Central nervous system involvement in patients with monoclonal gammopathy and polyneuropathy

Optic Nerve Demyelination in IgG4 Anti-Neurofascin 155 Antibody-Positive Combined Central and Peripheral Demyelination Syndrome

Optic nerve demyelination is one of the clinical features of combined central and peripheral demyelination (CCPD), an entity with heterogenous immunopathogenesis and clinical characteristics, overlapping between multiple sclerosis (MS) and chronic inflammatory demyelinating polyneuropathy (CIDP). Of interest, earlier studies among patients with CIDP prior to discovery of antibodies against paranodal protein neurofascin 155 (anti–NF 155) also reported optic nerve dysfunction. We aimed to evaluate optic nerve demyelination among anti–NF 155 CIDP patients. We studied 2 patients with anti–NF 155 CIDP using visual-evoked potentials (VEP) and optical coherence tomography (OCT). Both patients had distal acquired demyelinating symmetric (DADS) subtype CIDP. Other common features were prominent sensory ataxia, hand tremors, significantly elevated cerebral spinal fluid protein, high titre anti–NF 155 antibodies and poor response to corticosteroid and intravenous immunoglobulin (IVIg). No central nervous system neuroradiological abnormality detected. Both had normal visual acuity and colour vision, but one had subclinical right relative afferent pupillary defect (RAPD). VEP of both showed bilateral prolonged P100 latencies. OCT for patient with RAPD demonstrated moderate to severe retinal nerve fibre layer (RNFL) thinning. Identification of optic nerve demyelination among subclinical CIDP with anti–NF 155 antibodies expanded the spectrum of demyelination within the subset of CCPD.

Multifocal visual evoked potentials in chronic inflammatory demyelinating polyneuropathy

Objective

Studies using conventional full‐field visual evoked potentials (ffVEP) have reported subtle abnormalities in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). We hypothesize that these abnormalities can be detected in the majority of CIDP patients using enhanced methods.

Methods

We performed a cross‐sectional noninterventional study comparing 18 CIDP patients and 18 matched healthy controls using multifocal VEP (mfVEP) as a technique with enhanced sensitivity to detect conduction abnormalities across the spectrum of optic nerve fibers. Patients with confounding diseases (ophthalmologic, diabetes mellitus) were excluded.

Results

The mean amplitude and latency, as well as the low‐contrast visual acuity, did not differ between CIDP patients and controls. Subanalyses revealed latency differences concerning the superior sector of the visual field. Severity markers of CIDP (ODSS, motor nerve conduction velocity) were associated with mfVEP latency delay.

Interpretation

We could not adduce evidence for clinically or diagnostically relevant visual pathway involvement in CIDP. The latency differences identified were very subtle and restricted to the superior visual field which cannot be readily explained biologically, anatomically, or pathologically. In summary, we conclude that our study revealed no relevant differences in mfVEP parameters between CIDP patients and controls.

[An adult-onset multiphasic disseminated encephalomyelitis (MDEM) presenting favorable response to steroid therapy]

A 64-year-old man presented with acute onset of generalized seizure and encephalopathy. FLAIR images of brain MRI showed multifocal high-intensity lesions of the white matter. Within few days after the treatment with intravenous methylprednisolone (1,000 mg/day for 3 days), amelioration of clinical symptoms and recovery of MRI findings were observed. Six months after the withdrawal of oral steroid therapy, recurrent lesions were observed at the same locations as initially revealed on admission. Due to the concomitant development of peripheral lymphocytosis, a brain biopsy was performed from a right frontal lesion. Histological findings suggested extensive demyelination accompanied by infiltration of inflammatory lymphocytes and macrophages. In spite of the temporary remission after re-initiation of oral steroid therapy, reduction of oral steroid dosage resulted in new lesion formation apart from the initial locations. Based upon clinical features, MRI findings and histological examination, he was diagnosed with multiphasic disseminated encephalomyelitis (MDEM). Acute disseminated encephalomyelitis (ADEM) is one of common causes of demyelinating disease among children. However, multiphasic form of ADEM is particularly rare in adult patients. Here we reported a rare case of adult-onset MDEM, in which clinical, radiological and histological features were described, and efficacy of steroid therapy was highlighted.

Optic and auditory pathway dysfunction in demyelinating neuropathies

OBJECTIVE

The involvement of optic and auditory pathways has rarely been studied in demyelinating polyneuropathies. We here aimed to study this further in a cohort of patients with acquired and gentic demyelinating neuropathy.

METHODS

We studied eight patients with hereditary neuropathy with liability to pressure palsies (HNPP), six with Charcot-Marie-Tooth disease type 1A (CMT1A), ten with chronic inflammatory demyelinating polyneuropathy (CIDP) and seven with antimyelin-associated glycoprotein (MAG) neuropathy using visual evoked potentials and brainstem auditory evoked potentials.

RESULTS

Optic pathway dysfunction was detected in 6/7 anti-MAG neuropathy patients, about half of those with CIDP and HNPP, but only in 1/6 patients with CMT1A. Peripheral auditory nerve dysfunction appeared common in all groups except HNPP. Brainstem involvement was exceptional in all groups.

CONCLUSIONS

We conclude optic nerve involvement may be frequent in all demyelinating polyneuropathies, particularly anti-MAG neuropathy, except in CMT1A. Peripheral auditory nerves may be spared in HNPP possibly due to absence of local compression. Evidence for central brainstem pathology appeared infrequent in all four studied neuropathies. This study suggests that acquired and genetic demyelinating polyneuropathies may be associated with optic and auditory nerve involvement, which may contribute to neurological disability, and require greater awareness.

Clinical phenotype of patients with neuropathy associated with monoclonal gammopathy: a comparative study and a review of the literature

The objective of this study was to investigate if the clinical and electrophysiological phenotype of patients with polyneuropathy associated with IgM monoclonal gammopathy (IgM-PNP) is related to the presence of antibodies against gangliosides or myelin-associated glycoprotein (MAG). We compared clinical and nerve conduction study (NCS) characteristics of 11 IgM-PNP patients with antibodies against asialo-GM1 or gangliosides (GM1, GD1a, GD1b, GM2 or GQ1b) to 11 consecutive IgM-PNP patients with anti-MAG neuropathy and to 9 IgM-PNP patients without antibodies against either MAG or gangliosides. Patients with anti-ganglioside antibodies could not be differentiated from those with anti-MAG antibodies based on clinical characteristics. However, within the group of anti-ganglioside antibody positive patients, antibodies against GD1b and GQ1b were associated with a purely sensory neuropathy (p = 0.002), while asymmetric weakness with symmetric sensory loss was associated with anti-asialo-GM1 antibodies. In conclusion, polyneuropathy associated with IgM monoclonal gammopathy and anti-ganglioside antibodies clinically resembles anti-MAG neuropathy. Pure sensory neuropathy and marked asymmetry may suggest the presence of anti-ganglioside rather than anti-MAG antibodies.