First diagnostic criteria for atopic myelitis with special reference to discrimination from myelitis-onset multiple sclerosis

Clinical Approach to Myelopathy Diagnosis

OBJECTIVE

This article describes an integrative strategy to evaluate patients with suspected myelopathy, provides advice on diagnostic approach, and outlines the framework for the etiologic diagnosis of myelopathies.

LATEST DEVELOPMENTS

Advances in diagnostic neuroimaging techniques of the spinal cord and improved understanding of the immune pathogenic mechanisms associated with spinal cord disorders have expanded the knowledge of inflammatory and noninflammatory myelopathies. The discovery of biomarkers of disease, such as anti-aquaporin 4 and anti-myelin oligodendrocyte glycoprotein antibodies involved in myelitis and other immune-related mechanisms, the emergence and identification of infectious disorders that target the spinal cord, and better recognition of myelopathies associated with vascular pathologies have expanded our knowledge about the broad clinical spectrum of myelopathies.

ESSENTIAL POINTS

Myelopathies include a group of inflammatory and noninflammatory disorders of the spinal cord that exhibit a wide variety of motor, sensory, gait, and sensory disturbances and produce major neurologic disability. Both inflammatory and noninflammatory myelopathies comprise a broad spectrum of pathophysiologic mechanisms and etiologic factors that lead to specific clinical features and presentations. Knowledge of the clinical variety of myelopathies and understanding of strategies for the precise diagnosis, identification of etiologic factors, and implementation of therapies can help improve outcomes.

Activation of Dopamine D2 Receptor Alleviates Neuroinflammation in a Mouse Model of Allergic Rhinitis With Olfactory Dysfunction

PURPOSE

Allergic rhinitis (AR) is a common otolaryngology disease and one of the clinical causes of olfactory dysfunction (OD). The olfactory bulb serves as a transfer station for olfactory information transmission, and alleviating its neuroinflammation may be expected to improve AR-induced OD. Recent studies have suggested that the dopamine D2 receptor acts as a key target in regulating immune functions and neuroinflammatory reaction. However, the effect of dopamine D2 receptor on AR-induced neuroinflammation is still unknown.

METHODS

An AR mouse model with OD induced by ovalbumin were constructed. The buried food pellet test was to evaluate the olfactory function of the mice. Immunofluorescence staining, hematoxylin and eosin staining, enzyme-linked immunosorbent assay and western blotting were also used to investigate the molecular mechanisms underlying the anti-inflammatory effects of the dopamine D2 receptor in AR-induced OD.

RESULTS

We found that AR-induced OD has a relationship with inflammatory responses in the olfactory bulb. Nasal administration of quinpirole (Quin, a dopamine D2 receptor agonist, 3 mg/kg) improved olfactory function in mice, inhibited the expression of toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signalings and the levels of tumor necrosis factor-α, interleukin (IL)-1β and IL-6 in the olfactory bulb. In vitro, Quin (20 μmol/L) inhibited the release of TLR4/NF-κB signalings-dependent inflammatory cytokines in cultured microglia.

CONCLUSIONS

Activation of the dopamine D2 receptor inhibits the release of inflammatory cytokines through TLR4/NF-κB signaling in the olfactory bulb microglia, and protects olfactory function.

Novel Neuropathic Pain Mechanisms Associated With Allergic Inflammation

Allergic diseases are associated with central and peripheral nervous system diseases such as autism spectrum disorders and eosinophilic granulomatosis with polyangiitis, which frequently causes mononeuritis multiplex. Thus, it is possible that patients with an atopic constitution might develop multifocal inflammation in central and peripheral nervous system tissues. In a previous study in Japan, we reported a rare form of myelitis with persistent neuropathic pain (NeP) in patients with allergic disorders. However, the underlying mechanism of allergic inflammation-related NeP remains to be elucidated. First, we analyzed the effect of allergic inflammation on the nociceptive system in the spinal cord. Mice with atopy showed microglial and astroglial activation in the spinal cord and tactile allodynia. In a microarray analysis of isolated microglia from the spinal cord, endothelin receptor type B (EDNRB) was the most upregulated cell surface receptor in mice with atopy. Immunohistochemical analysis demonstrated EDNRB expression was upregulated in microglia and astroglia. The EDNRB antagonist BQ788 abolished glial activation and allodynia. These findings indicated that allergic inflammation induced widespread glial activation through the EDNRB pathway and NeP. Second, we investigated whether autoantibody-mediated pathogenesis underlies allergic inflammation-related NeP. We detected specific autoantibodies to small dorsal root ganglion (DRG) neurons and their nerve terminals in the dorsal horns of NeP patients with allergic disorders. An analysis of IgG subclasses revealed a predominance of IgG2. These autoantibodies were mostly colocalized with isolectin B4- and P2X3-positive unmyelinated C-fiber type small DRG neurons. By contrast, immunostaining for S100β, a myelinated DRG neuron marker, showed no colocalization with patient IgG. Immunoprecipitation and liquid chromatography-tandem mass spectrometry identified plexin D1 as a target autoantigen. Patients with anti-plexin D1 antibodies often present with burning pain and thermal hyperalgesia. Immunotherapies, including plasma exchange, are effective for NeP management. Therefore, anti-plexin D1 antibodies may be pathogenic for immune-mediated NeP, especially under allergic inflammation conditions. Thus, allergic inflammation may induce NeP through glial inflammation in the spinal cord and the anti-plexin D1 antibody-mediated impairment of small DRG neurons.

Long-term outcome in neuroZika

Objective

To characterize the full spectrum, relative frequency, and prognosis of the neurologic manifestations in Zika virus (ZIKV) postnatal infection.

Methods

We conducted an observational study in consecutive ZIKV-infected patients presenting with neurologic manifestations during the French West Indies 2016 outbreak.

Results

Eighty-seven patients, including 6 children, were enrolled. Ninety-five percent of all cases required hospitalization. Guillain-Barré syndrome was the most frequent manifestation (46.0%) followed by encephalitis or encephalomyelitis (20.7%), isolated single or multiple cranial nerve palsies (9.2%), other peripheral manifestations (6.9%), and stroke (1.1%). Fourteen patients (16.1%), including one child, developed a mixed disorder involving both the central and peripheral nervous system. Mechanical ventilation was required in 21 cases, all of whom had ZIKV RNA in at least one biological fluid. Two adult patients died due to neuroZika. Clinical follow-up (median 14 months; interquartile range, 13–17 months) was available for 76 patients. Residual disability (modified Rankin Scale score ≥2) was identified in 19 (25.0%) patients; in 6 cases (7.9%), disability was severe (modified Rankin Scale score ≥4). Among patients with ZIKV RNA detected in one biological fluid, the risk of residual disability or death was higher (odds ratio 9.19; confidence interval 1.12–75.22; p = 0.039).

Conclusions

NeuroZika spectrum represents a heterogeneous group of clinical neurologic manifestations. During an outbreak, clinicians should consider neuroZika in patients presenting with cranial nerve palsies and a mixed neurologic disorder. Long-term sequelae are frequent in NeuroZika. ZIKV reverse-transcription PCR status at admission can inform prognosis and should therefore be taken into consideration in the management of hospitalized patients.

Allergic Inflammation Leads to Neuropathic Pain via Glial Cell Activation

Allergic and atopic disorders have increased over the past few decades and have been associated with neuropsychiatric conditions, such as autism spectrum disorder and asthmatic amyotrophy. Myelitis presenting with neuropathic pain can occur in patients with atopic disorder; however, the relationship between allergic inflammation and neuropathic pain, and the underlying mechanism, remains to be established. We studied whether allergic inflammation affects the spinal nociceptive system. We found that mice with asthma, atopic dermatitis, or atopic diathesis had widespread and significantly more activated microglia and astroglia in the spinal cord than those without atopy, and displayed tactile allodynia. Microarray analysis of isolated microglia revealed a dysregulated phenotype showing upregulation of M1 macrophage markers and downregulation of M2 markers in atopic mice. Among the cell surface protein genes, endothelin receptor type B (EDNRB) was most upregulated. Immunohistochemical analysis revealed that EDNRB expression was enhanced in microglia and astroglia, whereas endothelin-1, an EDNRB ligand, was increased in serum, lungs, and epidermis of atopic mice. No EDNRA expression was found in the spinal cord. Expression of FBJ murine osteosarcoma viral oncogene homolog B was significantly higher in the dorsal horn neurons of asthma mice than nonatopic mice. The EDNRB antagonist BQ788 abolished glial and neural activation and allodynia. We found increased serum endothelin-1 in atopic patients with myelitis and neuropathic pain, and activation of spinal microglia and astroglia with EDNRB upregulation in an autopsied case. These results suggest that allergic inflammation induces diffuse glial activation, influencing the nociceptive system via the EDNRB pathway.

SIGNIFICANCE STATEMENT

The prevalence of allergic disorders has markedly increased over the past few decades. Allergic disorders are associated with neuropsychiatric conditions; however, the relationship between allergic inflammation and CNS complications is unknown. A peculiar myelitis presenting with persistent neuropathic pain has been reported in patients with allergic disorders. We studied how atopy exerts substantial influence on the nociceptive system. We found that mice with allergic disorders had severe allodynia with activated astroglia and microglia, and showed marked upregulation of endothelin-1 (ET-1) receptor type B (EDNRB) in the spinal cord. A selective EDNRB antagonist prevented allodynia and glial activation. Our findings suggest a novel mechanism whereby atopy induces glial activation and neuropathic pain via an ET-1/EDNRB pathway.

A Case of Atopic Myelitis with Cervical Cavernous Angioma

Atopic myelitis, a type of myelitis which appears in patients with elevated serum levels of immunoglobulin E (IgE), occurs more commonly in the cervical spinal cord, but this mechanism has not yet been elucidated. Herein, we experienced a case of atopic myelitis developed during the growth of cervical cavernous angioma caused by bleeding. A 37-year-old woman suffered from hand swelling caused by a house cat licking. At the same time when cavernous angioma had grown, she experienced a numbness in her four extremities, and multifocal peritumoral hyperintense spinal cord signals were seen. The diagnosis of atopic myelitis was made because we observed significantly elevated levels of specific IgE antibody to cat dander. Symptoms disappeared immediately after steroid pulse therapy. We subsequently resected a cavernous angioma, and eosinophil invasion was found inside it. This is the first case report of atopic myelitis which developed in association with spinal cord vascular lesions. A local blood-brain barrier breakdown due to hemorrhagic lesions of the spinal cord may have contributed to the onset of atopic myelitis.

Toxocara canis myelitis involving the lumbosacral region: a case report

CONTEXT

Toxocara canis is a parasite known to cause visceral larva migrans. The infection rarely affects the central nervous system but there have been several reports of myelitis caused by visceral larva migrans due to Toxocara canis. In previous reported cases, the lesions were located in the thoracic or cervical spinal cord. To the best of our knowledge, this is the first report of a lesion involving the lumbosacral region.

FINDINGS

A 60-year-old man developed weakness and dysesthesia in the lower limbs. The symptoms resolved spontaneously, but recurred after five months. One month later, the patient developed pollakiuria and constipation. He was a dog owner and frequently ate raw chicken meat and beef liver. Sagittal T2-weighted image (T2WI) showed swelling and hyperintensity in the spinal cord from T10 to the lumbosacral region and focal nodular enhancement on the posterior segment of the lumbar spinal cord. Blood cell counts showed slight eosinophilia and elevated serum immunoglobulin E level. Cerebrospinal fluid examination showed slight pleocytosis with eosinophilia. Enzyme-linked immunosorbent assay showed high levels of anti-Toxocara antibodies in the serum and cerebrospinal fluid. In addition, confirmatory test by Western blot was positive. The patient was initially treated with intravenous methylprednisolone with slight improvement in muscle weakness. Albendazole was added with a second course of intravenous methylprednisolone. The muscle weakness in the lower limbs improved considerably, and swelling and hyperintensity on T2WI almost disappeared.

CONCLUSION

Our results suggest that Toxocara canis myelitis cannot be discounted even if the myelitis involves the lumbosacral region.

Toxocara canis-Associated Myelitis with Eosinophilic Pneumonia

The existence of Toxocara canis-specific antibodies has recently been reported in patients with atopic myelitis. Here, we report the case of a 35-year-old male patient admitted with a chief complaint of right lower limb hypoesthesia lasting for a month. The patient was diagnosed with eosinophilic pneumonia 3 months ago, and a spine MRI revealed the presence of myelitis in the cervicothoracic cord. After confirming the presence of hyper-IgE-emia and Toxocara canis antibodies, the patient was treated with steroids and albendazole treatment, which improved his symptoms. To our knowledge, this is the first case of Toxocara canis-associated myelitis with eosinophilic pneumonia.

[My way to "Keep Pioneering": integrated neuroscience and immunology research produces a paradigm shift for intractable neurological disease]

The motto of Prof. Yoshigoro Kuroiwa, who established the first independent neurology department in Japan at Kyushu University, is "Keep Pioneering". His students have followed this motto in all fields. I hereby present my efforts to keep pioneering in the following fields: (1) multiple sclerosis (MS); (2) central nervous system (CNS) involvement associated with peripheral atopic inflammation; and (3) care network for patients with intractable neurological disease. In MS, I propose that Th1/Th17 cell-mediated connexin astrocytopathy may play a critical role in producing huge demyelinating lesions in MS, neuromyelitis optica (NMO), and Baló's concentric sclerosis. I discovered a peculiar myelitis that occurred in patients with atopic disorders, and designated it atopic myelitis. In this condition, allodynia and neuropathic pain are cardinal features, regardless of the presence or absence of spinal cord MRI lesions. We found that peripheral atopic inflammation in mice produces allodynia as well as activation of microglia and astroglia in the spinal cord. It is important to involve a variety of medical specialists and care coordinators for collaborative work on medical and social care issues for people with intractable disease. The motto of "Keep Pioneering" in neurology covers not only advanced research for the creation of new therapies for intractable neurological disease, but also caring for actual people with intractable disease, which I believe is the corporate social responsibility of our neurological society. I think that "Keep Pioneering" is a challenging process that never ends throughout one's life.

CCL11 enhances excitotoxic neuronal death by producing reactive oxygen species in microglia

The chemokine CCL11 (also known as eotaxin-1) is a potent eosinophil chemoattractant that mediates allergic diseases such as asthma, atopic dermatitis, and inflammatory bowel diseases. Previous studies demonstrated that concentrations of CCL11 are elevated in the sera and cerebrospinal fluids (CSF) of patients with neuroinflammatory disorders, including multiple sclerosis. Moreover, the levels of CCL11 in plasma and CSF increase with age, and CCL11 suppresses adult neurogenesis in the central nervous system (CNS), resulting in memory impairment. However, the precise source and function of CCL11 in the CNS are not fully understood. In this study, we found that activated astrocytes release CCL11, whereas microglia predominantly express the CCL11 receptor. CCL11 significantly promoted the migration of microglia, and induced microglial production of reactive oxygen species by upregulating nicotinamide adenine dinucleotide phosphate-oxidase 1 (NOX1), thereby promoting excitotoxic neuronal death. These effects were reversed by inhibition of NOX1. Our findings suggest that CCL11 released from activated astrocytes triggers oxidative stress via microglial NOX1 activation and potentiates glutamate-mediated neurotoxicity, which may be involved in the pathogenesis of various neurological disorders.

Regulation of an autoimmune model for multiple sclerosis in Th2-biased GATA3 transgenic mice

T helper (Th)2 cells have been proposed to play a neuroprotective role in multiple sclerosis (MS). This is mainly based on "loss-of-function" studies in an animal model for MS, experimental autoimmune encephalomyelitis (EAE), using blocking antibodies against Th2 related cytokines, and knockout mice lacking Th2-related molecules. We tested whether an increase of Th2 responses ("gain-of-function" approach) could alter EAE, the approach of novel GATA binding protein 3 (GATA3)-transgenic (tg) mice that overexpress GATA3, a transcription factor required for Th2 differentiation. In EAE induced with myelin oligodendrocyte glycoprotein (MOG)35-55 peptide, GATA3-tg mice had a significantly delayed onset of disease and a less severe maximum clinical score, compared with wild-type C57BL/6 mice. Histologically, GATA3-tg mice had decreased levels of meningitis and demyelination in the spinal cord, and anti-inflammatory cytokine profiles immunologically, however both groups developed similar levels of MOG-specific lymphoproliferative responses. During the early stage, we detected higher levels of interleukin (IL)-4 and IL-10, with MOG and mitogen stimulation of regional lymph node cells in GATA3-tg mice. During the late stage, only mitogen stimulation induced higher IL-4 and lower interferon-γ and IL-17 production in GATA3-tg mice. These results suggest that a preexisting bias toward a Th2 immune response may reduce the severity of inflammatory demyelinating diseases, including MS.

Transverse myelitis

Transverse myelitis (TM) includes a pathobiologically heterogeneous syndrome characterized by acute or subacute spinal cord dysfunction resulting in paresis, a sensory level, and autonomic (bladder, bowel, and sexual) impairment below the level of the lesion. Etiologies for TM can be broadly classified as parainfectious, paraneoplastic, drug/toxin-induced, systemic autoimmune disorders, and acquired demyelinating diseases. We discuss the clinical evaluation, workup, and acute and long-term management of patients with TM. Additionally, we briefly discuss various disease entities that may cause TM and their salient distinguishing features, as well as disorders that may mimic TM.