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Du Q, Huang L, Tang Y, Kang J, Ye W, Feng Z. Median Nerve Stimulation Attenuates Traumatic Brain Injury-Induced Comatose State by Regulating the Orexin-A/RasGRF1 Signaling Pathway. World Neurosurg 2022; 168:e19-e27. [PMID: 36064116 DOI: 10.1016/j.wneu.2022.07.085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/16/2022] [Accepted: 07/18/2022] [Indexed: 01/06/2023]
Abstract
BACKGROUND Despite the arousal effect of median nerve stimulation (MNS) being well documented in the clinical treatment of coma patients with traumatic brain injury (TBI), the mechanisms underlying the observed effect are still not completely understood. This study aimed to evaluate the protective effects and potential mechanism of MNS in comatose rats with TBI. METHODS A total of 60 rats were randomly divided into 5 groups: the control group, sham-stimulated group, MNS group, orexins receptor type 1 (OX1R) antagonist group, and antagonist control group. The free-fall drop method was used to establish a TBI model. After administrating MNS or OX1R antagonist, consciousness was evaluated. Protein levels in the prefrontal cortex were measured using an enzyme-linked immunosorbent assay, Western blotting, and immunofluorescence. RESULTS In the MNS group, tissue damage and consciousness state was markedly improved compared with that in the sham-stimulated group. Administration of the OX1R antagonist attenuated the beneficial effects of MNS in TBI-induced comatose rats. Additionally, MNS also significantly enhanced the expression of orexin-A/OX1R and the activation of Ras guanine nucleotide-releasing factor 1 (RasGRF1). CONCLUSIONS These data show that MNS exerts its wake-promoting effect by activating the OX1R-RasGRF1 pathway in TBI-induced comatose rats.
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Affiliation(s)
- Qing Du
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, People's Republic of China
| | - Lianghua Huang
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, People's Republic of China
| | - Yunliang Tang
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, People's Republic of China
| | - Junwei Kang
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, People's Republic of China
| | - Wen Ye
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, People's Republic of China
| | - Zhen Feng
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, People's Republic of China.
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Liu WP, Wang M, Zhang C, Zhao CW, Xiao B, Zeng C. Application of the APE2-CHN and RITE2-CHN scores for autoimmune seizures and epilepsy in Chinese patients: A retrospective study. Seizure 2020; 81:63-70. [DOI: 10.1016/j.seizure.2020.07.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/07/2020] [Accepted: 07/21/2020] [Indexed: 02/07/2023] Open
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Chen XT, Wang XG, Xie LY, Huang JW, Zhao W, Wang Q, Yao LM, Li WR. Effects of Xingnaojing Injection on Adenosinergic Transmission and Orexin Signaling in Lateral Hypothalamus of Ethanol-Induced Coma Rats. BIOMED RESEARCH INTERNATIONAL 2019; 2019:2389485. [PMID: 31346513 PMCID: PMC6620848 DOI: 10.1155/2019/2389485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 03/08/2019] [Accepted: 03/31/2019] [Indexed: 11/21/2022]
Abstract
Acute alcohol exposure induces unconscious condition such as coma whose main physical manifestation is the loss of righting reflex (LORR). Xingnaojing Injection (XNJI), which came from Chinese classic formula An Gong Niu Huang Pill, is widely used for consciousness disorders in China, such as coma. Although XNJI efficiently shortened the duration of LORR induced by acute ethanol, it remains unknown how XNJI acts on ethanol-induced coma (EIC). We performed experiments to examine the effects of XNJI on orexin and adenosine (AD) signaling in the lateral hypothalamic area (LHA) in EIC rats. Results showed that XNJI reduced the duration of LORR, which implied that XNJI promotes recovery form coma. Microdialysis data indicated that acute ethanol significantly increased AD release in the LHA but had no effect on orexin A levels. The qPCR results displayed a significant reduction in the Orexin-1 receptors (OX1R) expression with a concomitant increase in the A1 receptor (A1R) and equilibrative nucleoside transporter type 1 (ENT1) expression in EIC rats. In contrast, XNJI reduced the extracellular AD levels but orexin A levels remained unaffected. XNJI also counteracted the downregulation of the OX1R expression and upregulation of A1R and ENT1 expression caused by EIC. As for ADK expression, XNJI but not ethanol, displayed an upregulation in the LHA in EIC rats. Based on these results, we suggest that XNJI promotes arousal by inhibiting adenosine neurotransmission via reducing AD level and the expression of A1R and ENT1.
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Affiliation(s)
- Xiao-Tong Chen
- Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, 12 Jichang Road, Baiyun District, Guangzhou 510405, China
| | - Xiao-Ge Wang
- Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, 12 Jichang Road, Baiyun District, Guangzhou 510405, China
| | - Li-Yuan Xie
- Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, 12 Jichang Road, Baiyun District, Guangzhou 510405, China
| | - Jia-Wen Huang
- Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, 12 Jichang Road, Baiyun District, Guangzhou 510405, China
| | - Wei Zhao
- Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, 12 Jichang Road, Baiyun District, Guangzhou 510405, China
| | - Qi Wang
- Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, 12 Jichang Road, Baiyun District, Guangzhou 510405, China
| | - Li-Mei Yao
- School of Traditional Chinese Medicine Healthcare, Guangdong Food and Drug Vocational College, 321 Longdong North Road, Tianhe District, Guangzhou 510520, China
| | - Wei-Rong Li
- Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, 12 Jichang Road, Baiyun District, Guangzhou 510405, China
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Bian H, Huang L, Li B, Hu Q, Liang X, Tang J, Zhang JH. The arousal effect of hyperbaric oxygen through orexin/hypocretin an upregulation on ketamine/ethanol-induced unconsciousness in male rats. J Neurosci Res 2019; 98:201-211. [PMID: 30895638 DOI: 10.1002/jnr.24414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 02/01/2019] [Accepted: 03/01/2019] [Indexed: 01/18/2023]
Abstract
Approaches that facilitate the recovery from coma would have enormous impacts on patient outcomes and medical economics. Orexin-producing neurons release orexins (also known as hypocretins) energy-dependently to maintain arousal. Hyperbaric oxygen (HBO) could increase ATP levels by preserving mitochondrial function. We investigated, for the first time, the arousal effects of HBO and orexins mechanisms in a rat model of unconsciousness induced by ketamine or ethanol. A total of 120 Sprague-Dawley male rats were used in this study. Unconsciousness was induced either by intraperitoneal injection of ketamine or ethanol. The HBO treatment (100% O2 at 3 ATA) was administered immediately after unconsciousness induction for 1 hr. SB334867, orexin-1 receptor (OX1R) inhibitor, or JNJ10397049, orexin-2 receptor (OX2R) inhibitor was administered 30 min intraperitoneally before unconsciousness induction. Loss of righting reflex test (LORR) and Garcia test were used to evaluate the unconsciousness duration and neurological deficits after recovering from unconsciousness, respectively. Enzyme-linked immunosorbent assay was used to measure brain tissue ATP and orexin A levels. Ketamine or ethanol injection resulted in LORR immediately and neurological deficits 6 hr after unconsciousness induction. HBO treatment significantly reduced the LORR duration, improved Garcia scores and unregulated ATP and orexin A levels in the brain tissue. Administration of OX1R inhibitor or OX2 R inhibitor abolished arousal and neurological benefits of HBO. In conclusion, HBO exerted arousal-promoting effects on unconscious rats induced by ketamine or ethanol. The underlying mechanism was via, at least in part, ATP/orexin A upregulation. HBO may be a practical clinical approach to accelerate unconsciousness recovery in patients.
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Affiliation(s)
- Hetao Bian
- Division of Physiology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, California.,Department of Neurology, Jining First People's Hospital, Jining, China.,Mental Health Center of Wuhan University Renmin Hospital, Wuhan, China
| | - Lei Huang
- Division of Physiology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, California.,Department of Neurosurgery, School of Medicine, Loma Linda University, Loma Linda, California
| | - Bo Li
- Division of Physiology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, California
| | - Qin Hu
- Division of Physiology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, California
| | - Xiping Liang
- Division of Physiology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, California
| | - Jiping Tang
- Division of Physiology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, California
| | - John H Zhang
- Division of Physiology, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, California.,Department of Neurosurgery, School of Medicine, Loma Linda University, Loma Linda, California.,Department of Anesthesiology, School of Medicine, Loma Linda University, Loma Linda, California
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Gauci S, Hosking W, Bruck D. Narcolepsy, cataplexy, hypocretin and co-existing other health complaints: A review. COGENT MEDICINE 2017. [DOI: 10.1080/2331205x.2017.1312791] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Affiliation(s)
- Samantha Gauci
- Psychology Discipline, College of Arts, College of Health and Biomedicine, Victoria University, P.O. Box 14428, Melbourne 8001, Australia
| | - Warwick Hosking
- Psychology Discipline, College of Arts, College of Health and Biomedicine, Victoria University, P.O. Box 14428, Melbourne 8001, Australia
| | - Dorothy Bruck
- Psychology Discipline, College of Arts, College of Health and Biomedicine, Victoria University, P.O. Box 14428, Melbourne 8001, Australia
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Olmez I, Moses H, Sriram S, Kirshner H, Lagrange AH, Pawate S. Diagnostic and therapeutic aspects of Hashimoto's encephalopathy. J Neurol Sci 2013; 331:67-71. [PMID: 23759502 DOI: 10.1016/j.jns.2013.05.009] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 04/23/2013] [Accepted: 05/10/2013] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To share our experience on clinical presentation and management of patients diagnosed with Hashimoto's Encephalopathy (HE) at Vanderbilt Medical Center between 1999 and 2012. BACKGROUND HE is a rare disorder characterized by encephalopathy and central nervous system (CNS) dysfunction, elevated antithyroid antibodies, the absence of infection or structural abnormalities in the CNS, and a response to treatment with steroids. The relationship between thyroid antibodies and encephalopathy has remained unresolved. DESIGN/METHODS Retrospective chart review. RESULTS We identified 13 patients who met the criteria for the diagnosis of HE. The median age was 49 years (range, 2-66) and all except one were women. Encephalopathy in the form of altered mental status, stroke-like symptoms or seizures, with prompt resolution of symptoms upon receiving steroids, was the commonest presentation, seen in 7 patients. The second commonest presentation was subacute progressive decrease in cognitive function, which reversed within days to weeks after steroid therapy, seen in 4 patients. Electroencephalogram (EEG) was available in 12 patients and was abnormal in 8, showing nonspecific cerebral dysfunction in all 8 and epileptiform activity in 3. Treatment consisted of steroids in the acute phase for 12 of 13 patients with rapid improvement in symptoms. Maintenance therapy was rituximab in 7 patients, intravenous immunoglobulin (IVIg) in 7, azathioprine in 4, mycophenolate mofetil in 3, and methotrexate in 1 (some patients received sequential therapy with different agents). There was complete or near complete resolution of symptoms in 12 of the 13 patients. CONCLUSIONS We present a cohort of patients in whom CNS dysfunction was associated with elevated antithyroid antibodies and reversal of disease followed immunomodulatory therapies.
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Affiliation(s)
- Inan Olmez
- Vanderbilt University, Department of Neurology, Nashville, TN 37232, USA
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8
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Encéphalopathie d’Hashimoto. Rev Med Interne 2012; 33:390-5. [DOI: 10.1016/j.revmed.2012.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Revised: 01/28/2012] [Accepted: 02/22/2012] [Indexed: 11/21/2022]
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von Geldern G, McPharlin T, Becker K. Immune mediated diseases and immune modulation in the neurocritical care unit. Neurotherapeutics 2012; 9:99-123. [PMID: 22161307 PMCID: PMC3271148 DOI: 10.1007/s13311-011-0096-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
This chapter will review the spectrum of immune-mediated diseases that affect the nervous system and may result in an admission to the neurological intensive care unit. Immunomodulatory strategies to treat acute exacerbations of neurological diseases caused by aberrant immune responses are discussed, but strategies for long-term immunosuppression are not presented. The recommendations for therapeutic intervention are based on a synthesis of the literature, and include recommendations by the Cochrane Collaborative, the American Academy of Neurology, and other key organizations. References from recent publications are provided for the disorders and therapies in which randomized clinical trials and large evidenced-based reviews do not exist. The chapter concludes with a brief review of the mechanisms of action, dosing, and side effects of commonly used immunosuppressive strategies in the neurocritical care unit.
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Affiliation(s)
- Gloria von Geldern
- Department of Neurology, Johns Hopkins School of Medicine, Baltimore, MD 21287 USA
| | - Thomas McPharlin
- University of Washington School of Pharmacy, Seattle, WA 98104 USA
| | - Kyra Becker
- Department of Neurology, University of Washington School of Medicine, Seattle, WA 98104 USA
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10
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Jia X, Yan J, Xia J, Xiong J, Wang T, Chen Y, Qi A, Yang N, Fan S, Ye J, Hu Z. Arousal effects of orexin A on acute alcohol intoxication-induced coma in rats. Neuropharmacology 2011; 62:775-83. [PMID: 21924278 DOI: 10.1016/j.neuropharm.2011.08.047] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 08/24/2011] [Accepted: 08/28/2011] [Indexed: 11/25/2022]
Abstract
The key role of the hypothalamic neuropeptides orexins in maintenance and promotion of arousal has been well established in normal mammalian animals, but whether orexins exert arousal effects under pathological condition such as coma was little studied. In this study, a model of unconscious rats induced by acute alcohol intoxication was used to examine the effects of orexins through intracerebroventricular injection. The results revealed that either orexin A or orexin B induced decrease of duration of loss of right reflex in alcohol-induced unconscious rats. In the presence of the selective orexin receptor 1 antagonist SB 334867 and orexin receptor 2 antagonist TCS OX2 29, the excitatory action of orexin A was completely blocked. Our data further presented that orexin A also induced reduction of delta power in EEG in these rats. Single-unit recording experiment in vivo demonstrated that orexin A could evoke increase of firing activity of prefrontal cortex neurons in unconscious rats. This excitation was completely inhibited by an H(1) receptor antagonist, pyrilamine, whereas application of α(1)-adrenoreceptor antagonist prazosin or 5-HT(2) selective receptor antagonist ritanserin partially attenuated the excitatory effects of orexin A on these neurons. Consistently, the results of EEG recordings showed that microinjection of pyrilamine, prazosin, or ritanserin suppressed reduction of delta power in EEG induced by orexin A on unconscious rats. Thus, these data suggest that orexins exert arousal effects on alcohol-induced unconscious rats by the promotion of cortical activity through activation of histaminergic, noradrenergic and serotonergic systems. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.
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Affiliation(s)
- Xiaojun Jia
- Department of Physiology, Third Military Medical University, Chongqing 400038, PR China
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11
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Abstract
Hashimoto's encephalopathy (HE) is a controversial neurological disorder that comprises a heterogenous group of neurological symptoms that manifest in patients with high titers of antithyroid antibodies. Clinical manifestations of HE may include encephalopathic features such as seizures, behavioral and psychiatric manifestations, movement disorders, and coma. Although it has been linked to cases of Hashimoto's thyroiditis or thyroid dysfunction, the most common immunological feature of HE is the presence of high titers of antithyroglobulin or anti-TPO (antimicrosomal) antibodies. At present, it is unclear whether antithyroid antibodies represent an immune epiphenomenon in a subset of patients with encephalopathic processes or they are really associated with pathogenic mechanisms of the disorder. The significance of classifying encephalopathies under the term HE will be determined in the future once the relevance of the role of antithyroid antibodies is demonstrated or dismissed by more detailed experimental and immunopathological studies. The responsiveness of HE to steroids or other therapies such as plasmapheresis supports the hypothesis that this is a disorder that involves immune pathogenic mechanisms. Further controlled studies of the use of steroids, plasmapheresis, or immunosuppressant medications are needed in the future to prove the concept of the pathogenic role of antithyroid antibodies in HE.
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Affiliation(s)
- Nicoline Schiess
- Department of Neurology, Division of Neuroimmunology and Neuroinfectious Disorders, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
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Ferracci F, Carnevale A. The neurological disorder associated with thyroid autoimmunity. J Neurol 2006; 253:975-84. [PMID: 16786216 DOI: 10.1007/s00415-006-0170-7] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Accepted: 01/30/2006] [Indexed: 01/18/2023]
Abstract
The neurological disorder associated with thyroid autoimmunity is an elusive disease that neurologists have learned to recognize in the last few years. The diagnosis is made, after excluding more common diseases, when neuropsychiatric symptoms develop in a patient with high serum concentrations of anti-thyroid antibodies. The clinical presentations of the disease and the many controversial issues surrounding the diagnosis, the pathogenesis, the role of thyroid autoantibodies, and the choice of therapy are reviewed and discussed in the light of the medical literature in English.
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Affiliation(s)
- Franco Ferracci
- Divisione di Neurologia, Ospedale San Martino, Viale Europa, 32100 Belluno, Italy.
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13
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Tamagno G, Federspil G, Murialdo G. Clinical and diagnostic aspects of encephalopathy associated with autoimmune thyroid disease (or Hashimoto's encephalopathy). Intern Emerg Med 2006; 1:15-23. [PMID: 16941808 DOI: 10.1007/bf02934715] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Encephalopathy associated with autoimmune thyroid disease, currently known as Hashimoto's encephalopathy, but also defined as corticosteroid-responsive encephalopathy associated with autoimmune thyroiditis, is a relatively rare condition observed in a small percentage of patients presenting with autoimmune thyroid disease. It consists of a subacute, relapsing-remitting, steroid-responsive encephalopathy characterised by protean neurologic and neuropsychiatric symptoms, diffuse electroencephalographic abnormalities and increased titres of antithyroid antibodies in serum and/or in cerebrospinal fluid. Most of the cases presenting this neurologic complication are affected by Hashimoto's thyroiditis or, less frequently, by other autoimmune thyroid diseases, chiefly Graves' disease. The pathogenesis of this encephalopathy is still unknown and largely debated, because of extremely varied clinical presentation, possibly referable to different aetiologic and pathophysiologic mechanisms, as confirmed by the two clinical cases we report in this paper. Autoimmune aetiology is, however, very likely in view of the well established favourable response to corticosteroid administration. Both vasculitis and autoimmunity directed against common brain-thyroid antigens represent the most probable aetiologic pathways. Clinical manifestations include consciousness changes, neurologic diffuse or focal signs, headache, and altered cognitive function. Although unspecific, cerebral oedema has also been described. Cerebrospinal fluid examination often discloses an inflammatory process, with a mild increase in protein content and occasionally in lymphocyte count. In this review, clinical criteria for the diagnosis of defined, probable, or possible encephalopathy associated with autoimmune thyroid disease are suggested. Corticosteroid therapy currently allows us to obtain rapid remission of disease symptoms, but adverse outcomes as well as spontaneous remissions have also been reported.
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Affiliation(s)
- Gianluca Tamagno
- Medical Clinic 3, Department of Medical and Surgical Sciences, University of Padua, Padua, Italy
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Martínez-Rodríguez JE, Santamaria J. CSF markers in sleep neurobiology. Clin Chim Acta 2005; 362:12-25. [PMID: 15992787 DOI: 10.1016/j.cccn.2005.05.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2005] [Revised: 05/23/2005] [Accepted: 05/24/2005] [Indexed: 11/19/2022]
Abstract
The cerebrospinal fluid has been used in the study of normal and pathological conditions of the central nervous system for more than a century. CSF analysis has also been applied to the study of sleep and its disorders but methodological aspects have often limited the results. The discovery of the hypocretin system (also known as orexin system) and its involvement in the pathophysiology of narcolepsy has opened a new field in the diagnosis of hypersomnia by CSF analysis and has revived the interest on this subject in sleep medicine. Older and new lines of research involving CSF measurement of hypocretin and other neurotransmitters in sleep and its disorders are reviewed.
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Affiliation(s)
- Jose E Martínez-Rodríguez
- Neurology Service, Hospital Clínic de Barcelona and Institut d'Investigació Biomédica August Pi i Sunyer (IDIBAPS), C/Villarroel 170, Spain.
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Abstract
The hypocretins (also called the orexins) are two neuropeptides derived from the same precursor whose expression is restricted to a few thousand neurons of the lateral hypothalamus. Two G-protein coupled receptors for the hypocretins have been identified, and these show different distributions within the central nervous system and differential affinities for the two hypocretins. Hypocretin fibers project throughout the brain, including several areas implicated in regulation of the sleep/wakefulness cycle. Central administration of synthetic hypocretin-1 affects blood pressure, hormone secretion and locomotor activity, and increases wakefulness while suppressing rapid eye movement sleep. Most human patients with narcolepsy have greatly reduced levels of hypocretin peptides in their cerebral spinal fluid and no or barely detectable hypocretin-containing neurons in their hypothalamus. Multiple lines of evidence suggest that the hypocretinergic system integrates homeostatic, metabolic and limbic information and provides a coherent output that results in stability of the states of vigilance.
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Affiliation(s)
- Luis de Lecea
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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16
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Abstract
Since their discovery in 1998, the hypocretins (orexins)-peptides that are produced by a group of neurons situated in the posterolateral hypothalamus--have been shown to excite many CNS areas including many neuronal systems that regulate sleep and wakefulness. Animal studies indicate that hypocretins play a part in the regulation of various functions including arousal, muscle tone, locomotion, regulation of feeding behaviour, and neuroendocrine and autonomic functions. A link between hypocretin deficiency and narcoleptic symptoms was first shown in canine and rodent models of narcolepsy. Hypocretin deficiency, as shown by low or absent concentrations in CSF, was subsequently found in 90% of patients with sporadic narcolepsy-cataplexy, and less commonly in familial narcolepsy. In most other sleep-wake and neurological disorders, hypocretin concentrations are normal. Low concentrations were also found in hypothalamic disorders, acute traumatic brain injury, and a few other disorders. The exact function of the hypocretin system in sleep-wake regulation and its pathophysiological role in hypocretin-deficient and non-deficient narcolepsy as well as in non-narcoleptic, hypocretin-deficiency syndromes remain unclear.
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Affiliation(s)
- Christian R Baumann
- Department of Neurology, University Hospital, Frauenklinikstrasse 26, 8091 Zürich, Switzerland
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Baumann CR, Bassetti CL. Hypocretins (orexins): clinical impact of the discovery of a neurotransmitter. Sleep Med Rev 2005; 9:253-68. [PMID: 15979356 DOI: 10.1016/j.smrv.2005.01.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Hypothalamic excitatory hypocretin (orexin) neurons have been discovered in 1998 and found to have widespread projections to basal forebrain, monoaminergic and cholinergic brainstem, and spinal cord regions. The hypocretin system is influenced both neuronally (e.g. suprachiasmatic nucleus, GABAergic, cholinergic and aminergic brainstem nuclei) as well as metabolically (e.g. glucose, ghrelin, and leptin). Physiologically the hypocretin system has been implicated in the regulation of behaviours that are associated with wakefulness, locomotion, and feeding. A role in REM sleep, neuroendocrine, autonomic and metabolic functions has also been suggested. Pathophysiologically a deficient hypocretin neurotransmission has been found in human narcolepsy and (engineered) animal models of the disorder. Different mechanisms are involved including (1) degeneration of hypocretin neurons (mice), (2) hypocretin ligand deficiency (humans, mice, dogs), (3) hypocretin receptor deficiency (mice, dogs). Reports of low hypocretin-1 cerebrospinal fluid levels in neurologic conditions (e.g. Guillain-Barré syndrome, traumatic brain injury, hypothalamic lesions) with and without sleep-wake disturbances and, on the other hand, observations of normal levels in about 11% of narcoleptics raise questions about the exact nature and pathophysiological base of the link between hypocretin deficiency and clinical manifestations in human narcolepsy.
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Affiliation(s)
- Christian R Baumann
- Neurologische Klinik, Universitätsspital Zürich, Frauenklinikstrasse 26, CH-8091 Zürich, Switzerland
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Nishino S, Kanbayashi T. Symptomatic narcolepsy, cataplexy and hypersomnia, and their implications in the hypothalamic hypocretin/orexin system. Sleep Med Rev 2005; 9:269-310. [PMID: 16006155 DOI: 10.1016/j.smrv.2005.03.004] [Citation(s) in RCA: 184] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Human narcolepsy is a chronic sleep disorder affecting 1:2000 individuals. The disease is characterized by excessive daytime sleepiness, cataplexy and other abnormal manifestations of REM sleep, such as sleep paralysis and hypnagogic hallucinations. Recently, it was discovered that the pathophysiology of (idiopathic) narcolepsy-cataplexy is linked to hypocretin ligand deficiency in the brain and cerebrospinal fluid (CSF), as well as the positivity of the human leukocyte antigen (HLA) DR2/DQ6 (DQB1*0602). The symptoms of narcolepsy can also occur during the course of other neurological conditions (i.e. symptomatic narcolepsy). We define symptomatic narcolepsy as those cases that meet the International Sleep Disorders Narcolepsy Criteria, and which are also associated with a significant underlying neurological disorder that accounts for excessive daytime sleepiness (EDS) and temporal associations. To date, we have counted 116 symptomatic cases of narcolepsy reported in literature. As, several authors previously reported, inherited disorders (n=38), tumors (n=33), and head trauma (n=19) are the three most frequent causes for symptomatic narcolepsy. Of the 116 cases, 10 are associated with multiple sclerosis, one case of acute disseminated encephalomyelitis, and relatively rare cases were reported with vascular disorders (n=6), encephalitis (n=4) and degeneration (n=1), and hererodegenerative disorder (three cases in a family). EDS without cataplexy or any REM sleep abnormalities is also often associated with these neurological conditions, and defined as symptomatic cases of EDS. Although it is difficult to rule out the comorbidity of idiopathic narcolepsy in some cases, review of the literature reveals numerous unquestionable cases of symptomatic narcolepsy. These include cases with HLA negative and/or late onset, and cases in which the occurrences of the narcoleptic symptoms are parallel with the rise and fall of the causative disease. A review of these cases (especially those with brain tumors), illustrates a clear picture that the hypothalamus is most often involved. Several cases of symptomatic cataplexy (without EDS) were also reported and in contrast, these cases appear to be often associated with non-hypothalamic structures. CSF hypocretin-1 measurement were also carried out in a limited number of symptomatic cases of narcolepsy/EDS, including narcolepsy/EDS associated with tumors (n=5), head trauma (n=3), vascular disorders (n=5), encephalopathies (n=3), degeneration (n=30), demyelinating disorder (n=7), genetic/congenital disorders (n=11) and others (n=2). Reduced CSF hypocretin-1 levels were seen in most symptomatic narcolepsy cases of EDS with various etiologies and EDS in these cases is sometimes reversible with an improvement of the causative neurological disorder and an improvement of the hypocretin status. It is also noted that some symptomatic EDS cases (with Parkinson diseases and the thalamic infarction) appeared, but they are not linked with hypocretin ligand deficiency. In contrast to idiopathic narcolepsy cases, an occurrence of cataplexy is not tightly associated with hypocretin ligand deficiency in symptomatic cases. Since CSF hypocretin measures are still experimental, cases with sleep abnormalities/cataplexy are habitually selected for CSF hypocretin measures. Therefore, it is still not known whether all or a large majority of cases with low CSF hypocretin-1 levels with CNS interventions, exhibit EDS/cataplexy. It appears that further studies of the involvement of the hypocretin system in symptomatic narcolepsy and EDS are helpful to understand the pathophysiological mechanisms for the occurrence of EDS and cataplexy.
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Affiliation(s)
- Seiji Nishino
- Center for Narcolepsy, Stanford University, Palo Alto, CA 94304, USA.
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Fatourechi V. Hashimoto's encephalopathy: myth or reality? An endocrinologist's perspective. Best Pract Res Clin Endocrinol Metab 2005; 19:53-66. [PMID: 15826922 DOI: 10.1016/j.beem.2004.11.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Since the first description of a case of episodic encephalopathy associated with Hashimoto's thyroiditis in 1966, many cases of corticosteroid-responsive encephalopathy associated with positive antithyroid antibodies, clinical Hashimoto's thyroiditis, or spontaneous autoimmune thyroid failure have been reported. These patients have neurologic manifestations of encephalopathy unrelated to other known causes. The condition has thus been termed 'Hashimoto's encephalopathy'. The literature shows no proven association between thyroid disease and the neurologic process. Although the association of a common endocrinologic condition and a rare neurologic disease may occur by chance, this type of encephalopathy probably has an autoimmune nature and thus is more likely to occur in the background of another autoimmune condition such as autoimmune thyroid disease. Until the pathogenesis of these coincident conditions is better defined, the term 'corticosteroid-responsive encephalopathy associated with autoimmune thyroiditis' is more accurate and descriptive than Hashimoto's encephalopathy. Advances in the field may clarify this seemingly inconsistent terminology.
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Affiliation(s)
- Vahab Fatourechi
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Mayo Clinic College of Medicine, Rochester, MN, USA.
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