ビッカースタッフ脳幹脳炎

Bickerstaff's brainstem encephalitis (BBE) is an autoimmune disorder typically localized to the brainstem. While cortical involvement is rare, severe cases presenting with decorticate posturing and profound consciousness disturbance can mask typical clinical features, making early diagnosis challenging. A 22-year-old woman developed progressive numbness in her limbs and lips, visual impairment, and impaired consciousness 13 days after an episode of gastroenteritis. Upon admission, she exhibited a Japan Coma Scale score of III-200, decorticate posturing, absent brainstem reflexes, and hyperreflexia. Cerebrospinal fluid analysis revealed pleocytosis and elevated protein levels. Although contrast-enhanced MRI showed only faint enhancement along the leptomeninges of the cerebral cortex and midbrain, acute-phase 123I-IMP cerebral blood flow (CBF) single photon emission computed tomography (SPECT) demonstrated diffuse cortical hypoperfusion and paradoxical hyperperfusion in the bilateral basal ganglia. Furthermore, multiple autoantibodies associated with autoimmune encephalitis and demyelinating diseases-including anti-NMDAR, LGI1, CASPR2, AMPAR, GABABR, DPPX, GlyR, mGluR5, MOG, and AQP4 antibodies-were all negative in both serum and cerebrospinal fluid. Following aggressive immunotherapy, her consciousness improved rapidly. It was only during this recovery phase that the classic BBE triad of total ophthalmoplegia and ataxia became apparent, which had been masked by the initial severe consciousness disturbance. The diagnosis of BBE was retrospectively confirmed based on this clinical evolution and the high titers of serum anti-GQ1b and anti-GT1a IgG antibodies. Follow-up SPECT confirmed the normalization of CBF, correlating with her clinical recovery. This case demonstrates that cerebral perfusion SPECT is capable of detecting reversible dysfunction within the cortex and basal ganglia in BBE. It highlights the importance of considering BBE even in atypical cases with predominant cortical symptoms, where the diagnosis may only become clear through clinical evolution and ancillary functional imaging.

Bickerstaff brainstem encephalitis (BBE) is a rare immune-mediated neurological disorder characterized by a wide spectrum of clinical presentations, often following a preceding infection. Although supportive findings on neuroimaging, cerebrospinal fluid (CSF) analysis, and antiganglioside antibodies may aid diagnosis, the condition remains largely clinical, particularly in atypical cases. We report the case of a 60-year-old man who presented with acute onset of fever and altered sensorium, rapidly progressing to severe quadriparesis and respiratory failure requiring mechanical ventilation. Neuroimaging and CSF analysis were unremarkable, with no evidence of albuminocytological dissociation. Nerve conduction studies revealed severe sensorimotor neuropathy involving all four limbs. In view of poor response to empirical antimicrobial therapy and after exclusion of infectious etiologies, we suspected an autoimmune process and initiated the patient on intravenous immunoglobulin (IVIG). We observed significant clinical improvement from the second dose onward, with progressive recovery of sensorium, motor power, and respiratory function. We successfully weaned the patient off ventilatory support, decannulated, and discharged him without residual neurological deficits. This case highlights the diagnostic challenge that atypical presentations of Bickerstaff encephalitis pose in the absence of classical radiological and CSF findings. It underscores the importance of maintaining a high index of clinical suspicion and initiating timely immunotherapy, even when conventional diagnostic markers are lacking.

BACKGROUND: Bickerstaff Brainstem Encephalitis (BBE) is a rare, post-infectious autoimmune disorder characterized by ophthalmoplegia, ataxia, and altered consciousness. Its significant clinical and serological overlap with Miller Fisher syndrome (MFS) and Guillain-Barré syndrome (GBS) creates diagnostic challenges, particularly in atypical or seronegative presentations. These conditions are collectively understood as components of the anti-GQ1b antibody syndrome, a spectrum of neuro-immune disorders. AIMS: This review provides a clinically focused, integrative synthesis of the anti-GQ1b antibody spectrum, with an emphasis on BBE. We aim to clarify the underlying pathophysiology, delineate the range of clinical phenotypes, provide a structured framework for diagnosis that acknowledges the limitations of ancillary testing, and summarize current evidence for therapeutic strategies. SYNTHESIS OF EVIDENCE: Pathogenesis is primarily driven by anti-GQ1b IgG antibodies, generated following infection via molecular mimicry, which trigger complement-mediated damage to ganglioside-rich neural structures. The clinical presentation ranges from purely peripheral deficits (MFS) to severe central nervous system dysfunction (BBE), with frequent BBE-GBS overlap syndromes. Diagnosis hinges on clinical recognition, supported by serology, with neuroimaging serving a crucial role in excluding mimics. Approximately one-third of clinically defined BBE cases are seronegative, suggesting alternative mechanisms. Prompt immunotherapy with intravenous immunoglobulin (IVIg) or plasma exchange is the cornerstone of management, extrapolated from GBS trials, while evidence for corticosteroids remains limited. CONCLUSION: A structured, spectrum-based perspective remains essential for clinicians navigating the diagnostic complexities of the anti-GQ1b antibody syndromes. This updated synthesis is intended to enhance diagnostic accuracy, guide therapeutic reasoning across the full range of phenotypes, and highlight key unresolved questions to inform a future research agenda.

Rhombencephalitis is a rare clinical syndrome characterized by inflammation or infection involving the hindbrain, or rhombencephalon. This syndrome is also clinically diverse, with a wide range of etiologies and varying prognoses. The causes of rhombencephalitis include infections, paraneoplastic syndromes, demyelinating disorders, and autoimmune conditions. Neuroimaging, especially MRI, plays an indispensable role in the diagnosis and topographic evaluation of abnormalities. Bacterial rhombencephalitis, particularly that caused by Listeria monocytogenes, commonly affects the dorsal brainstem and proximal cervical spinal cord. Viral rhombencephalitis caused by pathogens such as enterovirus 71 and herpes simplex virus manifests with distinct imaging patterns that aid in differentiating it from other causes. Paraneoplastic rhombencephalitis is associated with malignancies such as small cell lung carcinoma, neuroendocrine tumors, and lymphoma. Demyelinating conditions such as acute disseminated encephalomyelitis, multiple sclerosis, neuromyelitis optica spectrum disorder, and myelin oligodendrocyte glycoprotein antibody-associated disease also demonstrate brainstem involvement with distinctive characteristics. Other uncommon causes of rhombencephalitis include autoimmune diseases such as Bickerstaff brainstem encephalitis and Neuro-Behçet's disease. Understanding these imaging patterns is crucial for timely diagnosis and differentiation of underlying causes, improving patient management and outcomes. This pictorial review provides a comprehensive overview of the imaging characteristics of various causes of rhombencephalitis.

There are numerous autoimmune diseases that present with brainstem involvement including multiple sclerosis, neuromyelitis optica spectrum disorders, myelin oligodendrocyte glycoprotein antibody-associated disease, acute disseminated encephalomyelitis, Bickerstaff brainstem encephalitis, chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS), autoimmune encephalitis/encephalopathy, systemic lupus erythematosus, Sjögren's syndrome, neuro-sarcoidosis, and neuro-Behçet's disease. Symptoms of these diseases depend on the mechanisms, site and extent of the lesions. MRI images and autoantibodies in the blood are useful in diagnosing these diseases. Immunotherapy is the common treatment, though the response to treatment varies from disease to disease. In recent years, biologics have been applied for maintenance therapy.