Release of antidiuretic hormone during mass-induced elevation of intracranial pressure

Hyponatremia and Encephalopathy in a 55-Year-old Woman with Syndrome of Inappropriate Antidiuretic Hormone Secretion as an Isolated Presentation of SARS-CoV-2 Infection

BACKGROUND During the coronavirus disease 2019 (COVID-19) pandemic of 2020, varied presentations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been reported. The present report is of a case of hyponatremia and encephalopathy due to the syndrome of inappropriate antidiuretic hormone secretion (SIADH) as the main presentation of SARS-CoV-2 infection in a 55-year-old woman. CASE REPORT A 55-year-old woman with type II diabetes mellitus presented with confusion and slurring of speech, with a temperature of 38.5°C, heart rate of 120 bpm, blood pressure of 159/81 mmHg, and oxygen saturation of 98% on room air. She did not have edema on examination. Laboratory testing showed a low sodium level of 116 mEq/L (reference range, 135-145 mEq/L) with urine osmolarity of 364 mOsm/kg, urinary sodium of 69 mEq/L, urinary potassium of 15.6 mEq/L, and serum osmolarity of 251 mOsm/kg. The patient had normal serum thyroid-stimulating hormone and cortisol levels. A chest X-ray should no pulmonary infiltrates nor did a lumbar puncture reveal signs of infection. A real-time SARS-CoV-2 polymerase chain reaction assay was positive for COVID-19. Brain imaging with computed tomography was negative for acute infarct, intracranial hemorrhage, and mass effect. Based on findings from laboratory testing and physical examination, a diagnosis of SIADH was made. The patient was treated with 3% hypertonic saline, followed by salt tablets and fluid restriction, with improvement in her clinical symptoms and serum sodium level. CONCLUSIONS The present report is of a rare but previously reported association with SARS-CoV-2 infection. Encephalopathy and hyponatremia associated with SIADH without pneumonia or other symptoms of infection should be an indication for testing for SARS-CoV-2 infection.

Antidiuretic hormone release associated with increased intracranial pressure independent of plasma osmolality

OBJECTIVE

Introduce and evaluate a new model which explains the release of brain antidiuretic hormone (ADH) independent of plasma osmolality.

METHODS

Systematic review and critical analysis of the professional literature.

RESULTS

Primary electronic database searches using key terms revealed 57,432 hits. Secondary searches with application of specific inclusion and exclusion criteria and manual inspection for completeness reduced the total number of studies to fourteen (N = 14). Twelve (N = 12) studies investigated human subjects in the hospital settings, and two (N = 2) studies investigated animals (rhesus monkeys and dog) under invasive experimental conditions. All fourteen studies included direct or indirect indicators of intracranial pressure (ICP), measurements of plasma ADH, and plasma osmolality or urine osmolality. Findings, in brief, reveal a stable and positive association between increased intracranial pressure (ICP) and increased ADH release, in patients with low or normal blood osmolality. Findings are reliable and reproducible across human and animal populations.

CONCLUSIONS

Findings support the proposed model, which explains increase secretion of brain ADH when plasma osmolality is low or within normal limits. Mechanical pressures exerted on hypothalamic nuclei, especially paraventricular and supra-optic nuclei, as a consequence of increased intracranial pressure, produce release of ADH, independent of plasma osmolality. The mechanical pressure model explains release of ADH previously unexplained by traditional plasma osmolality models. Findings have important clinical implications for the medical and surgical management of patients.

Postoperative hyponatremia following calvarial vault remodeling in craniosynostosis

BACKGROUND

  The incidence, severity, and risk factors for the development of hyponatremia in patients undergoing craniosynostosis surgery are not well known.

OBJECTIVE

  To determine the incidence and severity of hyponatremia as a complication in surgical correction of craniosynostosis and to identify risk factors for postoperative hyponatremia.

METHODS

  A retrospective medical record review for 2003-2008 of the Cleft and Craniofacial Database was made. Specific data collected included sodium values, age, weight, type of surgery, duration of surgery, administration of DDAVP, composition and volume of pre-operative, intra-operative, postoperative parenteral fluids, volume of blood, colloid, and crystalloid transfused, estimated blood loss (EBL), medications, comorbidities, pre-operative signs of elevated intracranial pressure (ICP), syndromic vs nonsyndromic craniosynostosis, and the complications associated with hyponatremia.

RESULTS

  A total of 72 records were reviewed. The incidence of postoperative hyponatremia was 30.6%. There was no intra-operative hyponatremia. While hospital stay was not prolonged, ICU stay was significantly longer (1.9 vs 2.9 days, P = 0.001). Elevated ICP was significantly associated with hyponatremia (P < 0.002). A greater volume of blood loss (EBL) was associated with postoperative hyponatremia (P = 0.019). Patients with normal pre-operative ICP were more likely to become hyponatremic if they were female (relative risk = 2.43; P < 0.05). The average decrease in sodium was greater in patients receiving hyponatremic (hypotonic) vs normonatremic (isotonic) postoperative IVF's (5.5 vs 3.2 mEq·l(-1), P = 0.039). There were no postoperative complications related to hyponatremia.

CONCLUSIONS

  The incidence of postoperative hyponatremia after calvarial vault remodeling was determined to be 30.6%. Hyponatremia was significantly associated with increased pre-operative ICP, blood loss, and female gender (normal pre-operative ICP). The average decrease in sodium was greater in patients receiving hyponatremic postoperative IVF's.

Predictors of AVP and TSH levels and the timing of first voiding in the newborn

To evaluate obstetric predictors of umbilical cord plasma AVP levels, serum TSH levels and the timing of first voiding, 87 singleton term newborns were divided into three groups: group A, vaginal delivery (n = 30); group B, cesarean section (CS) during labor (n = 26); and group C, elective CS (n = 31). The AVP concentration was 120 (0.7-2170) ng/L in group A, 1.8 (0.01-183) ng/L in group B, and 0.8 (0.01-30) ng/L in group C (p < 0.001). In group A, the TSH concentration was 10.20 (3.5-30.80) mU/L; in group B, 5.40 (2.10-43.00) mU/L; and in group C, 5.30 (2.90-11.00) mU/L (p = 0.001). Duration of labor had a positive correlation with AVP (p < 0.001) and TSH (p = 0.001) concentrations. The timing of first voiding had a positive correlation with gestational age (p = 0.003), volume of additional feeding before first voiding (p < 0.001), and umbilical AVP concentration (p = 0.023). The AVP and TSH concentrations are associated with mode of delivery and duration of labor and AVP levels also with the timing of first voiding in the newborn.

Inappropriate secretion of antidiuretic hormone in a patient with chronic inflammatory demyelinating polyneuropathy

A 54-year-old man suffered from a relapse of chronic inflammatory demyelinating polyneuropathy (CIDP), and developed quadriplegia and somnolence requiring mechanical ventilation for respiratory failure. Serum Na concentration remained at low levels during the clinical course, and a diagnosis of inappropriate secretion of antidiuretic hormone (SIADH) was made. The present case had not only acute aggravation of CIDP with autonomic dysfunction but also intracranial hypertension caused by increased CSF protein (maximum level, 1,315 mg/dl). It seemed likely that injury of the afferent fibers of the baroregulatory pathway or intracranial hypertension might have contributed to SIADH in this patient.

Cerebral oedema after subarachnoid haemorrhage. Pathogenetic significance of vasopressin

The authors report the frequency, characteristic clinical symptoms, laboratory alterations and diagnostic criteria of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) after subarachnoid haemorrhage. The data on 290 patients with subarachnoid haemorrhage (SAH) during a period of years at the Division of Neurosurgery, University Medical School, Szeged, are analysed. Twenty-seven (9.3%) patients developed SIADH. Thirteen (4.5%) patients had severe and 14 (4.8%) had mild SIADH. The problems of the treatment are discussed in detail and the different therapeutic methods are listed: NaCl infusion, water withdrawal and administration of Dilantin, diuretics, mineralocorticosteroids, lithium and demeclocycline. The undesirable side-effects observed accompanying various therapeutic regimen are analysed. The introduction of V2 antagonists into clinical practice appears to be a most perspective procedure. For study of the pathogenesis of SIADH following SAH, the possibility of treatment with V2 antagonists on an experimental model of SAH in rat was created. A significant water retention and increases in brain water and sodium content were observed in rats with SAH. Plasma AVP levels were also elevated after SAH. AVP plays an important role in the development of antidiuresis following water loading and disturbance of the brain water and electrolyte balance after SAH. Water retention and the higher brain water and sodium accumulation could be totally prevented by administration of a V2 antagonist. These results demonstrate that cerebral oedema generated by artificial cerebral bleeding in rats is significantly reduced following the administration of a highly specific V2 antagonist, suggesting a new approach to the treatment of SIADH.

Posttraumatic hyperthermia: a possible result of fronto-diencephalic dysfunction

A patient with traumatic bifrontal hemorrhagic lesions developed hyperthermia associated with autonomic dysfunction shortly after admission. This case illustrates that posttraumatic hyperthermia may also occur at a markedly less disturbed baseline neurological level, possibly secondary to disruption of fronto-diencephalic pathways.

Dissociation between activation of the hypothalamo-hypophyseal antidiuretic system and the type of diuresis during acute intracranial hypertension. Experimental observation

Acute cerebral compression by a supra- and infratentorial balloon produced a triphasic pattern of diuresis. The 1st phase was characterized by polyuria associated with five fold increase of plasma (p) antidiuretic hormone (ADH) concentration, decreased urine osmolality in spite of natriuresis and blood pressure elevation. The 2nd phase was characterized by oliguria, a decrease of pADH and reduced urine Na+ concentration, whereas urine osmolality transiently increased. At this stage there was respiratory arrest and fall of blood pressure. The final stage was diabetes insipidus (DI), when EEG activity had disappeared. An increase of serum osmolality mainly occurred during the last DI phase. Serum Na+ concentration fluctuated slightly during the whole period of diuresis. These results present evidence, that the diuresis pattern reflects the hypothalamo-hypophyseal antidiuretic system (HHAS) reaction to acute intracranial pressure (ICP) increase with the vegetative symptoms of cerebral shock.

Humoral regulation of blood flow to choroid plexus: role of arginine vasopressin

The goal of this study was to examine humoral mechanisms that regulate blood flow to the choroid plexus. We determined the effects of arginine vasopressin on blood flow (microspheres) to the choroid plexus in anesthetized and awake rabbits. In anesthetized rabbits, blood flow to the choroid plexus was 342 +/- 31 (mean +/- SEM) ml/min/100 g under control conditions. Intravenous infusion of vasopressin at 4 and 40 mU/kg increased plasma vasopressin levels from 11 +/- 1 to 55 +/- 15 and 441 +/- 120 pg/ml, respectively, and blood flow to the choroid plexus decreased by 48 +/- 6% and 70 +/- 4%. Cerebral blood flow was not affected by infusion of vasopressin. Similar responses to infusion of vasopressin were observed in awake rabbits. The V1 antagonist [d(CH2)5Tyr(Me)AVP] (10 micrograms/kg i.v.) had no effect on resting blood flow, but abolished the effect of vasopressin on blood flow to the choroid plexus. Vasoconstrictor responses of the choroid plexus to intravenous infusion of phenylephrine were not attenuated by the V1 antagonist. Thus, circulating vasopressin, at plasma levels that are observed under physiological and pathophysiological conditions, has marked effects on blood flow to the choroid plexus. These effects appear to be mediated through a V1 receptor. We speculate that vasopressin may play an important role in regulation of blood flow to the choroid plexus and perhaps in the regulation of cerebrospinal fluid production.

Cerebral herniation in patients receiving cisplatin

5 Patients with intracranial mass lesions are described who experienced cerebral herniation and coma following intravenous cisplatin therapy. Although the pathogenesis of the acute cerebral swelling is unknown, it is most likely multifactorial. Possible contributing factors include pre-existing cerebral edema, acute hypo-osmolality with fluid shifts into an already swollen brain, seizures and possible direct neurotoxicity of cisplatin.

Hyponatremia hypo-osmolarity in neurosurgical patients. "Appropriate secretion of ADH" and "cerebral salt wasting syndrome"

This prospective study is based on 256 patients with severe brain injury. Six patients (2.3%) developed the clinical picture of inappropriate secretion of antidiuretic hormone (SIADH): 3 in the first 3 days following the injury, 3 after more than a week. Their ADH plasmatic level were measured by radio-immunoassay. In the former, many factors, largely iatrogenic, can explain the increased secretion of ADH we found and which is then definitely "appropriate". It should be prevented by fluid restriction. In the latter, we found adequately low ADH levels, when the hypo-osmolarity is taken into account. Here, the aetiology seems to be a renal salt loss, eventually in relation to a natriuric factor (e.g. atrial natriuretic factor), justifying the term: "Cerebral salt wasting syndrome". With the resistance to fluid restriction, the treatment still remains a problem.

Studies of vasopressin in the human cerebrospinal fluid

The development of sensitive radioimmunoassays has permitted measurement of the low concentration of vasopressin in the human cerebrospinal fluid. There is accumulating evidence to suggest that vasopressin is involved in a variety of brain functions. As an effective blood-cerebrospinal fluid barrier to vasopressin has been demonstrated, the concentration of vasopressin in the cerebrospinal fluid probably reflects the release of vasopressin within the brain. In human subjects without intracranial disease, the concentration of vasopressin in the cerebrospinal fluid is in the range 0.5-2.0 pg/ml with only little diurnal variation. Intracranial disorders associated with increased intracranial pressure may cause increased cerebrospinal fluid vasopressin concentrations, whereas degenerative brain diseases are associated with low concentrations. Only little is known about the physiologic stimuli which alter the concentration of vasopressin in cerebrospinal fluid. The concentration in cerebrospinal fluid is not influenced by a number of stimuli that cause release of vasopressin into the blood, i.e. changes in plasma osmolality, postural changes, and nausea. Elevation of the intracranial pressure, changes in the composition of the cerebrospinal fluid, electrical stimulation of the hypothalamus, and severe hemorrhage provoke an increase in cerebrospinal fluid vasopressin level.

Early syndrome of inappropriate secretion of antidiuretic hormone in a child with burn injury

A 17-month-old boy presented with 10% to 12% first- and second-degree burns secondary to scald injury. He rapidly developed hyponatremia secondary to inappropriate antidiuretic hormone secretion, manifested by the occurrence of seizures. After appropriate therapy was instituted, the child had an uneventful recovery. To the best of the authors' knowledge, this problem has not been reported previously in a child with a relatively mild burn.

Cerebrospinal fluid and plasma vasopressin during short-time induced intracranial hypertension

The response of plasma and ventricular cerebrospinal fluid vasopressin concentration to short-time induced intracranial hypertension was studied in 8 patients with hydrocephalus, defined as ventricular enlargement on computerized tomography. In connection with measurement of conductance to cerebrospinal fluid outflow, the concentration of vasopressin in plasma and cerebrospinal fluid was measured during perfusion at a low (less than 10 mmHg) and at a high (greater than 20 mmHg) intraventricular pressure level. Mean plasma vasopressin concentration was increased from 2.4 +/- 0.4 pg/ml (SEM) during perfusion at the low pressure level to 4.2 +/- 0.8 pg/ml (p less than 0.01) at the high pressure level. The cerebrospinal fluid concentrations of vasopressin at the low and high intraventricular pressure were 1.2 +/- 0.1 pg/ml and 1.7 +/- 0.2 pg/ml (p less than 0.05), respectively. However, only half of the patients responded to the increase in intraventricular pressure with an increase in cerebrospinal fluid vasopressin concentration exceeding 50%. The results of the present study suggest that an increase in the intracranial pressure might be a stimulus for vasopressin release in both the blood and the cerebrospinal fluid.

Diuresis and urine concentration during CPAP in newborn infants

The impact of continuous positive airways pressure (CPAP) on diuresis and urine concentration was studied in newborn preterm infants with respiratory insufficiency with and without pulmonary X-ray changes. Urine output and osmolality, sodium balance and blood pressure were measured before, during and after CPAP application. In all infants urine osmolality rose and urine output decreased significantly when high CPAP (8 cm H2O) was applied, especially in infants without radiographic pulmonary changes. Three infants also developed hyponatremia at high CPAP levels. The results indicate that high CPAP levels per se may affect fluid balance inadvertently. Therefore fluid intake and urine output should be monitored closely during CPAP treatment.

Elevation of plasma concentrations of arginine vasopressin following perinatal asphyxia

Hypoxic ischemic encephalopathy is a major cause of mortality in neonates. Studies in experimental subjects have shown differing responses of plasma arginine vasopressin to hypoxia. Plasma arginine vasopressin levels, serum osmolality, urine osmolality and fluid intakes were measured in thirteen asphyxiated and nineteen control newborn infants during the first seventy-two hours of life. In the asphyxiated infants plasma arginine vasopressin was found to be elevated as compared to control infants on days one (p less than 0.001) and two (p less than 0.007) but not on day three of life. Urine osmolality was also elevated in the study patients on days one (p less than 0.01) and two (p less than 0.001) but not on day three, in spite of equal intakes of fluid on day one in both groups and significantly diminished fluid intake on days two and three in the study patients. Serum osmolality was not different between the two groups on any day studied, and was felt to be on the basis of diminished intake in the study infants. The data presented in this study support the concept that arginine vasopressin release occurs following perinatal asphyxia in term newborn infants.

Vasopressin in fetal cerebrospinal fluid

Vasopressin concentrations were measured in the cerebrospinal fluid in two hydrocephalic fetuses at 33 and 34 weeks of gestation. The vasopressin concentrations in cerebrospinal fluid were 0.8 and 0.6 pg/ml, and in amniotic fluid 0.4 and 1.0 pg/ml, respectively. Previously measured vasopressin concentrations in amniotic fluid of the normal fetuses have been of the same magnitude.

Hyponatraemia in the first week of life in preterm infants. Part I. Arginine vasopressin secretion

Continuous sequential urinary arginine vasopressin measurements in 14 preterm, ventilated infants suggest that both osmoreceptor and volume receptor systems are able to stimulate the prolonged secretion of arginine vasopressin from 26 weeks' gestation. The kidney is able to respond to arginine vasopressin stimulation from the first day of life and from 26 weeks' gestation. A maximum urine osmolality not exceeding 550 mOsm/kg was reached which varied with hydration of the infant. Excretion of arginine vasopressin and urine osmolality increased during deterioration of respiratory illness, mask ventilation, bilateral pneumothoraces, and severe intraventricular haemorrhage. The data show that inappropriate arginine vasopressin secretion is common during illness in the first week of life in preterm infants and that strict attention must be paid to water balance during this time.

Cerebrospinal fluid vasopressin and increased intracranial pressure

Cerebrospinal fluid and plasma vasopressin were measured in patients with cerebral disorders associated with varying levels of elevated intracranial pressure. The mean cerebrospinal fluid vasopressin concentration was significantly increased in patients with pseudotumor cerebri (2.0 +/- 0.2 [SEM] pg/ml), intracranial tumor (2.3 +/- 0.4 pg/ml), and intracranial hemorrhage (1.9 +/- 0.3 pg/ml) compared with control patients (1.2 +/- 0.1 pg/ml). A significant relationship was found between intracranial pressure and the cerebrospinal fluid vasopressin concentration within all groups of patients and in the whole sample as well (r = 0.79; p less than 0.001). In the groups of patients with intracranial tumor, hydrocephalus, and intracranial hemorrhage, some individuals showed plasma vasopressin concentrations inappropriate to the corresponding plasma osmolality, but no relationship was found between intracranial pressure and plasma vasopressin concentration. It is suggested that increased intracranial pressure is a stimulus to centrally released vasopressin. The clinical importance of increased cerebrospinal fluid vasopressin concentrations is still not known.

Hyponatremia and natriuresis following subarachnoid hemorrhage in a monkey model

A monkey model of subarachnoid hemorrhage (SAH) was used to study both the incidence of hyponatremia and natriuresis and the associated changes in antidiuretic hormone (ADH) secretion and salt and water balance. Following SAH, seven of nine monkeys became natriuretic and hyponatremic. The natriuretic period lasted an average of 4.4 +/- 0.4 days. The mean nadir of serum sodium content was 125.7 +/- 1.6 mEq/liter, and occurred on the average on the 5th day following SAH. The sodium balance after SAH was negative as compared to the preoperative positive sodium balance (p less than 0.001). The plasma vasopressin level was usually elevated for a day following surgery, but there was no significant difference in the levels during the preoperative period and during the period of natriuresis following SAH. The daily urine output and aldosterone levels were not significantly different, and the plasma volume was slightly, but not significantly, decreased after SAH. Four of the animals that had a hyponatremic and natriuretic response following SAH showed a normal regulation of vasopressin in response to both a water challenge and hypertonic saline challenge. The three monkeys that underwent sham procedures did not become hyponatremic and natriuretic postoperatively. The sham-operated monkeys did not show significant differences in their plasma vasopressin levels, urine volume, plasma volume, and aldosterone levels following surgery. These observations are more consistent with primary natriuresis as the cause of hyponatremia rather than the syndrome of inappropriate secretion of ADH. The cause of the renal loss of sodium is not known, but the possibility of a brain natriuretic factor or an alteration in the neural control of the kidney should be considered.

Arginine vasopressin levels in cerebrospinal fluid in neurological disease

Levels of arginine vasopressin have been measured in the blood and cerebrospinal fluid of patients with benign intracranial hypertension and raised intracranial pressure, patients with other neurological diseases and in normal control subjects. There was no difference in blood levels in each of the 3 groups (mean +/- SEM, 2.8 +/- 0.5, 2.5 +/- 0.25, 2.53 +/- 0.4 pg/ml). However, levels of arginine vasopressin in the cerebrospinal fluid in patients with benign intracranial hypertension and other neurological diseases were higher (mean +/- SEM, 0.64 +/- 0.005, 0.61 +/- 0.04 pg/ml), than in the control group (0.49 +/- 0.06), but not different from each other. The origin of arginine vasopressin in cerebrospinal fluid is uncertain and a number of possibilities are discussed.

Hyponatremia in intracranial disease: perhaps not the syndrome of inappropriate secretion of antidiuretic hormone (SIADH)

Patients with intracranial disorders are prone to develop hyponatremia with inability to prevent the loss of sodium in their urine. This was originally referred to as "cerebral salt wasting," but more recently is thought to be secondary to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Blood volume determinations were made in 12 unselected neurosurgical patients with intracranial disease who fulfilled the laboratory criteria for SIADH. Ten of the 12 patients had significant decreases in their red blood cell mass, plasma volume, and total blood volume. The finding of a decreased blood volume in patients who fulfill the laboratory criteria for SIADH is better explained by the original concepts of cerebral salt wasting than by SIADH. The primary defect may be the inability of the kidney to conserve sodium.

Elevations in plasma ADH levels during PEEP ventilation in the dog: mechanisms involved

In an attempt to define more precisely the various mechanisms involved in antidiuretic hormone (ADH) release during positive end-expiratory pressure ventilation (PEEP), experiments were performed on seven groups of dogs. PEEP-10 and PEEP-15 cmH2O caused significant elevations of plasma ADH from basal values of 24.9 +/- 5.2 pg/ml (mean +/- SE) to 64.6 +/- 14.2 and 106.0 +/- 20.6, respectively (P < 0.02, P < 0.005). The ADH levels returned to basal values after cessation of PEEP. This rise in ADH levels was prevented by an infusion of dextran prior to PEEP. The fall in blood pressure and cardiac output that occurred during PEEP was also prevented by the dextran infusion. Changes in ADH levels were unrelated to lung volume, left transmural pressure, and serum osmolality. Bilateral vagotomy and carotid sinus denervation was followed by an attenuated rise in ADH levels in terms of the percent rise above base line, but it did not significantly alter the absolute rise in ADH during PEEP. ADH levels were, however, reduced significantly by decreasing intracranial pressure by the removal of cerebrospinal fluid during PEEP. Propranolol administration prior to PEEP completely blocked plasma renin activity. Although the peak ADH levels were unaffected by propranolol, the rise was delayed. The results obtained indicate that a number of physiological factors may affect plasma ADH levels during PEEP. These include the carotid body and aortic arch baroreceptors as wells as sensors of intracranial pressure.