Index of Suspicion

Abstract

A 10-year-old African American boy presents to the emergency department with 24-hour history of throbbing headaches, dizziness, blurry vision, nausea, and difficulty with arousal this morning. He has had no trauma or emesis. Three weeks earlier, he had undergone surgical correction of a leg-length discrepancy of the left tibia and fibula and the application of the Ilizarov external fixation device that required daily lengthening by 1 mm. There were no complications and he was discharged home on postoperative day 3. Past medical history and family history for hypertension are negative.At presentation, the boy's blood pressure is 190/106 mm Hg; he had normal readings throughout his hospital stay during and after surgery. His heart rate is 88 beats per minute, respiratory rate 20 breaths per minute, and oxygen saturation on room air 100%. He is afebrile and is not obese. On funduscopic examination, he has bilateral papilledema. His cardiac and respiratory findings are normal. His abdomen is soft without epigastric bruit, and no rash or striae are evident. His Glasgow Coma Scale score is 12, and there are no focal neurologic deficits.Laboratory findings are normal, including complete blood cell count and urinalysis, and levels of electrolytes, blood urea nitrogen, creatinine, catecholamines, plasma renin, and aldosterone, as are thyroid function tests. Renal ultrasonography shows normal kidneys and normal renal vasculature bilaterally. Echocardiography does not show left ventricular hypertrophy or suggestion of coarctation of the aorta.A 29-month-old boy presents to the emergency department following a 1-minute episode of unresponsiveness associated with whole body shaking, eye deviation, and urinary incontinence. Review of systems reveals recurrent emesis over the past 48 hours but no recent fever, foreign substance ingestion, or trauma.Physical examination demonstrates a developmentally appropriate, alert, and well-appearing boy who has normal vital signs, weight of 11.7 kg (10th percentile), height of 88 cm (25th percentile), and weight-for-length in the 15th percentile. He does not have any dysmorphic features or dermatologic findings, and has a normal neurologic evaluation.Laboratory investigation reveals a normal complete blood cell count and basic metabolic profile, with the exception of hyponatremia (sodium concentration 123 mmol/L).His past medical history is significant for failure to thrive at 12 months of age, suspected to be secondary to poor caloric intake and treated with a liquid nutritional supplement. In addition, he has a history of polyuria and polydipsia involving a daily consumption of 4 L of water beginning at 15 months of age. Management with fluid limitation resulted in severe temper tantrums.Because of the progression of polydipsia to nearly 7 L of water per day, he was diagnosed presumptively as having central diabetes insipidus (DI) and given once-daily desmopressin acetate at 26 months of age. The desmopressin acetate was successful initially at managing his symptoms, but owing to diminishing effect, the dose was increased to twice daily 2 months before his presentation. An additional test provides the final clues necessary to make the diagnosis.An 18-year-old girl presents to the emergency department with the acute onset of a sensation of a lump in her throat associated with painful swallowing. She was riding in a car when her symptoms began, and there is no history of sudden movements of the vehicle, nor was the vehicle involved in a crash. One week before presentation, she was snowboarding but denies trauma. She has not had fevers, sore throat, upper respiratory infection symptoms, cough, or vomiting. She denies swallowing a foreign body. She states she does have some pain in her upper chest with inspiration and with swallowing. The remainder of her review of systems is unremarkable, and she is otherwise healthy. She denies use of alcohol, tobacco, or illicit drugs. She does not play any musical instruments.Physical examination reveals a well-developed girl in no acute distress. Her temperature is 36°C, heart rate 85 beats per minute, blood pressure 127/69 mm Hg, respiratory rate 20 breaths per minute, and oxygen saturation 100% on room air. There is mild injection of the posterior pharynx without bleeding, erythema, or exudates and there is no edema of the uvula, tongue, or floor of the mouth. Her dentition is normal without gingival infection, abscess, missing teeth, or dental appliances. On neck evaluation, no subcutaneous emphysema or adenopathy is detected on palpation and the trachea is midline. The remainder of her examination is normal. Bedside nasopharyngolaryngoscopy performed by an otolaryngologist is unremarkable except for slight posterior pharyngeal bulging. An imaging study leads to the diagnosis.A lateral radiograph of the neck revealed retropharyngeal air (Fig. 1). The differential diagnosis included esophageal trauma from swallowing food or a foreign body, air tracking from the pleura owing to forced exhalation against a closed glottis, and infection, potentially from a retropharyngeal abscess. A barium swallow study showed no evidence of esophageal injury. Computed tomography of the soft tissues of the neck with contrast revealed air pockets in the superior mediastinum (Fig. 2). There was no evidence of fluid collection or edema, making infection in the retropharynx less likely. These radiologic findings, along with the patient’s relatively normal history and physical examination, were consistent with the diagnosis of spontaneous retropharyngeal emphysema (SRE).The patient was admitted for overnight observation. She was allowed to drink clear fluids and started on IV piperacillin/tazobactam. Repeat lateral neck radiographs demonstrated no progression of the emphysema. Her symptoms remained unchanged. She was discharged home in satisfactory condition with scheduled routine follow-up.SRE is an uncommon cause of dysphagia. No age or gender predilections have been reported. Typically, SRE is associated with acute increases in lung volume and consequent increases in pleural pressure, such as occurs with coughing, sneezing, or inhaled illicit drug usage. One proposed mechanism focuses on increased intra-alveolar pressure causing disruption of perivascular alveoli and subsequent dissection of air along the bronchovascular sheath and into the mediastinum. Once present in this area, air can track into the deep neck spaces and soft tissues as it follows the paths of least resistance. Patients with preexisting pulmonary conditions, such as asthma or respiratory infections, may be at higher risk for developing this condition.SRE is a diagnosis of exclusion, and life-threatening causes of retropharyngeal air, such as traumatic tracheoesophageal injury, suppurative or necrotizing deep neck and chest infections, and the effects of recent cervical or cardiothoracic surgery must be ruled out before making the diagnosis.Patients with SRE present with symptoms similar to those of pneumomediastinum, specifically the acute onset of sharp retrosternal chest pain with radiation. The pain often is aggravated by deep inspiration, lying down, and coughing. Patients also may experience dyspnea, but markedly increased work of breathing is uncommon unless there is progression with mediastinal involvement.Patients characteristically complain of throat discomfort, globus, dysphagia, or dysphonia. Physical findings vary, depending on the degree of soft tissue air extension, although physical examination usually is unremarkable. Crepitus in the precordial areas or decreased cardiac dullness on percussion may be present in this condition. A crunching sound over the precordium synchronous with the heartbeat (Hamman sign) would be a sign of a concomitant pneumomediastinum.Neck or chest radiography showing a column of retropharyngeal air and any accompanying pneumomediastinum usually are sufficient to confirm the diagnosis. Contrast studies, such as a barium swallow, or esophagoscopy should be considered when there is suspicion of pharyngeal or tracheoesophageal injury as the cause of the retropharyngeal air.The most critical management issue in patients who have retropharyngeal emphysema is to exclude life-threatening causes, such as esophageal perforation or necrotizing infection. SRE is a benign and self-limited condition. Treatment consists of analgesics and rest. Symptoms typically resolve over 2 to 3 days; however, retropharyngeal air can take several weeks to resorb completely. Antibiotics are not indicated unless an underlying infection is suspected (ie, pneumonia or retropharyngeal abscess).The patient was transferred to the ICU and started on intravenous (IV) phentolamine (0.05–0.1 mg/kg/dose) with gradual reduction in his blood pressure to 152/88 mm Hg over a few hours and return of his mental status to baseline. Improvement in blood pressure allowed transitioning from IV to oral medications with short-acting nifedipine 20 mg three times a day, resulting in readings of 130 to 140/80 to 90 mm Hg. At discharge 1 week later, his blood pressure was 130/86 mm Hg, thus requiring ongoing use of nifedipine. Follow-up blood pressure 3 months later, while still on the lengthening device, was still elevated at 128/80 mm Hg. On removal of the device 6 months later, his blood pressure normalized to 106/70 mm Hg, making the diagnosis of traction-induced hypertension likely.Hypertension is becoming more prevalent in children, and the increasing obesity prevalence, which now approaches 30%, is thought to be a contributing factor. In older children and adolescents, hypertension often is primary (essential hypertension) and managed first with diet and exercise. However, several factors should suggest that the hypertension might have an underlying cause, requiring detailed evaluation and management. Generally, the younger the patient and the higher the blood pressure, the more likely the hypertension is to be secondary.Secondary hypertension in children younger than 10 years old usually is attributable to renal parenchymal disease, renal vascular disease, endocrine causes, or coarctation of the aorta. Other, rarer, causes exist, such as traction-induced hypertension.Hypertensive emergency, defined as severe hypertension with end-organ damage, must be recognized and treated urgently regardless of the cause because there is a high mortality rate if left untreated. Blood pressures must be lowered slowly, and careful monitoring is required, usually in the ICU.Traction-induced hypertension is a well-documented but rare complication of orthopedic procedures, such as leg lengthening and skeletal traction. The proposed mechanism for the increase in blood pressure associated with leg lengthening is tension applied to the proximal third portion of the sciatic nerve. Experimental models have shown that the systemic arterial pressure rise associated with acute femoral lengthening is mediated by the sympathetic nervous system. Because the hypertension is mediated by sympathetic release secondary to sciatic nerve stretching, blocking this release with alpha-blockers is the most effective way of controlling the hypertension. Also, use of a beta-blocker alone should be avoided because the unopposed alpha stimulation potentially could worsen the hypertension.Most patients do not require modification of the traction because the blood pressure generally can be controlled with oral antihypertensive agents. Rarely is removal of the device required to treat refractory hypertension. When the traction device is removed, all patients become normotensive. Should hypertension persist, other causes should be sought.The symptomatic hyponatremia in this patient was managed by IV maintenance normal saline, enteral fluid restriction, and discontinuation of desmopressin acetate. Subsequently, his serum sodium level corrected and stabilized in the range of 140 mmol/L. Further investigation unveiled caregiver modeling of frequent water consumption, unrestricted access to water at home, and psychosocial stress related to recent paternal abandonment, leading to an acute worsening of the polydipsia. Additionally, bedside observation demonstrated heightened anxiety and excessive drinking behavior.Therefore, it was determined that a water deprivation test was necessary to distinguish DI from primary polydipsia as the underlying cause of his excessive drinking. Testing commenced at the time of the first urine void following initiation of fluid restriction. Baseline measurements included a serum sodium concentration of 139 mmol/L, urine specific gravity of 1.001, urine osmolality of 94 mOsm/kg, and serum osmolality of 284 mOsm/kg (urine-to-serum osmolality ratio of 0.3). During the testing period, urine specific gravity was measured hourly and weight was measured at 2-hour intervals.The water deprivation test was discontinued following the fourth hour, at which time repeat laboratory measurements revealed a serum sodium level of 143 mmol/L, urine specific gravity of 1.011, urine osmolality of 481 mOsm/kg, and serum osmolality of 292 mOsm/kg (urine-to-serum osmolality ratio of 1.6). These findings demonstrated a normal physiologic response to fluid restriction and, therefore, ruled out DI as the cause of his polydipsia. Furthermore, head magnetic resonance imaging demonstrated a normal, high-intensity signal of the posterior pituitary gland. Historical, laboratory, and radiographic evaluation combined with a thorough developmental assessment yielded the underlying diagnosis of primary polydipsia. The patient’s mother was counseled to limit his daily fluid intake and to discontinue use of desmopressin acetate.Salient etiologic considerations in children presenting with polyuria and polydipsia include diabetes mellitus, primary polydipsia (ie, psychogenic polydipsia or compulsive water drinking), and DI (congenital and acquired).DI can be categorized further into central (neurogenic) DI, which results from deficient production of arginine vasopressin (AVP, vasopressin, antidiuretic hormone) from the posterior pituitary gland, and nephrogenic DI, which results from AVP resistance at the level of the kidney. Although astute history gathering and basic laboratory data often can suggest DI, water deprivation testing remains the definitive method for establishing a diagnosis of DI. This test evaluates the integrity of water homeostasis through measurement of urine osmolality and serum osmolality during a period of fluid restriction.Test results consistent with DI include a persistently low urine osmolality despite a rising serum osmolality, which is signified by a urine-to-serum osmolality ratio of <1.5. Furthermore, water deprivation testing augmented by desmopressin acetate administration can distinguish central DI from nephrogenic DI. In both central and nephrogenic DI, water deprivation testing demonstrates failure to concentrate urine. However, desmopressin acetate administration will result in concentrated urine if DI is a consequence of a central process, but will have no effect in the case of nephrogenic DI. Water deprivation testing should be discontinued for weight loss ≥5%, urine specific gravity >1.014, or test duration >7 hours (>4 hours for infants).Patients who have polyuria and polydipsia resulting from primary polydipsia produce concentrated urine on water deprivation. Furthermore, circumventing the normal physiologic suppression of AVP in the setting of primary polydipsia by administration of exogenous vasopressin may lead to water intoxication syndrome, as occurred in this child. This condition results from water retention–induced hyponatremia, with subsequent cerebral edema. At sodium levels <125 mmol/L, patients may experience nausea, headache, encephalopathy, seizures, coma, or death.Primary polydipsia is reported commonly in the adult literature in association with schizophrenia and other psychiatric disorders, prompting the term psychogenic polydipsia. Although infrequent, primary polydipsia has been described in the pediatric literature also in the context of developmental disabilities, autism, and psychosocial stressors; however, primary polydipsia may be more common than reported.Although the cause of primary polydipsia is unclear, it is speculated to be caused by psychogenic factors or altered regulation of thirst. Physiologic thirst involves a complex and incompletely understood homeostatic mechanism. Thirst works in concert with a renal feedback system, and they comprise the two major regulators responsible for managing total body water. These complementary systems are triggered by rising osmolality detected by osmoreceptors located within the central nervous system, as well as by decreased effective circulating volume detected by baroreceptors located within the cardiovascular system.Signals are generated subsequently from the hypothalamus that simultaneously trigger thirst and generate the release of AVP from the posterior pituitary. AVP acts at the renal collecting duct to retain water via the aquaporin 2 water channel.Other factors influencing thirst involve social, environmental, psychological, and behavioral cues. These influences include association of beverages with meals and other activities; beverage availability, taste, and temperature; modeling and encouragement of beverage drinking by caretakers; and drinking habits. Any of these factors has the potential to function in a maladaptive manner and override normal thirst regulation.Primary polydipsia is characterized by excessive water consumption that results in hypervolemic hyponatremia and low serum osmolality, therefore triggering physiologic AVP suppression, which produces dilute urine.Treatment of primary polydipsia consists of fluid restriction to normal physiologic daily requirements for weight, not to exceed twice maintenance. This goal can be achieved gradually over the course of a few days to minimize resistance. Multiple behavioral strategies can be used, depending on the patient’s impetus to drink. In this patient, therapy consisted of the mother’s regulation of fluid intake and provision of alternative means of oral stimulation. Reward systems and cognitive behavioral therapy are other options, depending on the developmental stage of the individual. In addition, stability of the parent-child relationship is important to consider; therapy is aimed at stress reduction and improving family dynamics and child well-being.