Research challenges in central nervous system manifestations of inborn errors of metabolism.

The Research Challenges in CNS Manifestations of Inborn Errors of Metabolism workshop was designed to address challenges in translating potential therapies for these rare disorders, and to highlight novel therapeutic strategies and innovative approaches to CNS delivery, assessment of effects and directions for the future in the treatment of these diseases. Therapies for the brain in inborn errors represent some of the greatest challenges to translational research due to the special properties of the brain, and of inborn errors themselves. This review covers the proceedings of this workshop as submitted by participants. Scientific, ethical and regulatory issues are discussed, along with ways to measure outcomes and the conduct of clinical trials. Participants included regulatory and funding agencies, clinicians, scientists, industry and advocacy groups.

Further resolution of adult chick hemoglobins by isoelectric focusing in polyacrylamide gel.

Evidence is presented that adult chick hemoglobins exist in four types separable by isoelectric focusing on polyacrylamide gels instead of the two hemoglobin types previously resolved by other methods. These are hemoglobin A1 (HbA1), hemoglobin A2 (HbA2), hemoglobin D1 (HbD1), and hemoglobin D2(HbD2). Their pI values are 7.53 +/- 0.02, 7.37 +/- 0.02, 6.92 +/- 0.04 and 6.72 +/- 0.05, respectively, constituting about 63, 14, 18 and 5% of the total hemoglobin from adult chick erythrocytes, respectively. HbA1 and HbA2 ar identical in size, as determined on sodium dodecyl sulfate gels and similar in their amino acid composition and tryptic peptides. The molecular weight and amino acid composition of HbD1 and HbD2 are also identical although there are differences in their tryptic peptides. Experiments were done to show that the existence of four hemoglobin types is not due to genetic heterogeneity of the experimental animal, nor to artifacts of oxidation of carboxyhemoglobin to methemoglobin tetramers. Care was exercised to eliminate deamination and modification of side chain amino groups by using freshly prepared hemolysates and to minimize the "plateau phenomenon" peculiar to isoelectric focusing by controlling the duration of electrophoresis. The use of cyanmet form of (thus liganded) hemoglobin in this study reduced the chance of heterotetramer formation. Furthermore, consideration was given to possible anomalies caused by ampholytes. In the face of negative evidence for artifacts, it is concluded that adult chicken has more than the two hemoglobin types previously reported.

Prognostic factors and treatment results for supratentorial primitive neuroectodermal tumors in children using radiation and chemotherapy: a Childrens Cancer Group randomized trial.

PURPOSE: To determine clinical characteristics and response to treatment for children with supratentorial primitive neuroectodermal tumors (S-PNETs). PATIENTS AND METHODS: After surgery and staging, 55 patients aged 1.5 to 19.3 years with S-PNETs were randomized to receive craniospinal radiotherapy (RT) followed by eight cycles of 1-(2-chloro-ethyl)-3-cyclohexylnitrosourea (CCNU), vincristine (VCR), and prednisone (standard treatment) or two cycles of 8-in-1 chemotherapy followed by RT and then eight additional cycles of 8-in-1. RESULTS: Three-year Kaplan-Meier estimates (estimate +/- SE) of survival and progression-free survival (PFS) rates for patients with confirmed diagnoses of S-PNET were 57% +/- 8% and 45% +/- 8%, respectively; survival and PFS rates for children with PNETs located in the pineal region were 73% +/- 12% and 61% +/- 13%, respectively, and were significantly different from the other S-PNETs (P < .03). The 8-in-1 arm had greater toxicity than the standard-treatment arm. Distributions of PFS between the two treatment groups were not significantly different (P > .5). Other univariate prognostic factors that influenced PFS included metastasis (M) stage (P < .03: M0 50% +/- 9% v M1-4 0%) and age (P < .02: 1.5 to 2 years 25% +/- 13% v > or = 3 years 53% +/- 9%). CONCLUSION: In this first randomized treatment trial for S-PNETs in children, no significant differences were detected between the two treatment groups. M0 and pineal site of involvement were independent predictors of a better outcome. However, survival was better than previously reported.

Treatment of children with medulloblastomas with reduced-dose craniospinal radiation therapy and adjuvant chemotherapy: A Children's Cancer Group Study.

PURPOSE: Medulloblastoma is the most common malignant brain tumor of childhood. After treatment with surgery and radiation therapy, approximately 60% of children with medulloblastoma are alive and free of progressive disease 5 years after diagnosis, but many have significant neurocognitive sequelae. This study was undertaken to determine the feasibility and efficacy of treating children with nondisseminated medulloblastoma with reduced-dose craniospinal radiotherapy plus adjuvant chemotherapy. PATIENTS AND METHODS: Over a 3-year period, 65 children between 3 and 10 years of age with nondisseminated medulloblastoma were treated with postoperative, reduced-dose craniospinal radiation therapy (23.4 Gy) and 55.8 Gy of local radiation therapy. Adjuvant vincristine chemotherapy was administered during radiotherapy, and lomustine, vincristine, and cisplatin chemotherapy was administered during and after radiation. RESULTS: Progression-free survival was 86% +/- 4% at 3 years and 79% +/- 7% at 5 years. Sites of relapse for the 14 patients who developed progressive disease included the local tumor site alone in two patients, local tumor site and disseminated disease in nine, and nonprimary sites in three. Brainstem involvement did not adversely affect outcome. Therapy was relatively well tolerated; however, the dose of cisplatin had to be modified in more than 50% of patients before the completion of treatment. One child died of pneumonitis and sepsis during treatment. CONCLUSION: These overall survival rates compare favorably to those obtained in studies using full-dose radiation therapy alone or radiation therapy plus chemotherapy. The results suggest that reduced-dose craniospinal radiation therapy and adjuvant chemotherapy during and after radiation is a feasible approach for children with nondisseminated medulloblastoma.

Pilot study of high-dose thiotepa and etoposide with autologous bone marrow rescue in children and young adults with recurrent CNS tumors. The Children's Cancer Group.

PURPOSE: This study was designed to determine the toxicity, radiographic response rate, and outcome following high-dose thiotepa, etoposide, and autologous bone marrow rescue (ABMR) for young patients with recurrent malignant brain tumors. METHODS: Eligibility criteria required adequate renal, hepatic, and pulmonary function, and no bone marrow infiltration. Thiotepa 300 mg/m2 and etoposide 500 mg/ m2 were infused on 3 consecutive days, and autologous bone marrow was infused 72 hours following chemotherapy. RESULTS: Forty-five patients with recurrent high-grade brain tumors, aged 8 months to 36 years (median, 8 years), were treated. Seven patients (16%) died of treatment-related toxicities within 56 days of marrow reinfusion. Delayed platelet engraftment occurred in 44% of patients who survived beyond day 56. Of 35 patients with radiographically measurable disease who survived at least 28 days following ABMR, there were two complete responses (CRs) and six partial responses (PRs), for an overall response (CRs plus PRs) rate of 23% (SE = 7%). Objective responses were observed in four of 14 assessable patients with high-grade glioma and in two of six with primitive neuroectodermal tumors (PNETs)/ medulloblastoma. Survival was significantly improved in patients treated with minimal residual disease (P < .0005). Five of 18 patients (28%) with high-grade gliomas remain free of disease at 39+, 44+, 49+, 52+, and 59+ months post-ABMR. CONCLUSION: The combination of high-dose thiotepa and etoposide has activity against a variety of recurrent childhood brain tumors. These results merit further evaluation in children and young adults with both recurrent and newly diagnosed high-grade brain tumors.

Antipyrine metabolism in man: influence of age, alcohol, caffeine, and smoking.

Age has been shown to influence drug metabolism but effects of aging could be due to other variables that influence metabolism and differ with age. Plasma half-life and metabolic clearance rate of antipyrine were studied in 307 healthy male subjects, aged 18 to 92. Half-life was 16.5% longer and metabolic clearance rate was 18.5% less in a group of the older than in the younger subjects. Both caffeine and cigarette use were positively correlated with the rate of antipyrine metabolism. Multiple regression analysis showed that the effect of smoking was partially responsible for the age differences in antipyrine metabolism. Smoking explained 12% of the variance in metabolic clearance rate and age explained 3%. Our results suggest that studies attempting to quantify the effects of aging on drug metabolism must also take into account other factors that differ with age.

Progressive vision loss. A rare manifestation of familial cavernous angiomas.

We studied four generations of a family in which the index case had progressive loss of vision secondary to a cavernous angioma of the optic nerve and chiasm. Magnetic resonance imaging of the brain revealed multiple, asymptomatic intracerebral cavernous angiomas. Brain magnetic resonance imaging scans of the family members revealed multiple cavernous angiomas in the brother and paternal grandfather, but none in the father or his siblings. Autopsy reports of the paternal great grandfather noted multiple cavernous angiomas in the brain and abdominal viscera. We believe our patient to be the sixth reported case in which a cavernous angioma involved the optic chiasm and optic nerve. Magnetic resonance imaging is a sensitive and specific method of detecting cavernous angiomas. Cavernous angiomas have an autosomal dominant pattern of inheritance with variable penetrance. Surgical intervention in patients with symptomatic cavernous angiomas depends on the location and size of the lesion and associated surgical risks.

Gadolinium-DTPA-enhanced magnetic resonance imaging in childhood brain tumors.

Gadolinium DTPA (Gd-DTPA) is a paramagnetic blood-brain barrier contrast agent for MRI that has been used primarily in adults. During May through October 1987, 17 children between the ages of 3 and 18 years with brain tumors underwent MRI examinations, before and after Gd-DTPA (11 gliomas, 4 medulloblastomas, 1 craniopharyngioma, and 1 child with neurofibromatosis and no pathologic diagnosis). We compared T1 and T2 Gd-DTPA-enhanced MRI with concurrent unenhanced MRI and enhanced CT, and then correlated this with the clinical and pathologic findings. Gd-DTPA enhanced tumors in all 7 patients with newly diagnosed tumors and enhanced tumors in 7 of 10 patients without clinical evidence of progressive disease at the time of the study. In the 7 new patients, Gd-DTPA defined tumor margins in all, and demonstrated internal tumor architecture (vessels, necrosis, and cysts) in 5. Areas believed to represent surgical scars showed varying degrees of enhancement. Leptomeningeal tumor spread, including spinal, not seen on pre-Gd-DTPA MRI or on contrast CT, was evident in 2 patients. Gd-DTPA enhancement obscured hemorrhage within the tumor (methemoglobin) in 2 patients. There were no significant side effects. These results suggest that Gd-DTPA-enhanced MRI (1) is safe in children, (2) demonstrates the extent and character of tumors better than unenhanced MRI and enhanced CT, and (3) may allow for noninvasive imaging of leptomeningeal disease, including the spine, not previously demonstrated by any other noninvasive neuroimaging technique.

Outcome in elderly patients undergoing definitive surgery and radiation therapy for supratentorial glioblastoma multiforme at a tertiary care institution.

PURPOSE: To determine the efficacy of definitive surgery and radiation in patients aged 70 years and older with supratentorial glioblastoma multiforme. METHODS AND MATERIALS: We selected elderly patients (> or = 70 years) who had primary treatment for glioblastoma multiforme at our tertiary care institution from 1977 through 1996. The study group (n = 102) included 58 patients treated with definitive radiation, 19 treated with palliative radiation, and 25 who received no radiation. To compare our results with published findings, we grouped our patients according to the applicable prognostic categories developed by the Radiation Therapy Oncology Group (RTOG): RTOG group IV (n = 6), V (n = 70), and VI (n = 26). Patients were retrospectively assigned to prognostic group IV, V, or VI based on age, performance status, extent of surgery, mental status, neurologic function, and radiation dose. Treatment included surgical resection and radiation (n = 49), biopsy alone (n = 25), and biopsy followed by radiation (n = 28). Patients were also stratified according to whether they were optimally treated (gross total or subtotal resection with postoperative definitive radiation) or suboptimally treated (biopsy, biopsy + radiation, surgery alone, or surgery + palliative radiation). Patients were considered to have a favorable prognosis (n = 39) if they were optimally treated and had a Karnofsky Performance Status (KPS) score of at least 70. RESULTS: The median survival for patients according to RTOG groups IV, V, and VI was 9.2, 6.6, and 3.1 months, respectively (log-rank, p < 0.0004). The median overall survival was 5.3 months. The definitive radiation group (n = 58) had a median survival of 7.3 months compared to 4.5 months in the palliative radiation group (n = 19) and 1.2 months in the biopsy-alone group (p < 0.0001). Optimally treated patients had a median survival of 7.4 months compared to 2.4 months in those suboptimally treated (p < 0.0001). The favorable prognosis group had an 8.4-month median survival compared to 2.4 months in the unfavorable group (p < 0.0001). On multivariate analysis, the KPS, RTOG group, favorable/unfavorable prognosis, and optimal treatment/suboptimal treatment were significant predictors of survival. CONCLUSION: Elderly patients with good performance status (> or = 70 KPS) when treated aggressively with maximal resection and definitive radiation had longer survival than those treated with palliative radiation and biopsy. Aggressive treatment in such patients should be considered.

Estimating familial aggregation while adjusting for covariates. Application to pulmonary function data from black and white sibships.

Although crude correlations are useful in family studies, some adjustment for effects of risk factors that vary both within and among families if often needed. A linear model for estimating sibship correlations while simultaneously considering height, age, race, sex, ascertainment, and smoking status was used on pulmonary function data on 1-second forced expiratory volume (FEV1) and the natural logarithm of the ratio of FEV1 to forced vital capacity (lnFEV%) from 402 adults in 152 white sibships and 172 adults in 59 black sibships. Crude correlations of .271 +/- .048 (FEV1) and .342 +/- .047 (lnFEV%) decreased significantly to .206 +/- .048 and .231 +/- .048, respectively, after adjustment. For black and white sibs, adjusted intraclass correlations, although not statistically different, were .153 +/- .089 and .225 +/- .055 (FEV1), respectively, and were .103 +/- .088 and .275 +/- .054 (lnFEV%), respectively, suggesting that pulmonary function may aggregate more strongly among whites. This analysis illustrates how risk factor adjustment can be readily incorporated into familial correlation studies.

Applications of the concept of attributable fraction in medical genetics.

Attributable fraction, the fraction of cases of a disease in a population attributed to a particular risk factor, is a useful measure in the design and interpretation of epidemiologic studies of disease etiology. We review here the applications of the concept of attributable fraction in medical genetics. Specifically, attributable fraction can be used 1) in studies of the association between genetic traits and specific diseases to quantitate the contribution of specific alleles to disease occurrence in a population; 2) in population studies of mutations and birth defects to estimate the impact of mutagens and teratogens; and 3) in genetic analyses of family data, to evaluate the contribution of putative single gene loci to disease etiology. In the latter context, the concept of attributable fraction can be contrasted with the more commonly used concept of heritability. Examples from the literature provide illustrations of the usefulness of attributable fraction in medical genetic studies.

Variance components analysis of forced expiration in families.

Familial aggregation of forced expiration (as measured by forced expiratory volume in 1 sec (FEV1) and the ratio of this to total forced vital capacity (FEV1/FVC) was analyzed in 439 adult members of 108 families ascertained through control patients who had participated in a genetic and epidemiologic study of chronic obstructive pulmonary disease. Residual values for both FEV1 and FEV1/FVC obtained from regression on age, sex, race, and cigarette smoking (and height for FEV1) were used in a variance components analysis to assess the relative importance of genetic and nongenetic factors influencing familial aggregation of pulmonary function among adults. For both residual FEV1 and residual FEV1/FVC, the "best" model among a series of genetic and nongenetic models was a simple additive genetic model. A modified score test, which is robust to the assumption of multivariate normality, was used to test the significance of these estimated components. Under the most parsimonious model, additive genetic variation accounted for 28% of the variation in residual FEV1 in 108 families and 24% of the variation in residual FEV1/FVC. After outlying individuals were identified by examining goodness-of-fit statistics, the simple genetic model still gave the best fit to these data. There was little indication of non-normality in FEV1 in these families; however, FEV1/FVC did show evidence of non-normality when examining goodness-of-fit statistics. This genetic component contributing to the distribution of forced expiration may be a factor in the familial aggregation of certain respiratory diseases.

Ultrastructural examination of the axillary skin biopsy in the diagnosis of metabolic diseases.

There is little information in the literature regarding the usefulness of ultrastructural examination of axillary skin biopsies in the evaluation of metabolic diseases. This is a retrospective clinicopathologic review of 143 patients who underwent axillary skin biopsies as part of evaluations for metabolic disease. Twenty-three (16%) had abnormalities, classified as follows: mitochondrial (n = 12), lysosomal (n = 6), increased glycogen (n = 3), nonspecific cytoplasmic inclusions (n = 2), ceroid lipofuscinosis (n = 1), and intradermal giant cells containing vacuoles and tubular inclusions (n = 1). Muscle biopsies were performed in 13 of the 23 patients; 11 showed abnormalities, including those related to mitochondria (n = 4) and other nonspecific changes (n = 7). Two patients underwent postmortem examination. Follow-up was available in 21 patients. A clinical or biochemical diagnosis was reached in 11 patients: metachromatic leukodystrophy (n = 2), electron transport chain abnormalities (n = 2), glutaric aciduria type II (n = 1), Unverricht disease (n = 1), Lennox-Gastaut syndrome (n = 1), ketotic hypoglycemia of childhood (n = 1), probable Leigh disease (n = 1), 5-methyl tetrahydrofolate homocystine methyltransferase deficiency (n = 1), and pyruvate dehydrogenase deficiency (n = 1). Of the 120 patients with negative skin biopsy results, 29 had abnormal findings on muscle (n = 27), nerve (n = 7), or brain (n = 3) biopsies. One patient had an abnormal heart biopsy result, and 3 patients underwent postmortem examinations. Follow-up was obtained in 27 of 29 patients. Diagnoses were achieved in 15 patients: electron transport chain abnormalities (n = 5), cortical dysplasia (n = 3), myoclonic epilepsy (n = 1), leukodystrophy (n = 2), Pallister-Killian mosaic syndrome (n = 1), Rett syndrome (n = 1), Landau-Kleffner syndrome (n = 1), and mitochondrial cardiomyopathy (n = 1). In conclusion, axillary skin biopsy is helpful in the evaluation of some causes of metabolic disease, but often the findings are nonspecific. A negative biopsy result does not rule out the possibility of metabolic disease, but a positive result may provide direction for further evaluation.

Major genetic mechanisms in pulmonary function.

Regressive models were used to search for possible major gene effects on pulmonary function in two groups of families: one ascertained through patients with chronic obstructive pulmonary disease [COPD defined as forced expiratory volume in one second (FEV1) less than 70% forced vital capacity (FVC)] and the other ascertained through patients with non-pulmonary disorders. There were 85 COPD families with data on 270 individuals and 56 non-pulmonary families with data on 199 individuals. The analysis was done on residuals obtained from a regression of FEV1 on age, sex, race, height, and ascertainment group. Smoking status was incorporated directly as a covariate in the regressive models. Data on probands were excluded in this analysis as a partial correction for ascertainment bias. The best fitting model for the 85 COPD families included a major gene effect with sex specific variances, but no residual familial correlation. The best fitting model for the non-pulmonary families was one with no major gene effect and no residual familial correlation. Cigarette smoking was a significant covariate in both groups of families. Testing for heterogeneity showed a significant difference in the control of pulmonary function among these COPD and non-pulmonary families (X2 = 20.12 on 6 df; p = 0.0026). Major gene effects appear to be limited to these COPD families, while there was no evidence for major gene effects in the non-pulmonary families.

Genetic-environmental interactions in chronic airways obstruction.

To examine patterns of interaction between cigarette smoking and genetic factors in relation to airways obstruction, cross sectional data were analysed on 1787 white non-patient adult participants in a genetic-epidemiological study of airways obstruction (AO), defined as one-second forced expiratory volume FEV1 less than 68% of forced vital capacity FVC. Interaction was examined between smoking and each of four factors previously found to be related to AO: alpha-1 antitrypsin (PiZ allele), ABO blood groups (A antigen), ABH non-secretor status, and first degree relationship to a COPD or lung cancer patient. Multiple linear regression was used to test for interaction and adjust mean FEV1 (as a per cent of FVC) and prevalence of AO for age, sex, socioeconomic status, coffee and alcohol intake. Statistical interaction was observed between smoking (measured in pack-years) and two genetic factors (presence of blood A antigen and the family history). At higher pack-year levels, those individuals with the A antigen or the family history, but especially those with both factors had a much lower mean FEV1/FVC % and a much higher prevalence of AO than expected based on a simple additive model. On the other hand, there was no interaction between smoking and PiZ allele, or smoking and ABH secretor status. The findings suggest a possible biological interaction between cigarette smoke and the airways of individuals with blood group A antigen and familial lung disease. The findings also emphasize the role of genetic-environmental interactions in chronic diseases of multifactorial aetiology.

Spindle cell carcinoma of the conjunctiva.

Spindle cell carcinoma, a variant of squamous cell carcinoma, has long been recognized in numerous tissues (including the skin, the upper respiratory tract, the oral cavity, and the esophagus). Two cases of spindle cell carcinoma of the conjunctiva are reported here. Histopathologic examination of these cases shows the characteristic spindle-shaped cells in continuity with the overlying epithelium. Electron microscopy of one case showed desmosomes and cytoplasmic tonofibril-like material. Our direct experience with one of these two cases has shown the malignant neoplasm to be aggressive.

Diagnostic yield muscle biopsy in patients with clinical evidence of mitochondrial cytopathy.

We retrospectively reviewed 118 muscle biopsy specimens from 113 patients with clinical and/or biochemical evidence of mitochondrial cytopathy. Light microscopic evaluation revealed histologic abnormalities in 65 specimens. The most common histologic findings included angular atrophic esterase-positive muscle fibers, type II muscle atrophy, regenerating muscle fibers, and scattered cytochrome-oxidase deficient fibers. Ragged red fibers were noted in 3 specimens on a Gomori trichrome stain. Electron microscopic evaluation was performed in 113 muscle specimens, and in 34, no abnormalities were identified. Increased numbers of mitochondria, particularly in the subsarcolemmal region, were identified in 54 specimens. Increased mitochondrial size was seen in 8 specimens and paracrystalline mitochondrial inclusions in 3. Other ultrastructural findings included focally increased glycogen deposition, focal Z-band streaming, and focally increased lipid accumulation. For 39 cases, concomitant skin biopsy specimens were available; abnormalities were identified by electron microscopy in 12. The majority of biopsy specimens demonstrated some light or electron microscopic abnormality. Specific histologic findings suggestive of mitochondrial abnormalities (partial cytochrome oxidase deficiency, ragged red fibers) were noted in a minority of cases. Ultrastructural evidence of mitochondrial abnormalities was noted in the majority of cases.

Spinal MR findings in neurofibromatosis types 1 and 2.

PURPOSE: To evaluate the frequency and nature of spinal pathology, the frequency of clinically silent lesions, and the potential benefit of screening spinal MR in neurofibromatosis patients. PATIENTS AND METHODS: 28 neurofibromatosis type-1 (NF-1) patients and nine neurofibromatosis type-2 (NF-2) patients were studied with postcontrast spinal MR imaging. RESULTS: NF-1: One patient had a biopsy-proven low-grade glioma; five patients, intradural, extramedullary masses (N = 23); one patient, extradural masses (N = 2) (neurofibromas); 16 patients had bony abnormalities; and three patients thecal sac abnormalities. NF-2: Five patients demonstrated intramedullary masses (five/eight ependymomas); nine patients, intradural, extramedullary masses (meningiomas, schwannomas); and four patients, bony abnormalities. Eight/10 NF-1 and four/nine NF-2 patients had asymptomatic masses. CONCLUSION: Intradural disease is common, often asymptomatic, and often presents at a young age in NF-1 and NF-2 patients. Because of the propensity to develop significant asymptomatic as well as symptomatic intradural disease, screening of the entire spine with MR is recommended in both NF-1 and NF-2 patients.

Perceiver bias in the processing of human faces: neuropsychological mechanisms.

Previous research has suggested that in face-to-face contexts perceivers are biased to judge the side of the poser's face to their left as more similar to the full face than the side to their right. Traditional explanations of the perceiver bias have presumed that it is a visual field effect, with the side of the poser's face falling within the perceiver's left visual field dominating impressions of the full face. In this study, five experiments are reported. In the first experiment, the validity of the perceiver bias phenomenon was supported. The remaining experiments examined three alternative accounts of the neuropsychological processes that underlie the perceiver bias. No support was obtained for the visual field explanation, nor for an account of the bias as due to asymmetry in gaze patterns. Support was obtained for an account emphasizing a hemispatial bias in central processing. Despite equivalent intake of information from both sides of space, the brain may differentially weight information as a function of hemispatial origin. Practical and theoretical implications are discussed.

Multiple sleep latency test and polysomnography in diagnosing Kleine-Levin syndrome and periodic hypersomnia.

Kleine-Levin syndrome and periodic hypersomnia are often misdiagnosed initially because there is no objective test for these conditions. To determine the value of the Multiple Sleep Latency Test and polysomnography in this respect, the authors studied four patients with Kleine-Levin syndrome or periodic hypersomnia who had taken the Multiple Sleep Latency Test and undergone polysomnography during the symptomatic episode and/or during the asymptomatic interval. During but not between symptomatic episodes, the Multiple Sleep Latency Test revealed abnormal sleep latencies in all patients, and polysomnography revealed increased rapid eye movement propensity in one patient and a reduction in delta-sleep in two patients. In conclusion, the Multiple Sleep Latency Test and polysomnography are useful in diagnosing Kleine-Levin syndrome and periodic hypersomnia, especially when administered in a standardized fashion during and after the symptomatic period. The authors recommend that polysomnography and the Multiple Sleep Latency Test be performed no earlier than the second night after the onset of a symptomatic episode and the following day to reveal maximal hypersomnolence, and more than 2 weeks after a symptomatic episode to represent the asymptomatic interval.