Diagnosis and treatment of chronic acquired demyelinating polyneuropathies

Evidence from Human and Animal Studies: Pathological Roles of CD8(+) T Cells in Autoimmune Peripheral Neuropathies

Autoimmune peripheral neuropathies such as Guillain-Barre Syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP) affect millions of people worldwide. Despite significant advances in understanding the pathology, the molecular and cellular mechanisms of immune-mediated neuropathies remain elusive. T lymphocytes definitely play an important role in disease pathogenesis and CD4⁺ T cells have been the main area of research for decades. This is partly due to the fact that the most frequent animal model to study autoimmune peripheral neuropathy is experimental allergic neuritis (EAN). As it is induced commonly by immunization with peripheral nerve proteins, EAN is driven mainly by CD4⁺ T cells. However, similarly to what has been reported for patients suffering from multiple sclerosis, a significant body of evidence indicates that CD8⁺ T cells may play a pathogenic role in GBS and CIDP disease development and/or progression. Here, we summarize clinical studies pertaining to the presence and potential role of CD8⁺ T cells in autoimmune peripheral neuropathies. We also discuss the findings from our most recent studies using a transgenic mouse line (L31 mice) in which the T cell co-stimulator molecule B7.2 (CD86) is constitutively expressed in antigen presenting cells of the nervous tissues. L31 mice spontaneously develop peripheral neuropathy, and CD8⁺ T cells are found accumulating in peripheral nerves of symptomatic animals. Interestingly, depletion of CD4⁺ T cells accelerates disease onset and increases disease prevalence. Finally, we point out some unanswered questions for future research to dissect the critical roles of CD8⁺ T cells in autoimmune peripheral neuropathies.

Ultrasound in the diagnosis of peripheral neuropathy: structure meets function in the neuromuscular clinic

Peripheral nerve ultrasound (US) has emerged as a promising technique for the diagnosis of peripheral nerve disorders. While most experience with US has been reported in the context of nerve entrapment syndromes, the role of US in the diagnosis of peripheral neuropathy (PN) has recently been explored. Distinctive US findings have been reported in patients with hereditary, immune-mediated, infectious and axonal PN; US may add complementary information to neurophysiological studies in the diagnostic work-up of PN. This review describes the characteristic US findings in PN reported to date and a classification of abnormal nerve US patterns in PN is proposed. Closer scrutiny of nerve abnormalities beyond assessment of nerve calibre may allow for more accurate diagnostic classification of PN, as well as contribute to the understanding of the intersection of structure and function in PN.

Spinal Nerve Root Enhancement on MRI Scans in Children: A Review

Spinal nerve root enhancement in pediatric patients is generally nonspecific, and clinical and laboratory correlation is essential. Nerve root enhancement indicates lack of integrity of the blood-nerve barrier. In this review, we will present a range of pediatric conditions that can present with spinal nerve root enhancement including inflammatory, infectious, hereditary, and neoplastic causes. Familiarity with the various pathologic entities associated with spinal nerve root enhancement is important for a concise differential diagnosis in the appropriate clinical setting. This will avoid unnecessary additional investigations.

Correlation of Changes in Gait Parameters, With Phenotype, Outcome Measures, and Electrodiagnostic Abnormalities in a Patient With Anti-MAG Neuropathy After Exacerbation and Improvement

Gait impairment is a common presentation in patients with IgM anti-myelin-associated glycoprotein (anti-MAG) antibody demyelinating neuropathy. However, current methods used to assess gait are limited. We report spatiotemporal gait parameters captured by GAITRite, a computerized walkway with embedded pressure sensors. The patient worsened after treatment with rituximab and subsequently improved with intravenous immunoglobulin. Serial gait assessments were performed at baseline and after treatment. Spatiotemporal gait parameters correlated with Medical Research Council sum score, Inflammatory Neuropathy Cause and Treatment disability score, and grip strength. Quantitative gait assessment may provide a new dimension to standard clinical evaluation and may help to clarify treatment response in patients with anti-MAG neuropathy when used in combination with other validated assessment tools.

Ocular Neuromyotonia Associated with Chronic Inflammatory Demyelinating Polyneuropathy

Ocular neuromyotonia (ONM) is a neuro-ophthalmic disorder characterized by episodic diplopia caused by contraction of one or more ocular muscles due to spontaneous excitation of the respective ocular motor nerve. We report a patient whose ocular neuromyotonia arose in the setting of a subacute demyelinating polyneuropathy consistent with chronic inflammatory demyelinating polyneuropathy (CIDP) and subsequently resolved following the initiation of intravenous immunoglobulin (IVIg) for her neuropathy. Our patient provides additional evidence towards the role of demyelination and ephaptic neurotransmission in ocular neuromyotonia and also represents the first reported case of ocular neuromyotonia associated with a systemic neurological condition.

New insights into the management of chronic inflammatory demyelinating polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and its variants can be challenging to diagnose and treat. A combination of clinical, electrophysiological and laboratory features is often required to reach a diagnosis. New data are emerging about potential biomarkers and factors that may indicate treatment needs in individual patients. High-quality evidence exists for the efficacy of intravenous immunoglobulin (IVIG) in the treatment of CIDP, including quality of life (QoL) benefits. Besides pharmacological treatment, psychological factors must also be addressed to improve patients' QoL. Home-based IVIG infusion therapy is currently a well-established approach in some countries. A 6-month pilot study conducted in Ontario, Canada, provided proof of safety and patient acceptance of home-based IVIG therapy, although some logistical issues emerged.

POEMS syndrome with vascular transformation of the lymph node sinuses: A case report

POEMS syndrome is a rare multisystem disorder associated with the clinical signs of polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy and skin changes. However, there is often a delay in the diagnosis due to a lack of overall consideration of the symptoms collectively. For this reason, POEMS syndrome is frequently mistaken for other diseases, such as chronic inflammatory demyelinating polyneuropathy. The present study reports the case of a 40-year-old female patient, who presented with a progressive lack of strength in the lower limbs and a unilateral cervical lump. The patient's enlarged cervical lymph nodes were mistaken for local hemangioma. However, subsequently POEMS syndrome with vascular transformation of the lymph node sinuses (VTS) was diagnosed. The patient received glucocorticoid treatment (20 mg prednisone acetate, daily), which is ongoing. The most recent follow-up examination revealed that the patient's strength had improved and at the time of writing the patient remained alive. The study discusses the clinical manifestations, auxiliary examinations and reason for the misdiagnosis. Hematoxylin and eosin staining and cluster of differentiation 31 immunostaining were adopted to identify the VTS. To the best of our knowledge, this is the first report of POEMS syndrome with VTS.

The Ultrasound pattern sum score - UPSS. A new method to differentiate acute and subacute neuropathies using ultrasound of the peripheral nerves

OBJECTIVE

Ultrasound differentiation of neuropathies is a great challenge. We, therefore, suggest a standardized score to operationalize differentiation between several acute and subacute onset neuropathies.

METHOD

We retrospectively analyzed the ultrasound data of 61 patients with acute or subacute neuropathies, e.g. chronic immune-mediated neuropathies, Guillain-Barré syndrome (GBS), and axonal/vasculitic neuropathies. We compared these data to 28 healthy controls. Based on these results an ultrasound pattern sum score (UPSS) with three sub-scores (UPS-A for the sensorimotor nerves, UPS-B for the cervical roots and the vagal nerve and UPS-C for the sural nerve) was developed. Afterwards, the applicability of the score was prospectively validated in 10 patients with chronic neuropathies and in 14 patients with unknown acute and subacute PNP before performing additional tests.

RESULTS

UPS-A and UPSS were significantly higher in CIDP than in other neuropathies and controls (p<0.001). UPS-B was significantly more often pathologic in GBS than in CIDP and other neuropathies (p<0.001). Using receiver operation characteristics curve analysis boundary values for each score were defined. Positive predictive value (PPV) of these scores for CIDP and GBS was >85%. Vasculitic neuropathies showed an intermediate type of UPSS compared to other axonal neuropathies (p<0.001). In the prospective application the pattern score could be used with good accuracy in several types of neuropathy.

CONCLUSION

UPS-A and UPSS operationalize to diagnose acute and subacute-onset CIDP and its variants with high sensitivity, specificity, and PPV. An increased UPS-B with normal UPSS and other sub scores may point to the diagnosis of GBS with high PPV and enables the differentiation from CIDP.

SIGNIFICANCE

Using the UPSS and its sub-scores gives a new diagnostic power to the method of the peripheral nerve ultrasound.