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Patel S, Krishna V, Nicholas J, Welzig CM, Vera C. Preliminary observations on the vasomotor responses to electrical stimulation of the ventrolateral surface of the human medulla. J Neurosurg 2012; 117:150-5. [DOI: 10.3171/2012.3.jns11973] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Pulsatile arterial compression (AC) of the ventrolateral medulla (VLM) is hypothesized to produce the hypertension in a subset of patients with essential hypertension. In animals, a network of subpial neuronal aggregates in the VLM has been shown to control cardiovascular functions. Although histochemically similar, neurons have been identified in the retro-olivary sulcus (ROS) of the human VLM, but their function is unclear.
Methods
The authors recorded cardiovascular responses to electrical stimulation at various locations along the VLM surface, including the ROS, in patients who were undergoing posterior fossa surgery for trigeminal neuralgia. This vasomotor mapping of the medullary surface was performed using a bipolar electrode, with stimulation parameters ranging from 5- to 30-second trains (20–100 Hz), constant current (1.5–5 mA), and 0.1-msec pulse durations. Heart rate (HR) and blood pressure (BP) were recorded continuously from baseline (10 seconds before the stimulus) up to 1 minute poststimulus. In 6 patients, 17 stimulation responses in BP and HR were recorded.
Results
The frequency threshold for any cardiovascular response was 20 Hz; the stimulation intensity threshold ranged from 1.5 to 3 mA. In the first patient, all stimulation responses were significantly different from sham recordings (which consisted of electrodes placed without stimulations). Repeated stimulations in the lower ROS produced similar responses in 3 other patients. Two additional patients had similar responses to single stimulations in the lower ROS. Olive stimulation produced no response (control). Hypotensive and/or bradycardic responses were consistently followed by a reflex hypertensive response. Slight right/left differences were noted. No patient suffered short- or long-term effects from this stimulation.
Conclusions
This stimulation technique for vasomotor mapping of the human VLM was safe and reproducible. Neuronal aggregates near the surface of the human ROS may be important in cardiovascular regulation. This method of vasomotor mapping with measures of responses in sympathetic tone (microneurography) should yield additional data for understanding the neuronal network that controls cardiovascular functions in the human VLM. Further studies in which a concentric bipolar electrode is used to generate this type of vasomotor map should also increase understanding of the pathophysiological mechanisms of neurogenically mediated hypertension, and assist in the design of studies to prove the hypothesis that it is caused by pulsatile AC of the VLM.
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Affiliation(s)
- Sunil Patel
- 1Division of Neurosurgery, Department of Neuroscience; and
| | - Vibhor Krishna
- 1Division of Neurosurgery, Department of Neuroscience; and
| | - Joyce Nicholas
- 1Division of Neurosurgery, Department of Neuroscience; and
- 2Division of Biostatistics and Epidemiology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | | | - Cristian Vera
- 1Division of Neurosurgery, Department of Neuroscience; and
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Saberi H, Meybodi AT, Zeinalizadeh M. Normalization of systemic arterial hypertension following removal of posterior fossa hemangioblastoma: a case report. CASES JOURNAL 2009. [PMID: 20181189 PMCID: PMC2827080 DOI: 10.1186/1757-1626-2-7106] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The concept of compression of the rostral ventrolateral medulla as a cause for hypertension is gaining more and more interest. This report is about a 36-year-old male with a three years history of hypertension who presented with a posterior fossa mass suggestive of a hemangioblastoma. Laboratory and imaging studies ruled out the presence of von Hippel-Lindau disease and/or concomitant pheochromocytoma. Post-surgical blood pressure monitoring revealed a 40 mmHg decline in blood pressure. It could be hypothesized that alleviation the compressive effect of the tumour on the rostral ventrolateral medulla as proposed by previous studies could be a contributing factor.
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Saberi H, Meybodi AT, Zeinalizadeh M. Normalization of systemic arterial hypertension following removal of posterior fossa hemangioblastoma: a case report. CASES JOURNAL 2009; 2:7106. [PMID: 20181189 PMCID: PMC2827080 DOI: 10.1186/1757-1626-0002-0000007106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Accepted: 02/19/2009] [Indexed: 05/28/2023]
Abstract
The concept of compression of the rostral ventrolateral medulla as a cause for hypertension is gaining more and more interest. This report is about a 36-year-old male with a three years history of hypertension who presented with a posterior fossa mass suggestive of a hemangioblastoma. Laboratory and imaging studies ruled out the presence of von Hippel-Lindau disease and/or concomitant pheochromocytoma. Post-surgical blood pressure monitoring revealed a 40 mmHg decline in blood pressure. It could be hypothesized that alleviation the compressive effect of the tumour on the rostral ventrolateral medulla as proposed by previous studies could be a contributing factor.
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Affiliation(s)
- Hooshang Saberi
- Departement of Neurosurgery, Brain and Spinal Injuries Repair Research Center (BASIR), Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, 14197, Iran
| | - Ali Tayebi Meybodi
- Departement of Neurosurgery, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, 14197, Iran
| | - Mehdi Zeinalizadeh
- Departement of Neurosurgery, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, 14197, Iran
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4
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Kan P, Couldwell WT. Posterior fossa brain tumors and arterial hypertension. Neurosurg Rev 2006; 29:265-9; discussion 269. [PMID: 16924459 DOI: 10.1007/s10143-006-0036-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Revised: 03/16/2006] [Accepted: 04/30/2006] [Indexed: 11/29/2022]
Abstract
Hypertension caused by arterial compression of the rostral ventrolateral medulla is well described. Much less information is available on the association between neurogenic hypertension and posterior fossa brain tumors. To date, multiple reports have supported the impression that a small subpopulation of patients with posterior fossa tumors can present with arterial hypertension, and many of those patients achieved significant improvement of their hypertension after tumor resection and medullary decompression. To review the relationship between posterior fossa brain tumors and hypertension, we detail the history, basic science, and clinical reports along with an illustrative case regarding this topic.
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Affiliation(s)
- Peter Kan
- Department of Neurosurgery, University of Utah School of Medicine, 30 North 1900 East, Suite 3B409, Salt Lake City, 84132, USA
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5
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Coffee RE, Nicholas JS, Egan BM, Rumboldt Z, D'Agostino S, Patel SJ. Arterial compression of the retro-olivary sulcus of the medulla in essential hypertension: a multivariate analysis. J Hypertens 2005; 23:2027-31. [PMID: 16208145 DOI: 10.1097/01.hjh.0000187256.02072.41] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Pulsatile arterial compression (AC) of the ventrolateral medulla (VLM) has been postulated to cause neurogenically mediated essential hypertension (EHTN). We aimed to establish whether the association between AC of specifically the retro-olivary sulcus (ROS) of the VLM and EHTN was significant, while controlling for other risks associated with EHTN. DESIGN Case-control study. METHODS Posterior fossa magnetic resonance imaging scans of 131 subjects, including 58 subjects with EHTN and 73 normotensives, were reviewed to determine the presence of AC in the ROS. The history of other risk factors for EHTN was obtained by reviewing medical records. RESULTS Multivariate logistic regression analysis of these data shows a significant association between AC in the ROS (right and/or left) and EHTN [odds ratio (OR) = 3.03, 95% confidence interval (CI) = 1.30, 7.06]. This analysis was done controlling for other known EHTN risk factors such as age, race, sex, diabetes, and obesity. A secondary analysis also controlling for these variables shows that AC of both the right and left ROS are independently associated with EHTN (right AC: OR = 5.04, 95% CI = 1.33, 19.17; left AC: OR = 3.39, 95% CI = 1.20, 9.60). CONCLUSIONS In this retrospective study of subjects with EHTN and normotensive controls that had undergone magnetic resonance imaging of the posterior fossa, AC of the ROS on either side of the medulla is a significant independent risk factor in EHTN. Further studies are required to determine whether this is true for the general population of patients with neurogenically mediated EHTN.
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Affiliation(s)
- Robert E Coffee
- College of Medicine, Medical University of South Carolina, Charleston, 29425, USA
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Nicholas JS, D'Agostino SJ, Patel SJ. Arterial Compression of the Retro-Olivary Sulcus of the Ventrolateral Medulla in Essential Hypertension and Diabetes. Hypertension 2005; 46:982-5. [PMID: 16087783 DOI: 10.1161/01.hyp.0000174617.09146.d4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Pulsatile arterial compression in the retro-olivary sulcus along the surface of the ventrolateral medulla has been postulated as a mechanism in both essential hypertension and diabetes. The objective of this study was to test the independent effect of arterial compression in the retro-olivary sulcus on each of these diseases, using separate logistic regression models to control for other known risk factors. Study design was case–control. The study population consisted of 147 consecutive patients treated for neurological conditions requiring MRI of the posterior cranial fossa. Information on essential hypertension, diabetes, and risk factors for each disease was abstracted from medical records. Presence of arterial compression was determined by blinded review of magnetic resonance images. In the essential hypertension analysis, odds of arterial compression among hypertensive patients were 2.99-times the odds among normotensive subjects (
P
=0.04), controlling for hypertension risk factors such as age, body mass index, race, diabetes, and family history of hypertension. Of compressed hypertensive subjects, 56% were compressed on the left and 44% were compressed on the right. In the diabetes analysis, odds of arterial compression among diabetic subjects were 1.14-times the odds among nondiabetic subjects (
P
=0.83). Of compressed diabetic subjects, 60% were compressed on the left, and 40% were compressed on the right. Results suggest that arterial compression of the retro-olivary sulcus may be an independent risk factor for essential hypertension in this population, supporting the postulate for a treatable (with microvascular decompression) neural mechanism for essential hypertension. However, in the diabetic population, the slight increase in the odds of arterial compression was not significant.
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Affiliation(s)
- Joyce S Nicholas
- Division of Neurosurgery, Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, USA.
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Mueller PJ, Buckwalter JB, Clifford PS. Tracheal tone and the role of ionotropic glutamate receptors in the nucleus ambiguus. Brain Res 2004; 1021:54-62. [PMID: 15328031 DOI: 10.1016/j.brainres.2004.06.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2004] [Indexed: 10/26/2022]
Abstract
Excitatory amino acid (EAA) transmission in the rostral portion of the ventrolateral medulla (RVLM) appears to be required for reflex airway constriction. The purpose of the present study was to determine whether our prior observations of right sided dominance are also reflected at the level of the RVLM, particularly at the right nucleus ambiguus (NA). Microinjection of glutamate (109 nl, 100 mM) into the right NA of anesthetized dogs produced significant increases in tracheal smooth muscle tone as assessed by pressure changes in a saline filled cuff of the endotracheal tube (Delta15 +/- 2 mm Hg). Increasing inspired CO2 increased tracheal cuff pressure (Delta33 +/- 2 mm Hg) which was abolished by microinjections of the EAA antagonist kynurenic acid (109 nl, 100 mM) or the non-NMDA antagonist 6-nitro-7-sulfamobenzoquinoxaline-2,3-dione (NBQX, 109 nl, 10 mM) into the right NA. These results confirm that EAA receptors in the right NA are capable of modulating tracheal tone and suggest that non-NMDA receptors in the right NA are required for reflex airway constriction produced by systemic hypercapnia. Furthermore, the effects of right-sided NA microinjections in the present study, although not completely definitive, are consistent with previous studies that suggest dominant control of canine tracheal tone by the right vagus.
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Affiliation(s)
- Patrick J Mueller
- Department of Anesthesiology, Medical College of Wisconsin and Veterans Affairs Medical Center, Milwaukee, WI 53295, USA.
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Xu Z, Shi L, Yao J. Central angiotensin II-induced pressor responses and neural activity in utero and hypothalamic angiotensin receptors in preterm ovine fetus. Am J Physiol Heart Circ Physiol 2003; 286:H1507-14. [PMID: 14684369 DOI: 10.1152/ajpheart.00764.2003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The central renin-angiotensin system is important in the control of blood pressure in the adult. However, few data exist about the in utero development of central angiotensin-mediated pressor responses. Our recent studies have shown that the application of ANG II into the fetal brain can increase blood pressure at near term. The present study determined fetal blood pressure and heart rate in response to a central application of ANG II in the chronically prepared preterm ovine fetus, determined the action sites marked by c-Fos expression in the fetal central pathways after intracerebroventricular injection of ANG II in utero, and determined angiotensin subtype 1 receptors in the fetal hypothalamus. Central injection of ANG II significantly increased fetal mean arterial pressure (MAP). Adjusted fetal MAP against amniotic pressure was also increased by ANG II. Fetal heart rate was subsequently decreased after the central administration of ANG II and/or the increase of blood pressure. ANG II induced c-Fos expression in the central putative cardiovascular area, the paraventricular nuclei in the brain sympathetic pathway. Application of ANG II also caused intense Fos immunoreactivity in the tractus solitarius nuclei in the hindbrain. In addition, intense angiotensin subtype 1 receptors were expressed in the hypothalamus at preterm. These data demonstrate that central ANG II-related pressor centers start to function as early as at preterm and suggest that the central angiotensin-related sympathetic pathway is likely intact in the control of blood pressure in utero.
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Affiliation(s)
- Zhice Xu
- Harbor-University of California Los Angeles Medical Center, (UCLA), Harbor-UCLA Medical Center, Torrance, CA 90502, USA.
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9
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Lohmeier TE, Warren S, Cunningham JT. Sustained activation of the central baroreceptor pathway in obesity hypertension. Hypertension 2003; 42:96-102. [PMID: 12771049 DOI: 10.1161/01.hyp.0000076092.10923.fd] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The major goal of this study was to determine whether there is increased activation of medullary neurons that participate in the central baroreceptor reflex pathway in dogs with obesity-induced hypertension, a model of hypertension that is associated with increased sympathetic activity. We used Fos-like (Fos-Li) protein immunohistochemical methods to determine activation of neurons in the nucleus tractus solitarius (NTS), caudal ventrolateral medulla (CVLM), and rostral ventrolateral medulla (RVLM). Dogs were fed either a regular diet or an identical diet with the addition of 0.5 to 0.9 kg of cooked beef fat. After approximately 6 weeks of the high fat diet, body weight (36.3+/-0.4 vs 21.5+/-0.5 kg), mean arterial pressure (105+/-4 vs 91+/-3 mm Hg), and heart rate (97+/-4 vs 70+/-3 bpm) were significantly greater in obese than in control dogs, respectively. There was little Fos-Li immunoreactivity in medullary neurons of control dogs but marked reactivity in obese dogs. Specifically, the number of Fos-Li-positive cells in the NTS and CVLM was 3 to 5 times greater in obese than in control dogs. Furthermore, despite sustained activation of these baroreceptor-sensitive neurons, there was a significantly greater number of Fos-Li positive cells in the RVLM of dogs fed the high fat diet. As baroreceptor suppression of sympathoexcitatory cells in the RVLM is mediated by activation of neurons in the NTS and CVLM, these results support recent findings indicating that baroreflex suppression of sympathetic activity is a long-term compensatory response in hypertension. However, sympathoexcitatory inputs onto RVLM neurons would appear to predominate over the inhibitory effects of the baroreflex in obesity hypertension.
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Affiliation(s)
- Thomas E Lohmeier
- Department of Physiology, University of Mississippi Medical Center, 2500 North State St, Jackson, Miss 39216-4505, USA.
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10
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Lohmeier TE, Lohmeier JR, Warren S, May PJ, Cunningham JT. Sustained activation of the central baroreceptor pathway in angiotensin hypertension. Hypertension 2002; 39:550-6. [PMID: 11882606 DOI: 10.1161/hy0202.103003] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recent studies indicate that renal sympathetic nerve activity is chronically suppressed in angiotensin (Ang II) hypertension and that baroreflexes play a critical role in mediating this response. To support these findings, we determined whether the hypertension associated with chronic infusion of Ang II at 4.8 pmol/kg per minute (5ng/kg per minute) produces sustained activation of medullary neurons that participate in the central baroreceptor reflex pathway. We used Fos-like (Fos-Li) protein immunohistochemical methods to determine activation of neurons in the nucleus tractus solitarius (NTS), caudal ventrolateral medulla (CVLM), and rostral ventrolateral medulla (RVLM). Results were compared in three groups of chronically instrumented dogs subjected to infusion of: 1) saline (control); 2) Ang II-2 hours (acute); and 3) Ang II-5 days (chronic). Mean arterial pressure increased 22 +/- 3 and 35 +/- 3 mm Hg during acute and chronic Ang II infusion, respectively. There was little Fos-Li immunoreactivity in medullary neurons in control dogs. In contrast, during acute Ang II infusion there was a 2- to 3-fold increase in Fos-Li staining in the NTS and CVLM, but no increase in staining in RVLM neurons. As baroreceptor suppression of sympathoexcitatory cells in the RVLM is mediated by activation of neurons in the NTS and CVLM, these results were expected. More importantly, this same pattern of central neuronal activation was observed during chronic Ang II hypertension. Therefore, these results support recent findings indicating that baroreflex suppression of renal sympathetic nerve activity is a long-term compensatory response in Ang II hypertension.
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Affiliation(s)
- Thomas E Lohmeier
- Department of Physiology, University of Mississippi Medical Center, Jackson 39216-4505, USA.
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11
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Forster HV, Pan LG, Lowry TF, Feroah T, Gershan WM, Whaley AA, Forster MM, Sprtel B. Breathing of awake goats during prolonged dysfunction of caudal M ventrolateral medullary neurons. J Appl Physiol (1985) 1998; 84:129-40. [PMID: 9451627 DOI: 10.1152/jappl.1998.84.1.129] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cooling the caudal M ventrolateral medullary (VLM) surface for 30 s results in a sustained apnea in anesthetized goats but only a 30% decrease in breathing in awake goats. The purpose of the present study was to determine, in the awake state, the effect of prolonged (minutes, hours) caudal M neuronal dysfunction on eupneic breathing and CO2 sensitivity. Dysfunction was created by ejecting excitatory amino acid receptor antagonists or a neurotoxin on the VLM surface through guide tubes chronically implanted bilaterally on a 10- to 12-mm2 portion of the caudal M VLM surface of 12 goats. Unilateral and bilateral ejections (1 microliter) of selective antagonists for N-methyl-D-aspartic acid or non-N-methyl-D-aspartic acid receptors had no significant effect on eupneic breathing or CO2 sensitivity. Unilateral ejection of a nonselective excitatory amino acid receptor antagonist generally had no effect on eupneic breathing or CO2 sensitivity. However, bilateral ejection of this antagonist resulted in a significant 2-Torr hypoventilation during eupnea and a significant reduction in CO2 sensitivity to 60 +/- 9% of control. Unilateral ejection of the neurotoxin kainic acid initially stimulated breathing; however, breathing then returned to near control with no incidence of apnea. After the kainic acid ejection, CO2 sensitivity was reduced significantly to 60 +/- 7% of control. We conclude that in the awake state a prolonged dysfunction of caudal M VLM neurons results in compensation by other mechanisms (e.g., carotid chemoreceptors, wakefulness) to maintain near-normal eupneic breathing, but compensation is more limited for maintaining CO2 sensitivity.
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Affiliation(s)
- H V Forster
- Department of Physiology, Medical College of Wisconsin, Milwaukee, USA
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12
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Dickinson LD, Papadopoulos SM, Hoff JT. Neurogenic hypertension related to basilar impression. Case report. J Neurosurg 1993; 79:924-8. [PMID: 8246061 DOI: 10.3171/jns.1993.79.6.0924] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The authors report the resolution of essential hypertension following transoral odontoidectomy and medullary decompression in a 39-year-old woman with basilar invagination. Current understanding of central regulation of the cardiovascular system is discussed and the pertinent neuroanatomy illustrated. Experimental and clinical evidence supporting the role of neurogenic mechanisms in the pathogenesis of hypertension is reviewed.
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Affiliation(s)
- L D Dickinson
- Department of Surgery, University of Michigan, Ann Arbor
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13
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Poree LR, Schramm LP. Interaction between medullary and cervical regulation of renal sympathetic activity. Brain Res 1992; 599:297-301. [PMID: 1363286 DOI: 10.1016/0006-8993(92)90404-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We have reported that electrical or glutamate stimulation of the dorsolateral surface of the cervical spinal cord elicits a 40-60% decrease in renal sympathetic activity (RSA) in anesthetized rats. Because evoked sympatho-inhibition was observed, however, only after transection of the cervical spinal cord at C1, we suggested that unidentified supraspinal neurons affect the regulation of RSA by cervical neurons. In the present experiments, we tested the hypothesis that the modulatory supraspinal neurons are located in the ventrolateral medulla by observing the effects of rostroventral, lateral, medullary (RVLM) injections of the GABAergic agonist, muscimol, on baseline RSA and on our ability to inhibit that activity by cervical stimulation. GABAergic inhibition in the RVLM of chlorolose anesthetized rats elicited changes in RSA that were similar to those observed after transection of the spinal cord, including a 41% decrease in mean arterial pressure and a 44% increase in RSA. Moreover, after muscimol inhibition of RVLM neurons, electrical or glutamate stimulation of the dorsolateral cervical spinal cord elicited a decrease in RSA in otherwise intact rats. These results suggest that neurons in the RVLM interact with neurons in the cervical spinal cord in the regulation of RSA.
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Affiliation(s)
- L R Poree
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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