruncular at the last visit (11 vs. 87 months, p = 0.015). Monotruncular onset occurred in 11% of the focal/multifocal CIDP cases. Supportive criteria are highly valuable for positive diagnosis of this condition. The natural course tends to be progressive, involving more nerve trunks. Early treatment may prevent the disease from spreading.

Multifocal acquired demyelinating sensory and motor neuropathy (MADSAM) is a rare autoimmune-mediated inflammatory response with negative antibodies which causes demyelination of multiple peripheral nerves in an asymmetric distribution with both motor and sensory deficits. Diagnosis for MADSAM can be clinically challenging, relies on a combination of clinical and electrodiagnostic studies, and symptoms can overlap with other neurological conditions such as systemic lupus erythematosus (SLE). MADSAM is typically asymmetric, demyelinating, and limited to peripheral nerves, whereas SLE is systemic, more commonly axonal, and has vasculitic features. SLE is treated with steroids and immunosuppressants while MADSAM is treated with intravenous immunoglobulin (IVIG), steroids, or plasmapheresis. There is a good short-term prognosis for MADSAM with early treatment, but prognosis can worsen with delayed or inappropriate therapy. We describe a case of a woman in her 50s who presented with progressive generalized weakness, weight loss, muscle atrophy, and numbness. She was initially diagnosed with SLE, but deteriorated despite treatment. A broad differential was considered which included SLE, paraneoplastic syndrome, chronic inflammatory demyelinating polyneuropathy (CIDP), amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), and Guillain-Barré syndrome. Serological studies, neuroimaging studies, nerve conduction studies, and electromyography (EMG) were performed. She was ultimately diagnosed with Lewis-Sumner syndrome, or MADSAM, a variant of CIDP. The case highlights the importance of understanding the various causes of weakness and neuropathy, particularly with an atypical presentation, to pursue the correct diagnostic tests and treatment. The case particularly focuses on the difference between MADSAM and SLE. There is significant clinical overlap between the two, and a misdiagnosis can delay effective treatment and worsen outcomes by allowing progression to more debilitating stages of the illness.