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Journal of Intensive Care Medicine Oct 2016Criteria for establishing brain death (BD) require absence of all brainstem-mediated reflexes including motor (ie, decerebrate or decorticate) posturing. A number of... (Review)
Review
INTRODUCTION
Criteria for establishing brain death (BD) require absence of all brainstem-mediated reflexes including motor (ie, decerebrate or decorticate) posturing. A number of spinal cord automatisms may emerge after BD, but occurrence of decerebrate-like spinal reflexes may be particularly problematic; confusion of such stereotypic extension-pronation movements with brain stem reflexes may confound or delay definitive diagnosis of BD. We present a case in which we verified the noncerebral (ie, likely spinal) origin of such decerebrate-like reflexes.
METHODS
Case report and systematic review of literature.
RESULTS
A 63-year-old woman presented with large pontine hemorrhage and complete loss of cerebral function, including no motor response to pain. Apnea testing confirmed death by neurologic criteria. Thirty-six hours after BD declaration, during assessment for organ donation, she began to exhibit spontaneous and stimulus-induced stereotypic extension-pronation of the upper extremities. The similarity of these movements to decerebrate posturing prompted concern for retained brain stem function, but repeat neurological examination of cranial nerves and apnea testing did not reveal any cerebral responses. Electrocerebral silence on electroencephalogram and absent perfusion on nuclear medicine brain imaging further confirmed BD. Review of PubMed yielded 5 additional case reports and 4 cohorts describing cases of decerebrate-like extension-pronation movements presenting in a delayed fashion after BD.
CONCLUSION
Extension-pronation movements that mimic decerebrate posturing may be seen in a delayed fashion after BD. Verification of lack of any brain activity (by both examination and multiple ancillary tests) in this case and others prompts us to attribute these movements as spinal cord reflexes and propose they be recognized within the rubric of accepted post-BD automatisms that should not delay diagnosis or necessitate confirmatory testing.
Topics: Brain Death; Brain Stem; Decerebrate State; Electroencephalography; Female; Humans; Middle Aged; Muscle Contraction; Neurologic Examination; Spinal Nerves; Tissue and Organ Procurement
PubMed: 27170657
DOI: 10.1177/0885066616646076 -
American Journal of Physiology.... May 2019Recent findings have shown that muscle contraction evokes an exaggerated pressor response in type 1 diabetes mellitus (T1DM) rats; however, it is not known whether the...
Recent findings have shown that muscle contraction evokes an exaggerated pressor response in type 1 diabetes mellitus (T1DM) rats; however, it is not known whether the mechanoreflex, which is commonly stimulated by stretching the Achilles tendon, contributes to this abnormal response. Furthermore, the role of mechano-gated Piezo channels, found on thin-fiber afferent endings, in evoking the mechanoreflex in T1DM is also unknown. Therefore, in male and female streptozotocin (STZ, 50 mg/kg)-induced T1DM and healthy control (CTL) rats, we examined the pressor and cardioaccelerator responses to tendon stretch during the early stage of the disease. To determine the role of Piezo channels, GsMTx-4, a selective Piezo channel inhibitor, was injected into the arterial supply of the hindlimb. At 1 wk after STZ injection in anesthetized, decerebrate rats, we stretched the Achilles tendon for 30 s and measured pressor and cardioaccelerator responses. We then compared pressor and cardioaccelerator responses to tendon stretch before and after GsMTx-4 injection (10 µg/100 ml). We found that the pressor (change in mean arterial pressure) response [41 ± 5 mmHg ( = 15) for STZ and 18 ± 3 mmHg ( = 11) for CTL ( < 0.01)] and cardioaccelerator (change in heart rate) response [18 ± 4 beats/min for STZ ( = 15) and 8 ± 2 beats/min ( = 11) for CTL ( < 0.05)] to tendon stretch were exaggerated in STZ rats. Local injection of GsMTx-4 attenuated the pressor [55 ± 7 mmHg ( = 6) before and 27 ± 9 mmHg ( = 6) after GsMTx-4 ( < 0.01)], but not the cardioaccelerator, response to tendon stretch in STZ rats and had no effect on either response in CTL rats. These data suggest that T1DM exaggerates the mechanoreflex response to tendon stretch and that Piezo channels play a role in this exaggeration.
Topics: Animals; Blood Pressure; Decerebrate State; Diabetes Mellitus, Experimental; Female; Hindlimb; Intercellular Signaling Peptides and Proteins; Male; Muscle Contraction; Muscle, Skeletal; Physical Conditioning, Animal; Rats, Sprague-Dawley; Reflex; Spider Venoms
PubMed: 30840487
DOI: 10.1152/ajpregu.00294.2018 -
American Journal of Physiology. Heart... Oct 2017Previous studies have shown that diabetic peripheral neuropathy affects both unmyelinated and myelinated afferents, similar to those evoking the exercise pressor reflex....
Previous studies have shown that diabetic peripheral neuropathy affects both unmyelinated and myelinated afferents, similar to those evoking the exercise pressor reflex. However, the effect of type 1 diabetes (T1DM) on this reflex is not known. We examined, in decerebrate male and female T1DM [streptozotocin (STZ)] and healthy control (CTL) rats, pressor and cardioaccelerator responses to isometric contraction of the hindlimb muscles during the early and late stages of the disease. STZ (50 mg/kg) was injected to induce diabetes, and experiments were conducted at 1, 3, and 6 wk after injection. On the day of the experiment, we statically contracted the hindlimb muscles by stimulating the sciatic nerve and measured changes in mean arterial pressure and heart rate. We found that the pressor but not cardioaccelerator response was exaggerated in STZ rats at 1 wk (STZ: 21 ± 3 mmHg, = 10, and CTL: 14 ± 2 mmHg, = 10, < 0.05) and at 3 wk (STZ: 26 ± 5 mmHg, = 10, and CTL: 17 ± 3 mmHg, = 11, < 0.05) after injection. However, at 6 wk, and only in male rats, both the pressor (STZ: 13 ± 3 mmHg, = 12, and CTL: 17 ± 3 mmHg, = 13, < 0.05) and cardioaccelerator responses (STZ: 7 ± 3 beats/min, = 12, and CTL: 10 ± 3 beats/min, = 13, < 0.05) to contraction were significantly attenuated in STZ rats compared with CTL rats. These data indicate that T1DM exaggerates the exercise pressor reflex during the early stages of the disease in both male and female rats. Conversely, T1DM attenuates this reflex in the late stage of the disease in male but not female rats. This is the first study to provide evidence that the pressor and cardioaccelerator responses to skeletal muscle contraction vary depending on the duration of type 1 diabetes.
Topics: Animals; Arterial Pressure; Case-Control Studies; Decerebrate State; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Electric Stimulation; Female; Heart Rate; Hindlimb; Male; Muscle Contraction; Muscle, Skeletal; Physical Conditioning, Animal; Rats; Rats, Sprague-Dawley; Reflex; Reflex, Abnormal; Sciatic Nerve; Sex Factors; Vasoconstriction
PubMed: 28778915
DOI: 10.1152/ajpheart.00399.2017 -
The Neurodiagnostic Journal Mar 2020A severe and unusual complication found in children with influenza is an acute necrotizing encephalopathy. A 20-month-old female with no significant past medical history...
A severe and unusual complication found in children with influenza is an acute necrotizing encephalopathy. A 20-month-old female with no significant past medical history was admitted to our facility, presenting with a 4-day history of worsening fever, upper respiratory symptoms, new-onset altered mental status and episodes of extensor posturing. The initial concern was a dystonic reaction secondary to promethazine following a recent diagnosis of influenza A virus. A head computed tomography scan indicated concern for widespread edema, and the video EEG revealed focal slowing in the frontocentral regions with no epileptiform activity during episodes of extensor posturing. The first magnetic resonance imaging results were consistent with acute hemorrhagic encephalitis or severe anoxic brain injury for which there is a broad differential. A second MRI five days later found new areas of restricted diffusion that were consistent with acute necrotizing encephalitis.
Topics: Brain; Decerebrate State; Electroencephalography; Female; Humans; Infant; Influenza A virus; Influenza, Human; Leukoencephalitis, Acute Hemorrhagic; Magnetic Resonance Imaging
PubMed: 32101112
DOI: 10.1080/21646821.2020.1725864 -
Frontiers in Neural Circuits 2020: The spinal cord's central pattern generators (CPGs) have been explained by the symmetrical half-center hypothesis, the bursts generator, computational models, and more...
: The spinal cord's central pattern generators (CPGs) have been explained by the symmetrical half-center hypothesis, the bursts generator, computational models, and more recently by connectome circuits. Asymmetrical models, at odds with the half-center paradigm, are composed of extensor and flexor CPG modules. Other models include not only flexor and extensor motoneurons but also motoneuron pools controlling biarticular muscles. It is unknown whether a preferred model can explain some particularities that fictive scratching (FS) in the cat presents. The first aim of this study was to investigate FS patterns considering the aiming and the rhythmic periods, and second, to examine the effects of serotonin (5HT) on and segmental inputs to FS. : The experiments were carried out first in brain cortex-ablated cats (BCAC), then spinalized (SC), and for the midcollicular (MCC) preparation. Subjects were immobilized and the peripheral nerves were used to elicit the Monosynaptic reflex (MR), to modify the scratching patterns and for electroneurogram recordings. : In BCAC, FS was produced by pinna stimulation and, in some cases, by serotonin. The scratching aiming phase (AP) initiates with the activation of either flexor or extensor motoneurons. Serotonin application during the AP produced simultaneous extensor and flexor bursts. Furthermore, WAY 100635 (5HT1A antagonist) produced a brief burst in the tibialis anterior (TA) nerve, followed by a reduction in its electroneurogram (ENG), while the soleus ENG remained silent. In SC, rhythmic phase (RP) activity was recorded in the soleus motoneurons. Serotonin or WAY produced FS bouts. The electrical stimulation of Ia afferent fibers produced heteronymous MRes waxing and waning during the scratch cycle. In MCC, FS began with flexor activity. Electrical stimulation of either deep peroneus (DP) or superficial peroneus (SP) nerves increased the duration of the TA electroneurogram. Medial gastrocnemius (MG) stretching or MG nerve electrical stimulation produced a reduction in the TA electroneurogram and an initial MG extensor burst. MRes waxed and waned during the scratch cycle. : Descending pathways and segmental afferent fibers, as well as 5-HT and WAY, can change the FS pattern. To our understanding, the half-center hypothesis is the most suitable for explaining the AP in MCC.
Topics: Ablation Techniques; Animals; Brain; Cats; Cerebral Cortex; Decerebrate State; Electric Stimulation; Motor Neurons; Peripheral Nerves; Reflex, Monosynaptic; Serotonin; Serotonin Antagonists; Spinal Cord; Superior Colliculi
PubMed: 32174815
DOI: 10.3389/fncir.2020.00001 -
Frontiers in Neuroscience 2017Sympathetic nerve activity (SNA) contributes appreciably to the control of physiological function, such that pathological alterations in SNA can lead to a variety of... (Review)
Review
Sympathetic nerve activity (SNA) contributes appreciably to the control of physiological function, such that pathological alterations in SNA can lead to a variety of diseases. The goal of this review is to discuss the characteristics of SNA, briefly review the methodology that has been used to assess SNA and its control, and to describe the essential role of neurophysiological studies in conscious animals to provide additional insights into the regulation of SNA. Studies in both humans and animals have shown that SNA is rhythmic or organized into bursts whose frequency varies depending on experimental conditions and the species. These rhythms are generated by brainstem neurons, and conveyed to sympathetic preganglionic neurons through several pathways, including those emanating from the rostral ventrolateral medulla. Although rhythmic SNA is present in decerebrate animals (indicating that neurons in the brainstem and spinal cord are adequate to generate this activity), there is considerable evidence that a variety of supratentorial structures including the insular and prefrontal cortices, amygdala, and hypothalamic subnuclei provide inputs to the brainstem regions that regulate SNA. It is also known that the characteristics of SNA are altered during stress and particular behaviors such as the defense response and exercise. While it is a certainty that supratentorial structures contribute to changes in SNA during these behaviors, the neural underpinnings of the responses are yet to be established. Understanding how SNA is modified during affective responses and particular behaviors will require neurophysiological studies in awake, behaving animals, including those that entail recording activity from neurons that generate SNA. Recent studies have shown that responses of neurons in the central nervous system to most sensory inputs are context-specific. Future neurophysiological studies in conscious animals should also ascertain whether this general rule also applies to sensory signals that modify SNA.
PubMed: 29311801
DOI: 10.3389/fnins.2017.00730 -
Journal of Clinical and Diagnostic... Jul 2016Malaria is the most important parasitic disease of humans causes clinical illness over 300-500 million people globally and over one million death every year globally....
INTRODUCTION
Malaria is the most important parasitic disease of humans causes clinical illness over 300-500 million people globally and over one million death every year globally. The involvement of the nervous system in malaria is studied in this paper, to help formulate a strategy for better malaria management.
AIM
To study the Neuropsychiatric manifestation in malaria.
MATERIALS AND METHODS
This was a prospective observational study in 170 patients with a clinical diagnosis of malaria admitted in various medical wards of medicine department of PBM Hospital, Bikaner during epidemic of malaria. It included both sexes of all age groups except the paediatric range. The diagnosis of malaria was confirmed by examination of thick and thin smear/optimal test/strip test. Only those cases that had asexual form of parasite of malaria in the blood by smear examination or optimal test were included in the study.
RESULTS
Out of total 170 patients 104 (62%) reported Plasmodium falciparum (PF), Plasmodium vivax (PV) were 57 (33.5%) followed by mixed (PF+PV) 9 (5.3%) cases. The total PBF-MP test positivity was 84.5%. Maximum patients were belonging to the age range of 21-40 year with male predominance. Neuropsychiatric manifestation seen in falciparum malaria (n=111) as follow: altered consciousness 20 (18.01%), headache 17 (15.32%), neck rigidity 5 (4.5%), convulsion 5 (4.55%), extra pyramidal rigidity 2 (1.8%), decorticate rigidity 1 (0.90%), decerebrate rigidity 1 (0.90%), cerebellar ataxia 3 (2.7%), subarachnoid haemorrhage 1 (0.90%), aphasia 2 (1.8%), subconjunctival haemorrhage 1 (0.90%), conjugate deviation of eye 1 (0.90%) and psychosis 6 (5.40%). Twenty one patients presented with cerebral malaria out of 111 patients. Most patients of cerebral malaria presented with altered level of consciousness followed by headache and psychosis. Acute confusional state with clouding of consciousness was the most common presentation of psychosis (50%).
CONCLUSION
Neuropsychiatric manifestations are not an uncommon presentation of malaria. Most commonly caused by PF malaria. Malaria should be thought as a differential diagnosis in pyrexia with neuropsychiatric manifestation. Observation obtained in the study will be highly useful for the diagnosis and management of patients suffering from malaria.
PubMed: 27630883
DOI: 10.7860/JCDR/2016/19035.8169 -
Journal of Vascular Research 2020Palmitoylethanolamide is an endogenous lipid that exerts complex vascular effects, enhances the effects of endocannabinoids and induces a direct hypotension, but the...
Palmitoylethanolamide is an endogenous lipid that exerts complex vascular effects, enhances the effects of endocannabinoids and induces a direct hypotension, but the mechanisms involved have been poorly explored. Hence, this study investigated in Wistar pithed rats the role of CB1, CB2, TRPV1 and GPR55 receptors in the inhibition by palmitoylethanolamide of the vasopressor responses produced by sympathetic stimulation or exogenous noradrenaline. Frequency- and dose-dependent vasopressor responses were analysed before and during intravenous (i.v.) continuous infusions of palmitoylethanolamide in animals receiving i.v. bolus of the antagonists NIDA41020 (CB1), AM630 (CB2), capsazepine (TRPV1), and/or cannabidiol (GPR55). Palmitoyletha-nolamide (0.1-3.1 μg/kg/min) dose-dependently inhibited the sympathetically induced and noradrenaline-induced vasopressor responses. Both inhibitions were: (i) partially blocked by 100 μg/kg NIDA41020, 100 μg/kg capsazepine, or 31 μg/kg cannabidiol; (ii) unaffected by 310 μg/kg AM630; and (iii) abolished by the combination NIDA41020 + capsazepine + cannabidiol (100, 100, and 31 μg/kg, respectively). The resting blood pressure was decreased by palmitoylethanolamide (effect prevented by NIDA41020, capsazepine or cannabidiol, but not by AM630). These results suggest that: (i) palmitoylethanolamide inhibits the vasopressor responses to sympathetic stimulation and exogenous noradrenaline and that it induces hypotension; and (ii) all these effects are mediated by prejunctional and vascular CB1, TRPV1 and probably GPR55, but not by CB2, receptors.
Topics: Amides; Animals; Arteries; Decerebrate State; Electric Stimulation; Ethanolamines; Male; Norepinephrine; Palmitic Acids; Rats, Wistar; Receptor, Cannabinoid, CB1; Receptors, Cannabinoid; Receptors, G-Protein-Coupled; Signal Transduction; Sympathetic Nervous System; Sympathomimetics; TRPV Cation Channels; Vasodilation; Vasodilator Agents
PubMed: 32248195
DOI: 10.1159/000506158 -
American Journal of Physiology. Heart... Aug 2023Stimulation of mechanically sensitive channels on the sensory endings of group III and IV thin fiber muscle afferents activates the mechanoreflex, which contributes to...
Stimulation of mechanically sensitive channels on the sensory endings of group III and IV thin fiber muscle afferents activates the mechanoreflex, which contributes to reflex increases in sympathetic nerve activity (SNA) and blood pressure during exercise. Accumulating evidence suggests that activation of the nonselective cation channel transient receptor potential vanilloid-1 (TRPV1) on the sensory endings of thin fiber afferents with capsaicin may attenuate mechanosensation. However, no study has investigated the effect of capsaicin on the mechanoreflex. We tested the hypothesis that in male and female decerebrate, unanesthetized rats, the injection of capsaicin (0.05 µg) into the arterial supply of the hindlimb reduces the pressor and renal SNA (RSNA) response to 30 s of 1 Hz rhythmic hindlimb muscle stretch (a model of isolated mechanoreflex activation). In male rats ( = 8), capsaicin injection significantly reduced the integrated blood pressure (blood pressure index or BPI: pre, 363 ± 78; post, 211 ± 88 mmHg·s; = 0.023) and RSNA [∫ΔRSNA; pre, 687 ± 206; post, 216 ± 80 arbitrary units (au), = 0.049] response to hindlimb muscle stretch. In female rats ( = 8), capsaicin injection had no significant effect on the pressor (BPI; pre: 277 ± 67; post: 207 ± 77 mmHg·s; = 0.343) or RSNA (∫ΔRSNA: pre, 697 ± 123; post, 440 ± 183 au; = 0.307) response to hindlimb muscle stretch. The data suggest that the injection of capsaicin into the hindlimb arterial supply to stimulate TRPV1 on the sensory endings of thin fiber muscle afferents attenuates the mechanoreflex in healthy male, but not female, rats. The findings may carry important implications for chronic conditions in which an exaggerated mechanoreflex contributes to aberrant sympathoexcitation during exercise. Recent evidence in isolated sensory neurons indicates that capsaicin-induced stimulation of TRPV1 attenuates mechanosensitivity. Here we demonstrate for the first time that capsaicin exposure/administration reduces the reflex pressor and renal sympathetic nerve response to mechanoreflex activation in male rats, but not female rats, in vivo. Our data may carry important clinical implications for chronic diseases which have been linked to an exaggerated mechanoreflex, at least in males.
Topics: Rats; Male; Animals; Muscle Contraction; Muscle, Skeletal; Capsaicin; Rats, Sprague-Dawley; Reflex; Blood Pressure; Hindlimb
PubMed: 37389947
DOI: 10.1152/ajpheart.00237.2023 -
Journal of Neural Transmission (Vienna,... Jul 2016The lateral part of the mesopontine tegmentum contains functionally important structures involved in the control of posture and gait. Specifically, the mesencephalic... (Review)
Review
The lateral part of the mesopontine tegmentum contains functionally important structures involved in the control of posture and gait. Specifically, the mesencephalic locomotor region, which may consist of the cuneiform nucleus and pedunculopontine tegmental nucleus (PPN), occupies the interest with respect to the pathophysiology of posture-gait disorders. The purpose of this article is to review the mechanisms involved in the control of postural muscle tone and locomotion by the mesopontine tegmentum and the pontomedullary reticulospinal system. To make interpretation and discussion more robust, the above issue is considered largely based on our findings in the experiments using decerebrate cat preparations in addition to the results in animal experimentations and clinical investigations in other laboratories. Our investigations revealed the presence of functional topographical organizations with respect to the regulation of postural muscle tone and locomotion in both the mesopontine tegmentum and the pontomedullary reticulospinal system. These organizations were modified by neurotransmitter systems, particularly the cholinergic PPN projection to the pontine reticular formation. Because efferents from the forebrain structures as well as the cerebellum converge to the mesencephalic and pontomedullary reticular formation, changes in these organizations may be involved in the appropriate regulation of posture-gait synergy depending on the behavioral context. On the other hand, abnormal signals from the higher motor centers may produce dysfunction of the mesencephalic-reticulospinal system. Here we highlight the significance of elucidating the mechanisms of the mesencephalic-reticulospinal control of posture and locomotion so that thorough understanding of the pathophysiological mechanisms of posture-gait disorders can be made.
Topics: Animals; Cats; Decerebrate State; Humans; Locomotion; Midbrain Reticular Formation; Muscle Tonus; Neural Pathways; Pedunculopontine Tegmental Nucleus
PubMed: 26497023
DOI: 10.1007/s00702-015-1475-4