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Hypoxia and hypercapnia in infants with mild laryngomalacia
ABSTRACTS
apy. If replicated by other investigators, this modality may prove useful in superficial lesions because of the energy of applied photons. Another therapeutic application would be its use in patients with multiple lesions or lesions overlying vital structures. Further studies with human squamous carcinoma cell lines, in vitro and in vivo, should be conducted before this technique is investigated in humans. Nevertheless, this is an irradiation technique that warrants attention Molecular Biology of Brain Tumors. JD McDonald, Dohrmann. Neurosurgery 1988; 23:537-544
GJ
This is a review article on the molecular biology of brain tumors. Although the focus of discussion is centered on brain tumors, it is a nice review of current techniques, problems, and advances in molecular biology as applied to the general problem of neoplasia. Specific examples of recent work on tumors using basic techniques-Southern and Northern blots, restricted enzyme digestion of DNA, molecular cloning of genes, and mapping of chromosomal lesions-are reviewed. In addition, oncogene control mechanisms in tumor cells are discussed. The more recent concept of recessive oncogenes is considered in relation to studies using patients with bilateral acoustic neurinomas and retinoblastoma. This article is a valuable summary of the most recent types of laboratory investigations that are also being applied to head and neck tumors. Future clinical implications of the findings are also discussed. For example, a standard part of the current staging of some solid tumors (eg, neuroblastoma) includes following the levels of oncogene copy number. Similarly, work on the amplification of growth factor receptors in tumor cells may guide the development of future treatment strategies. The study of recessive oncogenes in acoustic neurinoma is of more immediate clinical importance. These findings are consistent with the possibility that a lesion on chromosome 22 may represent the primary event in the pathogenesis of some acoustic neurinomas. The localization of the gene or genes involved should lead to advances in prenatal diagnosis. In short, this paper is a succinct summary of the role of molecular biology and its application in understanding the process of neoplasia, as well as the clinical issues involved. Magnetic Resonance Imaging of the Head and Neck Region. HG Jacobson. JAMA 1988; vol 260. Magnetic resonance imaging (MRI) is increasingly being used in the head and neck region, and in some cases replaces computed tomography (CT) imaging. This article reviews the major strengths and weaknesses of MRI of the extracranial head and neck structures. MRI and CT should be complementary, rather than exclusive, modalities. The major strengths of MRI include excellent cell-tissue contrast, noninvasiveness, and lack of ionizing radiation. The improved contrast resolution of MRI over CT has led to
greater sensitivity in studying individual pathways of cranial nerves in the posterior fossa. MRI is also very useful in vascular lesions because of its slow sensitive gradient--echo pulse sequences. The potential use of rapid scanning techniques in conjunction with paramagnetic contrast agents may produce imaging similar in quality and content to dynamic, contrast-enhanced CT scans. MRI has fundamental limitations for showing bone detail; in this regard, CT is still the favored imaging modality. However, MRI can be very sensitive in assessing the infiltration of lesions into the bone marrow. MRIs are excellent in viewing pathology of the skull base, salivary glands, paranasal sinuses, temporal bone, and orbit. It is noted that MRIs are expensive, and the additional information gained, when compared with other techniques, may not always justify the cost. Although some current papers enthusiastically suggest that MRI should be the radiographic examination of choice, such advocacy should be seen in the context of the critical information presented in this paper. Continued attention to clinical correlation is necessary in the next few years to see if this technique is indeed as excellent as it initially appears to be. Role of Ionizing Irradiation for 393 Keloids. TL Borok, M Bray, I Sinclair, et al. Int J Radiat Oncol Biol Phys 1988; 15:865-870 This paper documents the 58-year experience of one institution in the treatment of 393 keloids scattered over different sites. It is a retrospective chart review examining recurrence rates, cosmetic results, and radiation-induced neoplasia. Indications for offering radiation included keloid at the original treatment site (88%), documented multiple significant keloid formation (I%), and a strong family history of keloid formation (l%]. The most commonly given dose was 900 to 1,000 cGy. The most common site of recurrence following excision was in the ear lobes of young females with pierced ears. Recurrence rate after radiation was low (2.4%) and the cosmetic result was considered excellent in approximately 92%. Significant complications were limited to persistent pigment disturbance in only one patient. In this series, no cases of neoplasia were seen, although it is unclear whether there was a 100% follow-up for all the cases studied. This is an interesting study that would support the use of radiation therapy when keloid formation is a concern. However, a strict comparison between this technique and steroid injection has not been made. In addition, one should view with great caution the use of low-dose irradiation in young people in the treatment of a primarily cosmetic problem. Hypoxia and Hypercapnia in Infants with Mild Laryngomalacia. PB McCray, DM Crockett, et al. Am J Dis Child 1988; 142:896-899 Laryngomalacia accounts for more than 75% of cases of congenital stridor and is the most common
Volume 10 Number
4
July 1989 295
ABSTRACTS cause of partial obstruction in infants. Although the majority of infants do well with this laryngeal problem, there has been some concern for potentially serious complications due to intermittent upper airway obstruction with episodes of hypoxia and hypercapnia. Some complications reported with laryngomalacia include pulmonary hypertension, airway obstruction, sudden death, and failure to thrive. This study from the University of Iowa Hospitals examines the potential clinical importance of recurrent hypoxia and hypercapnia episodes by comparing patients with laryngomalacia with normal infants. Patients with laryngomalacia all underwent endoscopy by a pediatric otolaryngologist. It should be noted that the control infants did not undergo laryngoscopy. Following laryngoscopy, all patients were admitted overnight and underwent continuous measurement of transcutaneous PCO,. It was found that the control group of patients had a greater mean weight then the laryngomalacia patients. Episodes of hypercapnia and/or hypoxia occurred in 12 patients with laryngomalacia v eight control infants. Infants with laryngomalacia had significantly more episodes than did control infants. A history and physical examination did not distinguish those infants with laryngomalacia who had hypercapnia and/or hypoxia from those without such episodes. At follow-up (2 to 15 months) the symptoms were unchanged or improved in 13 patients with laryngomalacia, and 12 of the 13 showed normal growth without developmental delay or other complications. This study demonstrates that episodes of hypercapnia and combined hypoxiahypercapnia occur more often in patients with laryngomalacia than in control infants. The frequency of these episodes was variable in both groups. It was further concluded that screening with overnight 0, and CO, monitors is unlikely to predict a risk for complications because of the variable nature of such episodes in both groups. Moreover, a history and physical were not predictive of which group of patients would suffer complications. The results of this study raise questions regarding the management of infants with laryngomalacia. While the overall incidence of complications in laryngomalacia is unknown, it is presumably low and may require a large number of infants to accurately assess. It seems reasonable at this time to reassure parents that patients will outgrow the stridor. It does not seem likely that transcutaneous monitoring will distinguish which patients are likely to encounter future problems. Routine clinical follow-up at frequent intervals, monthly for 6 months and then every 2 to 3 months, should continue until the problem is resolved. This is a welldocumented study with the assistance of a pediatric otolaryngologist. It points out that although the apparent risk for complications is low, careful clinical follow-up is necessary in this group of patients. American Journal of Otolaryngology 296
Are Routine Preoperative Laboratory Screening Tests Necessary to Evaluate Ambulatory Surgical Patients? H Johnson, S Knee-Ioli, et al. Surgery 1988; 104:639-645
With increased emphasis on the containment of health care cost, the numbers of ambulatory surgical procedures are expected to grow into the next decade. In the 3 years from 1980 to 1983,there was a 55% increase in such procedures. An increase in ambulatory care services has led to the establishment of regulatory guidelines that call for identifying problems in patients undergoing surgical procedures, and whether they need to be hospitalized. This study prospectively examined 212 consecutive adult patients undergoing a variety of ambulatory surgical procedures. Routine preoperative urinalyses (UA), complete blood cell counts (CBC), and ECGs were studied to see if they were useful in determining the outcome of treatment. Urinalyses were abnormal in 39% of patients, CBCs were abnormal in go%,, and ECGs were abnormal in 66% of patients. However, the majority of patients with abnormalities determined by laboratory testing would have had such abnormalities predicted on the basis of history and physical exams alone. Surprisingly, abnormalities indicated by laboratory tests did not influence preoperative cancellation, postoperative complications, or admission to the hospital from the ambulatory unit. In the hospital where this study was performed, the cost of the mandatory screening was $92.00 per patient. It was estimated that even if only one quarter of the adult American population being treated in ambulatory surgical programs underwent these minimal screening tests, $113 million would be spent annually for a battery of tests providing little additional clinical information. The authors conclude that routine ECGs, UAs, and CBCs done on ambulatory surgical patients may show abnormalities, but that these abnormalities should be predictable by a good history and physical examination. Simple dipstick UA and spun hematocrits should replace the more expensive laboratory exams. ECGs should be performed only if suggested by the history and physical examination. Most of the surgical procedures performed in this study were on ASA class 1 or 2 patients who, as pointed out in the discussion, were referred to surgeons by internists. It is to be presumed, therefore, that these patients had previous medical screening before coming to surgery. This provocative study suggests that a standard history and physical examination provides the most valuable screening information for ambulatory surgical patients. This report should be read by any surgeon performing outpatient or ambulatory surgical procedures, since increases in regulations by third-party payers are establishing guidelines for patient care. Studies such as this may help determine future standards of care.
Electrical Stimulation of Onlay Bone Grafts. MC Stalnecker, LA Whitaker, CT Brighton. struct Surg 1988;82:580-588
Plastic
Recon-
The use of electrical stimulation to promote bone growth and repair has been studied extensively, and is currently in use for healing fracture non-union and congenital pseudarthroses when more traditional
apy. If replicated by other investigators, this modality may prove useful in superficial lesions because of the energy of applied photons. Another therapeutic application would be its use in patients with multiple lesions or lesions overlying vital structures. Further studies with human squamous carcinoma cell lines, in vitro and in vivo, should be conducted before this technique is investigated in humans. Nevertheless, this is an irradiation technique that warrants attention Molecular Biology of Brain Tumors. JD McDonald, Dohrmann. Neurosurgery 1988; 23:537-544
GJ
This is a review article on the molecular biology of brain tumors. Although the focus of discussion is centered on brain tumors, it is a nice review of current techniques, problems, and advances in molecular biology as applied to the general problem of neoplasia. Specific examples of recent work on tumors using basic techniques-Southern and Northern blots, restricted enzyme digestion of DNA, molecular cloning of genes, and mapping of chromosomal lesions-are reviewed. In addition, oncogene control mechanisms in tumor cells are discussed. The more recent concept of recessive oncogenes is considered in relation to studies using patients with bilateral acoustic neurinomas and retinoblastoma. This article is a valuable summary of the most recent types of laboratory investigations that are also being applied to head and neck tumors. Future clinical implications of the findings are also discussed. For example, a standard part of the current staging of some solid tumors (eg, neuroblastoma) includes following the levels of oncogene copy number. Similarly, work on the amplification of growth factor receptors in tumor cells may guide the development of future treatment strategies. The study of recessive oncogenes in acoustic neurinoma is of more immediate clinical importance. These findings are consistent with the possibility that a lesion on chromosome 22 may represent the primary event in the pathogenesis of some acoustic neurinomas. The localization of the gene or genes involved should lead to advances in prenatal diagnosis. In short, this paper is a succinct summary of the role of molecular biology and its application in understanding the process of neoplasia, as well as the clinical issues involved. Magnetic Resonance Imaging of the Head and Neck Region. HG Jacobson. JAMA 1988; vol 260. Magnetic resonance imaging (MRI) is increasingly being used in the head and neck region, and in some cases replaces computed tomography (CT) imaging. This article reviews the major strengths and weaknesses of MRI of the extracranial head and neck structures. MRI and CT should be complementary, rather than exclusive, modalities. The major strengths of MRI include excellent cell-tissue contrast, noninvasiveness, and lack of ionizing radiation. The improved contrast resolution of MRI over CT has led to
greater sensitivity in studying individual pathways of cranial nerves in the posterior fossa. MRI is also very useful in vascular lesions because of its slow sensitive gradient--echo pulse sequences. The potential use of rapid scanning techniques in conjunction with paramagnetic contrast agents may produce imaging similar in quality and content to dynamic, contrast-enhanced CT scans. MRI has fundamental limitations for showing bone detail; in this regard, CT is still the favored imaging modality. However, MRI can be very sensitive in assessing the infiltration of lesions into the bone marrow. MRIs are excellent in viewing pathology of the skull base, salivary glands, paranasal sinuses, temporal bone, and orbit. It is noted that MRIs are expensive, and the additional information gained, when compared with other techniques, may not always justify the cost. Although some current papers enthusiastically suggest that MRI should be the radiographic examination of choice, such advocacy should be seen in the context of the critical information presented in this paper. Continued attention to clinical correlation is necessary in the next few years to see if this technique is indeed as excellent as it initially appears to be. Role of Ionizing Irradiation for 393 Keloids. TL Borok, M Bray, I Sinclair, et al. Int J Radiat Oncol Biol Phys 1988; 15:865-870 This paper documents the 58-year experience of one institution in the treatment of 393 keloids scattered over different sites. It is a retrospective chart review examining recurrence rates, cosmetic results, and radiation-induced neoplasia. Indications for offering radiation included keloid at the original treatment site (88%), documented multiple significant keloid formation (I%), and a strong family history of keloid formation (l%]. The most commonly given dose was 900 to 1,000 cGy. The most common site of recurrence following excision was in the ear lobes of young females with pierced ears. Recurrence rate after radiation was low (2.4%) and the cosmetic result was considered excellent in approximately 92%. Significant complications were limited to persistent pigment disturbance in only one patient. In this series, no cases of neoplasia were seen, although it is unclear whether there was a 100% follow-up for all the cases studied. This is an interesting study that would support the use of radiation therapy when keloid formation is a concern. However, a strict comparison between this technique and steroid injection has not been made. In addition, one should view with great caution the use of low-dose irradiation in young people in the treatment of a primarily cosmetic problem. Hypoxia and Hypercapnia in Infants with Mild Laryngomalacia. PB McCray, DM Crockett, et al. Am J Dis Child 1988; 142:896-899 Laryngomalacia accounts for more than 75% of cases of congenital stridor and is the most common
Volume 10 Number
4
July 1989 295
ABSTRACTS cause of partial obstruction in infants. Although the majority of infants do well with this laryngeal problem, there has been some concern for potentially serious complications due to intermittent upper airway obstruction with episodes of hypoxia and hypercapnia. Some complications reported with laryngomalacia include pulmonary hypertension, airway obstruction, sudden death, and failure to thrive. This study from the University of Iowa Hospitals examines the potential clinical importance of recurrent hypoxia and hypercapnia episodes by comparing patients with laryngomalacia with normal infants. Patients with laryngomalacia all underwent endoscopy by a pediatric otolaryngologist. It should be noted that the control infants did not undergo laryngoscopy. Following laryngoscopy, all patients were admitted overnight and underwent continuous measurement of transcutaneous PCO,. It was found that the control group of patients had a greater mean weight then the laryngomalacia patients. Episodes of hypercapnia and/or hypoxia occurred in 12 patients with laryngomalacia v eight control infants. Infants with laryngomalacia had significantly more episodes than did control infants. A history and physical examination did not distinguish those infants with laryngomalacia who had hypercapnia and/or hypoxia from those without such episodes. At follow-up (2 to 15 months) the symptoms were unchanged or improved in 13 patients with laryngomalacia, and 12 of the 13 showed normal growth without developmental delay or other complications. This study demonstrates that episodes of hypercapnia and combined hypoxiahypercapnia occur more often in patients with laryngomalacia than in control infants. The frequency of these episodes was variable in both groups. It was further concluded that screening with overnight 0, and CO, monitors is unlikely to predict a risk for complications because of the variable nature of such episodes in both groups. Moreover, a history and physical were not predictive of which group of patients would suffer complications. The results of this study raise questions regarding the management of infants with laryngomalacia. While the overall incidence of complications in laryngomalacia is unknown, it is presumably low and may require a large number of infants to accurately assess. It seems reasonable at this time to reassure parents that patients will outgrow the stridor. It does not seem likely that transcutaneous monitoring will distinguish which patients are likely to encounter future problems. Routine clinical follow-up at frequent intervals, monthly for 6 months and then every 2 to 3 months, should continue until the problem is resolved. This is a welldocumented study with the assistance of a pediatric otolaryngologist. It points out that although the apparent risk for complications is low, careful clinical follow-up is necessary in this group of patients. American Journal of Otolaryngology 296
Are Routine Preoperative Laboratory Screening Tests Necessary to Evaluate Ambulatory Surgical Patients? H Johnson, S Knee-Ioli, et al. Surgery 1988; 104:639-645
With increased emphasis on the containment of health care cost, the numbers of ambulatory surgical procedures are expected to grow into the next decade. In the 3 years from 1980 to 1983,there was a 55% increase in such procedures. An increase in ambulatory care services has led to the establishment of regulatory guidelines that call for identifying problems in patients undergoing surgical procedures, and whether they need to be hospitalized. This study prospectively examined 212 consecutive adult patients undergoing a variety of ambulatory surgical procedures. Routine preoperative urinalyses (UA), complete blood cell counts (CBC), and ECGs were studied to see if they were useful in determining the outcome of treatment. Urinalyses were abnormal in 39% of patients, CBCs were abnormal in go%,, and ECGs were abnormal in 66% of patients. However, the majority of patients with abnormalities determined by laboratory testing would have had such abnormalities predicted on the basis of history and physical exams alone. Surprisingly, abnormalities indicated by laboratory tests did not influence preoperative cancellation, postoperative complications, or admission to the hospital from the ambulatory unit. In the hospital where this study was performed, the cost of the mandatory screening was $92.00 per patient. It was estimated that even if only one quarter of the adult American population being treated in ambulatory surgical programs underwent these minimal screening tests, $113 million would be spent annually for a battery of tests providing little additional clinical information. The authors conclude that routine ECGs, UAs, and CBCs done on ambulatory surgical patients may show abnormalities, but that these abnormalities should be predictable by a good history and physical examination. Simple dipstick UA and spun hematocrits should replace the more expensive laboratory exams. ECGs should be performed only if suggested by the history and physical examination. Most of the surgical procedures performed in this study were on ASA class 1 or 2 patients who, as pointed out in the discussion, were referred to surgeons by internists. It is to be presumed, therefore, that these patients had previous medical screening before coming to surgery. This provocative study suggests that a standard history and physical examination provides the most valuable screening information for ambulatory surgical patients. This report should be read by any surgeon performing outpatient or ambulatory surgical procedures, since increases in regulations by third-party payers are establishing guidelines for patient care. Studies such as this may help determine future standards of care.
Electrical Stimulation of Onlay Bone Grafts. MC Stalnecker, LA Whitaker, CT Brighton. struct Surg 1988;82:580-588
Plastic
Recon-
The use of electrical stimulation to promote bone growth and repair has been studied extensively, and is currently in use for healing fracture non-union and congenital pseudarthroses when more traditional