A Young Man with Anti-NMDAR Encephalitis following Guillain-Barré Syndrome

Approach to diagnosis, evaluation, and treatment of generalized and nonlocal dysesthesia: A review

Dysesthesia is an abnormal sensation in the skin that occurs in the absence of any extraordinary stimulus or other primary cutaneous disorders, excluding any delusions or tactile hallucinations. Clinicians have characterized dysesthesias to include sensations such as burning, tingling, pruritus, allodynia, hyperesthesia, or anesthesia. The etiology and pathogenesis of various generalized dysesthesias is largely unknown, though many dysesthesias have been associated with systemic pathologies including malignancy, infection, autoimmune disorders, and neuropathies. Dermatologists are often the first-line clinicians for patients presenting with such cutaneous findings, thus it is crucial for these physicians to be able to methodically work-up generalized dysesthesias to build a working differential diagnosis, follow up with key labs and/or imaging, and offer patients evidence-based treatment to relieve their symptoms. This broad literature review is an attempt to centralize key studies, cases, and series to help guide dermatologists in their assessment and evaluation of complaints of abnormal cutaneous sensations.

N-Methyl-D-Aspartate (NMDA)-Type Glutamate Receptors and Demyelinating Disorders: A Neuroimmune Perspective

N-methyl-D-aspartate receptors (NMDARs) are ionotropic glutamate receptors, highly important in regulating substantial physiologic processes in the brain and the nervous system, and disturbance in their function could contribute to different pathologies. Overstimulation and hyperactivity of NMDARs, termed as glutamate toxicity, could promote cell death and apoptosis. Meanwhile, their blockade could lead to dysfunction of the brain and nervous system as well. A growing body of evidence has demonstrated the prominent role of NMDARs in demyelinating disorders and anti-NMDAR encephalitis. Herein, we provide an overview of the role of NMDARs' dysfunction in the physiopathology of demyelinating disorders such as multiple sclerosis and neuromyelitis optica spectrum disorders.

Presence of Anti-Thyroid Antibodies Correlate to Worse Outcome of Anti-NMDAR Encephalitis

Objective

To investigate the characteristics and prognosis of anti-NMDAR encephalitis with the prevalence of anti-thyroid antibodies (ATAbs).

Methods

The clinical data of anti-NMDAR encephalitis patients admitted to Xuanwu Hospital from January 2012 to August 2018 was prospectively analyzed, and the patients were followed up for 24 months.

Results

A total of 120 patients were enrolled, of which 34.2% (41/120) were positive for ATAbs. The antibodies were more frequent in patients with severe disease compared to the non-severe group (51.4% vs. 25.6%, P=0.008). In addition, prevalence of ATAbs correlated with a higher incidence of disturbed consciousness, autonomic dysfunction, central hypoventilation and mechanical ventilation. The ATAbs-positive patients were also more likely to receive intravenous gamma immunoglobulin and immunosuppressor compared to the ATAbs-negative cases (P=0.006; P=0.035). Although the presence of ATAbs was associated with longer hospital stays and worse prognosis at 6 months (P=0.006; P=0.038), it had no impact on long-term patient prognosis. Positive status of anti-thyroglobulin antibody was an independent risk factor for worse prognosis at 6 months [odds ratio (OR)= 3.907, 95% CI: 1.178-12.958, P=0.026].

Conclusion

ATAbs are prevalent in patients with anti-NMDAR encephalitis, especially in severe cases, and correlate with poor prognosis and impaired short-term neurological recovery.

A Unique Shape of Brainstem Lesion that Caused Orthostatic Hypotension in Anti-NMDAR Encephalitis

After experiencing upper respiratory-tract symptoms, a 41-year-old woman developed encephalitis with consciousness disturbance and respiratory failure. She had external ophthalmoplegia and facial diplegia. Magnetic resonance imaging revealed a brainstem lesion with spared longitudinal pontine bundles. Abnormal findings of the brainstem auditory-evoked potentials and blink reflex supported brainstem damage. The patient was positive for anti-N-methyl-D-aspartate receptor (NMDAR) antibodies. Repeated immunological treatments improved her symptoms, but severe orthostatic hypotension emerged. A head-up tilt test revealed no arginine vasopressin response to hypotension. The atypical symptoms of this case highlighted that the brainstem is one of the pivotal regions in anti-NMDAR encephalitis.

Limbic Encephalitis following Guillain-Barré Syndrome Associated with <b><i>Mycoplasma</i></b> Infection

A 12-year-old girl was admitted to the authors’ hospital due to muscle weakness, gait disturbance, dysarthria, dysphagia, and diplopia. She experienced prodromal fever 10 days before admission. On examination, deep tendon reflex was absent in the extremities, and nerve conduction velocity was decreased in the ulnar nerve. She was diagnosed with Guillain-Barré syndrome (GBS). Despite steroid pulse therapy following administration of intravenous high-dose γ-globulin, clinical manifestations remained unchanged. Therefore, plasma exchange was performed on day 10 of the illness. The titer of serum <i>Mycoplasma</i> immunoglobulin M level was increased. Immunological testing was positive for serum anti-galactocerebroside C antibody. On day 18 of the illness, however, she developed generalized convulsion. Brain magnetic resonance imaging revealed high intensity in the medial temporal lobes, including the hippocampus and thalamus on T2-weighted intensity imaging, which was consistent with limbic encephalitis. Further immunological tests revealed positivity for anti-N-methyl-D-aspartate-type glutamate receptor antibody in the cerebrospinal fluid. She was treated with additional plasma exchange; however, she exhibited residual manifestations including short-term memory disorder, emotional incontinence, and convulsions. This article describes a notable case of limbic encephalitis following GBS associated with prodromal <i>Mycoplasma</i> infection. It is interesting that autoimmune encephalopathy is concomitant with autoimmune polyneuropathy subsequent to <i>Mycoplasma</i> infection.

N-Methyl-d-aspartate Receptor Antibody Encephalitis: A Concise Review of the Disorder, Diagnosis, and Management

Anti-NMDA ( N-methyl-d-aspartate) receptor (anti-NMDAR) encephalitis is one of the most common paraneoplastic encephalitides. It occurs in both sexes, across all age ranges, and may occur in the presence or absence of an associated tumor. Its pathogenesis and clinical presentation relate to the presence of IgG1 or IgG3 antibodies targeting the NR1 subunit of the NMDA receptor, leading to a disinhibition of neuronal excitatory pathways. Initial clinical manifestations may be nonspecific, resembling a viral-like illness; however, with disease progression, symptoms can become quite severe, including prominent psychiatric features, cognitive problems, motor dysfunction, and autonomic instability. Anti-NMDAR encephalitis may even result in death in severe untreated cases. Diagnosis can be challenging, given that initial laboratory and radiographic results are typically nonspecific. The majority of patients respond to first or second-line treatments, although therapeutic options remain limited, usually consisting of tumor removal (if there is confirmation of an underlying malignancy) in conjunction with prompt initiation of immunosuppressive medications along with intravenous immunoglobulins and/or plasma exchange. Although the clinical presentation of anti-NMDAR encephalitis overlaps with several other more common neurological and psychiatric disorders, early diagnosis and treatment is essential for a positive prognosis. Here, we concisely review the pathogenesis, diagnosis, and clinical management of this disease.

Peripheral neuropathy in limbic encephalitis with anti-glutamate receptor antibodies: Case report and systematic literature review

INTRODUCTION

Autoantibodies to the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor and N-methyl-d-aspartate (NMDA) receptor are known to be the causes of autoimmune encephalitis particularly limbic encephalitis. The involvement of the peripheral nervous system is rarely reported.

METHODS

We analyzed the serial nerve conduction studies of a previously reported case of anti-AMPA receptor encephalitis, who was presented with conscious disturbance and quadriplegia. Initial nerve conduction studies (NCS) revealed motor axonal polyneuropathy with active denervation. We also performed systematic review of similar cases with overlapped peripheral neuropathy and glutamate receptor encephalitis through Embase, PubMed, and MEDLINE.

RESULTS

Follow-up NCS of the patient with anti-AMPA receptor encephalitis found reverse of the acute neuropathy, which was compatible with clinical recovery of quadriplegia. The systematic review identified 10 cases with overlapping peripheral neuropathy with anti-AMPA or NMDA receptor encephalitis. Motor or sensorimotor neuropathies were more common than pure sensory neuropathies. Anti-Hu, anti-amphiphysin, or anti-gnaglioside antibodies coexisted in some cases and might be associated with the peripheral symptoms.

CONCLUSIONS

Both anti-AMPA and anti-NMDA receptor encephalitis could overlap with acute peripheral neuropathy. It is important to consider peripheral symptoms and perform diagnostic tests.

The Laboratory Diagnosis of Autoimmune Encephalitis

Autoimmune encephalitis is a group of encephalitis syndromes that cause altered mentality, memory decline, or seizures in association with the presence of serum and cerebrospinal fluid (CSF) autoantibodies (auto-Abs). An early diagnosis enables early treatments. The detection of auto-Abs is a confirmatory diagnosis. Tissue-based assay, cell-based immunoassay, and immunoblotting are used to detect various autoantibodies. The CSF test for the presence of antibodies is important because it is more sensitive and reflects disease activity in many autoimmune encephalitis, although antibody tests can be negative even in the presence of autoimmune encephalitis. EEG is often abnormal, but nonspecific. A unilateral or bilateral medial temporal T2 high signal is a common finding in MRI. Fludeoxyglucose-positron emission tomography is sometimes useful for diagnosis in patients with normal MRI.

Bi-insular cortical involvement in anti-NMDA-receptor encephalitis - a case report

Background

Anti-NMDA-receptor encephalitis is an immune-mediated inflammatory disorder of the central nervous system. Brain MRI is unremarkable in at least 50 % of patients and highly variable in the remaining patients with signal abnormalities in different brain regions. Only scarce reports exist on other imaging modalities.

Case presentation

A 31-year-old woman sub-acutely developed psychosis, behavioural changes, amnesia, alternating states of agitation and mutism, fever and epileptic seizures. Clinically suspected diagnosis of anti-NMDA-receptor encephalitis was confirmed by the detection of anti-NMDA receptor antibodies in CSF and serum. During the acute phase, brain MRI abnormalities were found in both insular cortices and hippocampi, whereas F¹⁸-FDG-PET showed hypermetabolism bilaterally in insular and prefrontal cortex. After resection of the underlying ovarian teratoma and with multimodal immunotherapy the patient substantially improved reaching a modified Rankin Scale score of 2 after 3 months. At follow-up, both hippocampi were still affected on MRI, whereas insular cortex appeared normal; however, both regions showed prominent glucose hypometabolism.

Conclusions

Here, we report bi-insular cortical abnormalities on MRI and F¹⁸-FDG-PET in a patient with anti-NMDA-receptor encephalitis during the acute phase and after clinical improvement.

Multifocal encephalopathy and autoimmune-mediated limbic encephalitis following tocilizumab therapy

A 63-year-old man with rheumatoid arthritis developed multifocal encephalopathy and limbic encephalitis following therapy with tocilizumab, a humanized anti-interleukin-6 receptor antibody. Anti-glutamate receptor ε2 antibodies were later found to be positive in both the serum and cerebrospinal fluid. This case highlights the possibility of the development of encephalopathy after treatment with tocilizumab, which may also induce autoimmune limbic encephalitis.

Ophthalmoplegia and flaccid paraplegia in a patient with anti-NMDA receptor encephalitis: a case report and literature review

We herein report the case of a 26-year-old woman with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis presenting with ophthalmoplegia and flaccid paraplegia. She developed disorientation and hallucination after fever and vomiting. Hypothermia, hypoventilation, hypertension, paralytic ileus and hyponatremia were present. Neurological examination showed mild consciousness disturbance and bilateral ophthalmoplegia on admission, flaccid paraplegia with leg areflexia on Day 4. Anti-NMDAR antibodies were detected in the serum and cerebrospinal fluid samples. Motor nerve conduction velocity was decreased in the tibial and peroneal nerves. F-wave amplitudes were reduced in the tibial nerve. MRI disclosed lesions in the callosal splenium, hippocampus and cerebral subarachnoid regions. In addition to various encephalitic symptoms, physicians should pay more attention to peripheral nerve damage in patients with anti-NMDAR encephalitis.

Anti-N-methyl-D-aspartate receptor encephalitis with serum anti-thyroid antibodies and IgM antibodies against Epstein-Barr virus viral capsid antigen: a case report and one year follow-up

Background

Anti-N-methyl-D-aspartate receptor encephalitis is an increasingly common autoimmune disorder mediated by antibodies to certain subunit of the N-methyl-D-aspartate receptor. Recent literatures have described anti-thyroid and infectious serology in this encephalitis but without follow-up.

Case presentation

A 17-year-old Chinese female patient presented with psychiatric symptoms, memory deficits, behavioral problems and seizures. She then progressed through unresponsiveness, dyskinesias, autonomic instability and central hypoventilation during treatment. Her conventional blood work on admission showed high titers of IgG antibodies to thyroglobulin, thyroid peroxidase and IgM antibodies to Epstein-Barr virus viral capsid antigen. An immature ovarian teratoma was found and removal of the tumor resulted in a full recovery. The final diagnosis of anti-N-methyl-D-aspartate receptor encephalitis was made by the identification of anti-N-methyl-D-aspartate receptor antibodies in her cerebral spinal fluid. Pathology studies of the teratoma revealed N-methyl-D-aspartate receptor subunit 1 positive ectopic immature nervous tissue and Epstein-Barr virus latent infection. She was discharged with symptoms free, but titers of anti-thyroid peroxidase and anti-thyroglobulin antibodies remained elevated. One year after discharge, her serum remained positive for anti-thyroid peroxidase and anti-N-methyl-D-aspartate receptor antibodies, but negative for anti-thyroglobulin antibodies and IgM against Epstein-Barr virus viral capsid antigen.

Conclusions

Persistent high titers of anti-thyroid peroxidase antibodies from admission to discharge and until one year later in this patient may suggest a propensity to autoimmunity in anti- N-methyl-D-aspartate receptor encephalitis and support the idea that neuronal and thyroid autoimmunities represent a pathogenic spectrum. Enduring anti-N-methyl-D-aspartate receptor antibodies from admission to one year follow-up but seroreversion of Epstein-Barr virus viral capsid antigen IgM may raise the important issue of elucidating the triggers and boosters of anti- N-methyl-D-aspartate receptor encephalitis.

[Dramatic improvement in two cases of anti-NMDA receptor encephalitis after immunomodulating therapy]

We report two patients with encephalitis associated with antibodies against NR1-NR2 heteromers of the NMDA receptor that showed dramatic improvement after immunomodulating therapies. A 38-year old woman (case 1) suddenly developed seizures and short term memory loss. Brain MRI appeared almost normal except for a small number of high intensity spots of white matter on T(2) weighted images. Cerebrospinal fluid examination (CFS) disclosed lymphocytic pleocytosis (61/µl) and Qualitative analysis of NR1-NR2 antibodies in both CFS and serum were positive. Although an initial treatment with high-dose methylprednisolone was not beneficial for clinical improvement, intravenous immunoglobulin (IVIg) therapy led to complete recovery from her neurological problems. Repeated general surveys showed no evidence of tumors including ovarian teratoma. A 71-year old man (case 2) suddenly developed seizures and short-term memory loss three days after receiving an influenza vaccination. Brain MRI appeared normal. CSF analysis revealed no pleocytosis and a slight elevation of protein value accompanying oligoclonal IgG band. Qualitative analysis of NR1-NR2 antibodies in both CFS and serum were positive. Intravenous high-dose methylprednisolone caused dramatic improvement and his neurological problems immediately disappeared. Repeated general surveys showed no evidence of tumors, as in case 1. These two cases showed relatively benign clinical courses with no evidence of tumors and were quite different from the well-known encephalitis associated with antibodies against NR1-NR2 heteromers of the NMDA receptor. Our clinical experience in these two cases suggests that the disease spectrum of anti-NMDA-receptor associated encephalitis might be broader than was once considered.