Impact of 2021 European Academy of Neurology/Peripheral Nerve Society diagnostic criteria on diagnosis and therapy of chronic inflammatory demyelinating polyradiculoneuropathy variants

BACKGROUND AND PURPOSE

There are different criteria for the diagnosis of different variants of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). The 2021 European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) guidelines provide specific clinical criteria for each CIDP variant even if their therapeutical impact has not been investigated.

METHODS

We applied the clinical criteria for CIDP variants of the 2021 EAN/PNS guidelines to 369 patients included in the Italian CIDP database who fulfilled the 2021 EAN/PNS electrodiagnostic criteria for CIDP.

RESULTS

According to the 2021 EAN/PNS clinical criteria, 245 patients achieved a clinical diagnosis of typical CIDP or CIDP variant (66%). We identified 106 patients with typical CIDP (29%), 62 distal CIDP (17%), 28 multifocal or focal CIDP (7%), four sensory CIDP (1%), 27 sensory-predominant CIDP (7%), 10 motor CIDP (3%), and eight motor-predominant CIDP (2%). Patients with multifocal, distal, and sensory CIDP had milder impairment and symptoms. Patients with multifocal CIDP had less frequently reduced conduction velocity and prolonged F-wave latency and had lower levels of cerebrospinal fluid protein. Patients with distal CIDP more frequently had reduced distal compound muscle action potentials. Patients with motor CIDP did not improve after steroid therapy, whereas those with motor-predominant CIDP did. None of the patients with sensory CIDP responded to steroids, whereas most of those with sensory-predominant CIDP did.

CONCLUSIONS

The 2021 EAN/PNS criteria for CIDP allow a better characterization of CIDP variants, permitting their distinction from typical CIDP and more appropriate treatment for patients.

Lewis-Sumner syndrome: contribution of diffusion tensor imaging in its differential diagnosis

Lewis-Sumner syndrome (LSS) is an atypical variant of chronic inflammatory demyelinating polyneuropathy characterized by an asymmetric sensory-motor neuropathy with multifocal distribution. The diagnosis is typically clinical and electrophysiological but in some cases might be challenging causing a significant therapeutic delay. Diffusion tensor imaging (DTI) has been progressively used for the in vivo assessment of peripheral nerves integrity. In this study, we aimed to elucidate if DTI was able to detect the specific nerve damage in a patient with suspected LSS, and determine if DTI presented a specific pattern that could be useful in its differential diagnosis. A 38-year-old male with a right foot drop was studied. Physical examination, electrodiagnostic, and MRI studies were performed. MRI of the lower limb was acquired in a 3-T scanner and included T1-wi, T2-TSE-SPIR, and PD-TSE-SPAIR images in axial and coronal planes. Axial DTI was acquired using a single-shot EPI sequence with diffusion encoding in 32 directions. The electrodiagnostic tests suggested a demyelinating sensorimotor neuropathy with conduction blocks. Conventional MRI was normal. DTI showed pathological results in Tibial and Peroneal nerves consisting of thinning and discontinuities along both nerves but more significant in the Peroneal. Compared with MRI, DTI offered a significant improvement to detect the specific nerve damage and its characteristics. The observed nerve damage in DTI suggested polyneuropathy and was compatible with the electrophysiological findings, endorsing the LSS diagnosis. This is the first report in the literature presenting the DTI findings in LSS.

Focal chronic inflammatory demyelinating polyradiculoneuropathy: Onset, course, and distinct features

Focal chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is defined as involving the brachial or lumbosacral plexus, or one or more peripheral nerves in one upper or one lower limb (monomelic distribution). However, other auto-immune neuropathies such as Lewis-Sumner syndrome (LSS) and multifocal motor neuropathy (MMN) can also have a focal onset. From a retrospective cohort of 30 focal CIDP patients with a monomelic onset dating back at least 2 years, we distinguished patients with plexus involvement (focal demyelinating plexus neuropathy [F-PN], n = 18) from those with sensory or sensorimotor (F-SMN, n = 7), or purely motor (F-MN, n = 5) impairment located in one or several peripheral nerves. Few (39%) F-PN patients had motor nerve conduction abnormalities, but the majority showed proximal conduction abnormalities in somatosensory evoked potentials (80%), and all had focal hypertrophy and/or increased short tau inversion recovery image signal intensity on plexus MRI. Impairment remained monomelic in most (94%) F-PN patients, whereas abnormalities developed in other limbs in 57% of F-SMN, and 40% of F-MN patients (P = .015). The prognosis of F-PN patients was significantly better: none had an ONLS score > 2 at the final follow-up visit, vs 43% of F-SMN patients and 40% of F-MN patients (P = .026). Our findings from a large cohort of focal CIDP patients confirm the existence of different entities that are typically categorized under this one term: on the one hand, patients with a focal plexus neuropathy and on the other, patients with monomelic sensori-motor or motor involvement of peripheral nerves. These two last subgroups appeared to be more likely to evolve to LSS or MMN phenotype, when F-PN patients have a more distinctive long-term, focal, benign course.

Hyperacute relapse of Lewis-Sumner syndrome during influenza A (H1N1) virus infection

Background

Lewis-Sumner Syndrome (LSS) is considered an asymmetric sensory-motor variant of Chronic Inflammatory Demyelinating Polyneuropathy (CIDP), mostly affecting the limbs distally, with electrophysiological evidence of multifocal motor conduction blocks. Cranial nerve involvement is present in a minority. Various well-known infectious agents, directly or via the host’s immune responses, may trigger or exacerbate acute and chronic peripheral neuropathies, which may manifest clinically through a multitude of signs and symptoms.

Case presentation

We present the case of a 57-year-old male with Lewis-Sumner Syndrome, whose clinical course was quite stable over many years. He developed severe hyperacute relapse of his neuropathic disease in the context of active pneumonia due to influenza A (H1N1) virus infection. During this exacerbation, besides the obvious worsening of the previous asymmetric limb involvement, the patient also manifested left peripheral facial palsy and dysphagia that rapidly evolved over minutes, mimicking a stroke. The patient also showed rapid recovery, with marked improvement of the acute neuropathic dysfunction, immediately after initiation of treatment with oseltamivir. Our hypothesis is that the direct modulation of Na + ion channel activity in the host’s peripheral nerve cell by H1N1 viral proteins could cause acute and potentially reversible dysfunction in the conduction of nerve action potentials. Direct viral neuritis could also have been the cause. Immunomodulatory agents, namely IVIg, were not administered due to the swift clinical improvement noticed in the following days.

Conclusions

We aim to raise awareness of the possibility of atypical neurological presentations of viral infections, especially relevant in the context of the pandemic the world is now facing.

Comparison of Lewis-Sumner syndrome with chronic inflammatory demyelinating polyradiculoneuropathy patients in a tertiary care centre

BACKGROUND AND PURPOSE

Whether the Lewis-Sumner syndrome (L-SS) is a distinct entity from other types of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP-ot) remains controversial.

METHOD

The clinical/electrophysiological characteristics and long-term outcomes of 45 L-SS and 35 CIDP-ot patients were retrospectively compared.

RESULTS

The CIDP-ot group was composed of 11 patients with a typical CIDP, 17 with a pure sensory form, four with a distal form and three with a pure motor form. In the L-SS group, asymmetric (P < 0.001) and monomelic involvement (P = 0.04) of the upper limbs (P < 0.001) was significantly more frequent; paucisymptomatic forms (Overall Neuropathy Limitations Scale ≤ 1) were less frequent (P < 0.001); electroneuromyography showed that conduction block in intermediate nerve segments was the main demyelinating feature, with frequent F-wave abnormalities on nerves without conduction block (44%). Long-term prognosis was globally poorer in the L-SS group with more frequent aggravation during treatment (P = 0.02), less frequent treatment withdrawal (P = 0.03) and longer time to achieve successful withdrawal (39 vs. 15 months).

CONCLUSIONS

Our study suggests that L-SS patients have a less favourable therapeutic response rate and long-term outcomes. Rapid differentiation of L-SS from other forms of CIDP is important in order to anticipate a more complicated disease course management, with from one side the inefficacy or even harmfulness of corticosteroids and from the other side a difficult weaning procedure. A prospective study is necessary to confirm these results.

[About a Case of Lewis-Sumner Syndrome Observed in Niger]

We report the first documented case of Lewis-Sumner syndrome observed in the Department of Neurology of the National Hospital of Niamey, Niger. It was a 53-year-old man with no known past medical history, who presented paresthesia on the right hand in the median nerve territory about 2 weeks after a flu-like syndrome. The symptoms progressed rapidly in two weeks with asymmetric sensitivomotor involvement of the 4 limbs with a predominance to the upper limbs. The electrophysiological study revealed persistent motor conduction blocks with a decrease in sensory amplitudes and sensory conduction velocities. Cerebrospinal fluid study revealed a proteinorachia at 0.4g/l with normal glycorachia without meningitis. After ruling out other systemic and infectious diseases that explains the clinical picture, the diagnosis of Lewis-Sumner syndrome has been established in the patient based on clinical and electrophysiological arguments. The patient was treated with intravenous immunoglobulins 0.4g/kg per day during 5 days with a good clinical response.

Motor conduction block and conduction velocity in Lewis-Sumner syndrome and multifocal motor neuropathy

Motor conduction blocks (CBs) and decreased motor nerve conduction velocity (MCV) are both demyelination electrophysiological characteristics. Though CBs are both common in Lewis-Sumner syndrome (LSS) and multifocal motor neuropathy (MMN), they are two distinct disease groups, so their MCV and CBs electrophysiological characteristics may be different. In this paper, we aimed to discuss the relationship between CBs and MCV in Lewis-Sumner syndrome (LSS) and multifocal motor neuropathy (MMN). Sixteen patients with LSS and 11 with MMN were retrospectively collected. Motor nerve conduction studies were performed on bilateral median and ulnar nerves. 16/23 segments with CBs in MMN, and 50/53 segments with CBs in LSS had decreased conduction velocities respectively. There was significant difference in MCV between these two groups (MMN 53.1 ± 12.5 m/s; LSS 34.3 ± 17.1 m/s, mean ± SD, P < 0.05) as well as significant difference in MCV for segment with or without CBs between MMN and LSS patients (P < 0.05). Patients with LSS were prone to be found MCV decrease in segments of motor CB than patients with MMN (P = 0.017). Forty one segments in LSS patients and 6 segments in MMN had MCV ≤ 38 m/s (P < 0.05). There exist two relationships between CB and MCV no matter in LSS or MMN. The characteristics of MCV and CB can be used to distinguish these two disease groups.

Extremely Painful Multifocal Acquired Predominant Axonal Sensorimotor Neuropathy of the Upper Limb

The differential diagnosis of upper extremity mononeuritis multiplex includes neuralgic amyotrophy, vasculitic neuropathy, and Lewis-Sumner syndrome. We describe 3 patients initially suspected of neuralgic amyotrophy, who had an extremely painful, protracted, progressive disease course, not fitting one of these established diagnoses. Nerve ultrasonography showed focal caliber changes of the roots, plexus, and limb nerves. Electromyography showed predominant multifocal axonopathy. Ongoing autoimmune neuropathy was suspected. Steroid treatment provided temporary relief, and intravenous immunoglobulin A sustained pain decrease and functional improvement. These patients appear to have extremely painful axonal inflammatory neuropathy, with a good response to immune-modulating treatment.

Upper Extremity Multifocal Neuropathy in a 10-Year-Old Boy Associated With NS6S Disaccharide Antibodies

We present a 10-year-old boy with a predominantly motor multifocal neuropathy with demyelinating and axonal changes with sensory involvement, affecting only one upper extremity. Laboratory studies revealed an elevated titer of immunoglobulin M (IgM) antibodies against the NS6S antigen. He responded to treatment with high dose intravenous immunoglobulins. Focal or multifocal immune-mediated neuropathies are not common in children and may be underdiagnosed.

Nerve biopsy findings contribute to diagnosis of multiple mononeuropathy: 78% of findings support clinical diagnosis

Multiple mononeuropathy is an unusual form of peripheral neuropathy involving two or more nerve trunks. It is a syndrome with many different causes. We reviewed the clinical, electrophysiological and nerve biopsy findings of 14 patients who suffered from multiple mononeuropathy in our clinic between January 2009 and June 2013. Patients were diagnosed with vasculitic neuropathy (n = 6), perineuritis (n = 2), chronic inflammatory demyelinating polyradiculoneuropathy (n = 2) or Lewis-Sumner syndrome (n = 1) on the basis of clinical features, laboratory data, electrophysiological investigations and nerve biopsies. Two patients who were clinically diagnosed with vasculitic neuropathy and one patient who was clinically diagnosed with chronic inflammatory demyelinating polyradiculoneuropathy were not confirmed by nerve biopsy. Nerve biopsies confirmed clinical diagnosis in 78.6% of the patients (11/14). Nerve biopsy pathological diagnosis is crucial to the etiological diagnosis of multiple mononeuropathy.