RESUMO
OBJECTIVE. The purpose of this study was to evaluate the level of agreement in diagnostic probability for selected phrases among radiologists and emergency medicine (EM) physicians. MATERIALS AND METHODS. A survey was distributed to the radiologists and EM physicians at our academic institution. Respondents selected the degree of diagnostic probability they believe was conveyed by 18 commonly used phrases chosen from studies in the radiology literature. Potential responses for the degree of diagnostic probability were < 10%, ≈ 25%, ≈ 50%, ≈ 75%, and > 90%. RESULTS. Seventy-eight percent (28/36) of EM residents and 56% (14/25) of EM attending physicians (combined fellows and attending physicians) completed the survey; 83% (15/18) of radiology residents and 81% (17/21) of radiology attending physicians completed the survey. There was a high degree of shared understanding for most phrases between the departments except for the phrase "compatible with," which was associated with a higher degree of diagnostic probability by radiologists than by EM physicians (p = .02). Although no term was significantly more specific than any other within the ≈ 50% category or below, "most likely" and "diagnostic of" were significantly more specific than other terms in the ≈ 75% and > 90% categories, respectively. CONCLUSION. The results of this study show a high degree of shared understanding between radiologists and EM physicians for most of the phrases (17/18) in the survey. The only phrase that showed a significant difference was "compatible with." These results can be used to generate diagnostic probability groups with suggested phrases that can be used when creating radiology reports, thereby improving communication with the emergency department.
Assuntos
Compreensão , Medicina de Emergência/estatística & dados numéricos , Prontuários Médicos , Corpo Clínico/estatística & dados numéricos , Radiologistas/estatística & dados numéricos , Terminologia como Assunto , Humanos , Internato e Residência/estatística & dados numéricos , Probabilidade , Inquéritos e Questionários/estatística & dados numéricosRESUMO
Collegiate football athletes are subject to repeated head impacts. The purpose of this study was to determine whether this exposure can lead to changes in brain structure. This prospective cohort study was conducted with up to 4 years of follow-up on 63 football (high-impact) and 34 volleyball (control) male collegiate athletes with a total of 315 MRI scans (after exclusions: football n â= â50, volleyball n â= â24, total scans â= â273) using high-resolution structural imaging. Volumetric and cortical thickness estimates were derived using FreeSurfer 5.3's longitudinal pipeline. A linear mixed-effects model assessed the effect of group (football vs. volleyball), time from baseline MRI, and the interaction between group and time. We confirmed an expected developmental decrement in cortical thickness and volume in our cohort (p â< â.001). Superimposed on this, total cortical gray matter volume (p â= â.03) and cortical thickness within the left hemisphere (p â= â.04) showed a group by time interaction, indicating less age-related volume reduction and thinning in football compared to volleyball athletes. At the regional level, sport by time interactions on thickness and volume were identified in the left orbitofrontal (p â= â.001), superior temporal (p â= â.001), and postcentral regions (p â< â.001). Additional cortical thickness interactions were found in the left temporal pole (p â= â.003) and cuneus (p â= â.005). At the regional level, we also found main effects of sport in football athletes characterized by reduced volume in the right hippocampus (p â= â.003), right superior parietal cortical gray (p â< â.001) and white matter (p â< â.001), and increased volume of the left pallidum (p â= â.002). Within football, cortical thickness was higher with greater years of prior play (left hemisphere p â= â.013, right hemisphere p â= â.005), and any history of concussion was associated with less cortical thinning (left hemisphere p â= â.010, right hemisphere p â= â.011). Additionally, both position-associated concussion risk (p â= â.002) and SCAT scores (p â= â.023) were associated with less of the expected volume decrement of deep gray structures. This prospective longitudinal study comparing football and volleyball athletes shows divergent age-related trajectories of cortical thinning, possibly reflecting an impact-related alteration of normal cortical development. This warrants future research into the underlying mechanisms of impacts to the head on cortical maturation.
Assuntos
Córtex Cerebral/diagnóstico por imagem , Córtex Cerebral/lesões , Futebol Americano/lesões , Adolescente , Adulto , Atletas , Encéfalo/diagnóstico por imagem , Concussão Encefálica/diagnóstico por imagem , Estudos de Coortes , Lateralidade Funcional , Substância Cinzenta/diagnóstico por imagem , Humanos , Estudos Longitudinais , Imageamento por Ressonância Magnética , Masculino , Estudos Prospectivos , Voleibol/lesões , Adulto JovemRESUMO
BACKGROUND AND OBJECTIVES: Repeated impacts in high-contact sports such as American football can affect the brain's microstructure, which can be studied using diffusion MRI. Most imaging studies are cross-sectional, do not include low-contact players as controls, or lack advanced tract-specific microstructural metrics. We aimed to investigate longitudinal changes in high-contact collegiate athletes compared with low-contact controls using advanced diffusion MRI and automated fiber quantification. METHODS: We examined brain microstructure in high-contact (football) and low-contact (volleyball) collegiate athletes with up to 4 years of follow-up. Inclusion criteria included university and team enrollment. Exclusion criteria included history of neurosurgery, severe brain injury, and major neurologic or substance abuse disorder. We investigated diffusion metrics along the length of tracts using nested linear mixed-effects models to ascertain the acute and chronic effects of subconcussive and concussive impacts, and associations between diffusion changes with clinical, behavioral, and sports-related measures. RESULTS: Forty-nine football and 24 volleyball players (271 total scans) were included. Football players had significantly divergent trajectories in multiple microstructural metrics and tracts. Longitudinal increases in fractional anisotropy and axonal water fraction, and decreases in radial/mean diffusivity and orientation dispersion index, were present in volleyball but absent in football players (all findings |T-statistic|> 3.5, p value <0.0001). This pattern was present in the callosum forceps minor, superior longitudinal fasciculus, thalamic radiation, and cingulum hippocampus. Longitudinal differences were more prominent and observed in more tracts in concussed football players (n = 24, |T|> 3.6, p < 0.0001). An analysis of immediate postconcussion scans (n = 12) demonstrated a transient localized increase in axial diffusivity and mean/radial kurtosis in the uncinate and cingulum hippocampus (|T| > 3.7, p < 0.0001). Finally, within football players, those with high position-based impact risk demonstrated increased intracellular volume fraction longitudinally (T = 3.6, p < 0.0001). DISCUSSION: The observed longitudinal changes seen in football, and especially concussed athletes, could reveal diminished myelination, altered axonal calibers, or depressed pruning processes leading to a static, nondecreasing axonal dispersion. This prospective longitudinal study demonstrates divergent tract-specific trajectories of brain microstructure, possibly reflecting a concussive and repeated subconcussive impact-related alteration of white matter development in football athletes.
Assuntos
Concussão Encefálica , Futebol Americano , Voleibol , Humanos , Estudos Transversais , Estudos Longitudinais , Estudos Prospectivos , Universidades , Concussão Encefálica/diagnóstico por imagemRESUMO
Aneurysmal bone cysts (ABC) are rare in the paranasal sinuses. They are benign expansile multicystic masses containing blood-filled spaces which typically occur in the long bones of pediatric patients. The lesion often produces symptoms due to the compression of adjacent structures or pathological fracture and depends on localization. In this case report, we discuss a 28-year-old female who presented with left-sided headache, left eye proptosis, and diplopia. Radiologic evaluation revealed a left paranasal sinus expansile multicystic mass with internal blood fluid levels displacing and thinning the left medial orbital wall which suggested the diagnosis of ABC. Radiologists should be familiar with and comfortable diagnosing ABC in the head and neck, and be able to differentiate this entity from others, such as telangiectatic osteosarcoma. Biopsy can be challenging since blood products may be the only material identified and may produce tissue that is difficult to interpret or misdiagnosed.
RESUMO
Background and Purpose: Athletes participating in high-contact sports experience repeated head trauma. Anatomical findings, such as a cavum septum pellucidum, prominent CSF spaces, and hippocampal volume reductions, have been observed in cases of mild traumatic brain injury. The extent to which these neuroanatomical findings are associated with high-contact sports is unknown. The purpose of this study was to determine whether there are subtle neuroanatomic differences between athletes participating in high-contact sports compared to low-contact athletic controls. Materials and Methods: We performed longitudinal structural brain MRI scans in 63 football (high-contact) and 34 volleyball (low-contact control) male collegiate athletes with up to 4 years of follow-up, evaluating a total of 315 MRI scans. Board-certified neuroradiologists performed semi-quantitative visual analysis of neuroanatomic findings, including: cavum septum pellucidum type and size, extent of perivascular spaces, prominence of CSF spaces, white matter hyperintensities, arterial spin labeling perfusion asymmetries, fractional anisotropy holes, and hippocampal size. Results: At baseline, cavum septum pellucidum length was greater in football compared to volleyball controls (p = 0.02). All other comparisons were statistically equivalent after multiple comparison correction. Within football at baseline, the following trends that did not survive multiple comparison correction were observed: more years of prior football exposure exhibited a trend toward more perivascular spaces (p = 0.03 uncorrected), and lower baseline Standardized Concussion Assessment Tool scores toward more perivascular spaces (p = 0.02 uncorrected) and a smaller right hippocampal size (p = 0.02 uncorrected). Conclusion: Head impacts in high-contact sport (football) athletes may be associated with increased cavum septum pellucidum length compared to low-contact sport (volleyball) athletic controls. Other investigated neuroradiology metrics were generally equivalent between sports.
RESUMO
Central skull base osteomyelitis is a rare entity that can demonstrate confounding radiologic, clinical, and laboratory data leading to a delay in diagnosis. The morbidity and mortality for skull base osteomyelitis are both high, thus a rapid diagnosis is required for appropriate treatment. In this case report, we discuss a 68-year-old male who presented with acute left facial nerve paralysis in the setting of chronic headache and left mucoid middle ear effusion. Radiologic evaluation revealed abnormal hypointense marrow of the central skull base on T1 weighted magnetic resonance imaging, preclival mass-like tissue, and short segment luminal narrowing of the left cervical ICA with mycotic aneurysm formation. Extensive workup via a multidisciplinary approach, including neurology, otolaryngology, neurosurgery and radiology led to a diagnosis of central skull base osteomyelitis. A familiarity of this disease process is important for the radiologist in order to facilitate appropriate patient referral and treatment. This case emphasizes the importance of considering this diagnosis in the setting of headache, cranial neuropathy, and abnormal skull base imaging with adjacent preclival soft tissue mass.
RESUMO
OBJECTIVE(S): To assess the incidence of central nervous system abnormalities in pediatric subjects with sensorineural hearing loss (SNHL). METHODS: One hundred forty-three pediatric subjects evaluated for SNHL at a single academic center from 2007 to 2014 were included and divided into eight diagnosis groups based on etiology of SNHL. One hundred forty-three age- and gender-matched control subjects with no known brain-related pathology or history of hearing loss were included as healthy controls for comparison. Two neuroradiologists independently evaluated magnetic resonance imaging (MRI) and computed tomography (CT) scans for each subject. Comparison of abnormal cerebral development was performed using an ordinal logistic regression model. Concordance between CT and MRI of the temporal bone was assessed using the kappa statistic. RESULTS: The etiologies of hearing loss in our cohort were 37.8% genetic, 12.6% infectious, 1.4% ototoxin-induced, and 48.3% idiopathic. Brain MRI revealed cerebral developmental abnormalities in defined regions in >30% of the SNHL cohort, significantly more than in normal-hearing pediatric controls. The Sylvian fissure, Virchow-Robin spaces, and lateral ventricles were most commonly affected. In the temporal bone, the percentage of subjects with concordant findings on CT and MRI was ≥92% across all anatomical structures. CONCLUSION: MRI revealed a high incidence of intracranial abnormalities, suggestive of aberrant development of auditory and nonauditory neural structures associated with SNHL. CT and MRI share a high degree of concordance in detecting temporal bone anomalies. Inclusion of MRI as part of the workup of congenital SNHL may facilitate the detection of developmental anomalies of the brain associated with SNHL.
Assuntos
Surdez , Perda Auditiva Neurossensorial , Malformações do Sistema Nervoso , Criança , Perda Auditiva Neurossensorial/diagnóstico por imagem , Perda Auditiva Neurossensorial/epidemiologia , Perda Auditiva Neurossensorial/etiologia , Humanos , Incidência , Estudos RetrospectivosRESUMO
Three months following a craniectomy and cranioplasty indicated for intraperenchymal hemorrhage, a 74-year-old male suffered a cerebrospinal fluid leak complicated by delayed tension pneumocephalus and declining neurologic status demonstrating a particularly rare complication of neurologic trauma and surgery. While with symptoms of a space occupying mass is the most common presentation, the patient presented cerebrospinal fluid leak prompting CT imaging and diagnosis. Urgent surgical decompression is necessary and was performed resulting in improved mental status.
RESUMO
Collegiate football athletes are subject to repeated traumatic brain injuriesthat may cause brain injury. The hippocampus is composed of several distinct subfields with possible differential susceptibility to injury. The aim of this study is to determine whether there are longitudinal changes in hippocampal subfield volume in collegiate football. A prospective cohort study was conducted over a 5-year period tracking 63 football and 34 volleyball male collegiate athletes. Athletes underwent high-resolution structural magnetic resonance imaging, and automated segmentation provided hippocampal subfield volumes. At baseline, football (n = 59) athletes demonstrated a smaller subiculum volume than volleyball (n = 32) athletes (-67.77 mm3; p = 0.012). A regression analysis performed within football athletes similarly demonstrated a smaller subiculum volume among those at increased concussion risk based on athlete position (p = 0.001). For the longitudinal analysis, a linear mixed-effects model assessed the interaction between sport and time, revealing a significant decrease in cornu ammonis area 1 (CA1) volume in football (n = 36) athletes without an in-study concussion compared to volleyball (n = 23) athletes (volume difference per year = -35.22 mm3; p = 0.005). This decrease in CA1 volume over time was significant when football athletes were examined in isolation from volleyball athletes (p = 0.011). Thus, this prospective, longitudinal study showed a decrease in CA1 volume over time in football athletes, in addition to baseline differences that were identified in the downstream subiculum. Hippocampal changes may be important to study in high-contact sports.
Assuntos
Concussão Encefálica/diagnóstico por imagem , Futebol Americano , Hipocampo/diagnóstico por imagem , Atletas , Humanos , Estudos Longitudinais , Imageamento por Ressonância Magnética , Masculino , Neuroimagem , Tamanho do Órgão/fisiologia , Estudantes , Universidades , VoleibolAssuntos
Neoplasias Meníngeas/patologia , Meningioma/patologia , Adulto , Lesões Encefálicas Traumáticas/complicações , Transtornos da Cefaleia/etiologia , Humanos , Fossa Infratemporal/patologia , Fossa Infratemporal/cirurgia , Imageamento por Ressonância Magnética , Masculino , Neoplasias Meníngeas/terapia , Meningioma/terapia , Radioterapia , Tomografia Computadorizada por Raios XRESUMO
OBJECTIVES: To determine the prevalence of radiographic and histologic superior semicircular canal dehiscence (SSCD) and posterior semicircular canal dehiscence (PSCD) and associated changes in temporal bone thickness in children aged 0 to 7 years. STUDY DESIGN: Retrospective chart review and histopathologic review of cadaveric bone specimens. SETTING: Two tertiary referral centers. PATIENTS: Children younger than 7 years who underwent high-resolution computed tomography scan including the temporal bones between 1998 and 2013 and temporal bones harvested from children younger than 7 years. INTERVENTION(S): Two hundred twenty-eight computed tomography studies and 58 temporal bone specimens were reviewed. Available patient demographics were tabulated. MAIN OUTCOME MEASURE(S): Prevalence of SSCD and PSCD and bone thickness over semicircular canals, with comparison across age groups. Clinical data were extracted for patients with radiographic dehiscence. RESULTS: Prevalence by ear of SSCD was 11.9%, 4.9%, 2.8%, and 0% and of PSCD was 16.7%, 2.4%, 1.4%, and 0% in children aged less than 6 months, 6 to 11 months, 12 to 35 months, and 3 to 7 years, respectively. SSCD was statistically more common before 1 year of age and PSCD before 6 months of age. Bone thickness overlying both the SSC and the PSC increased with age. Radiographic PSC bone was significantly thicker than SSC bone in patients older than 12 months. No dehiscences were found in the histologic specimens. CONCLUSION: Radiographic dehiscence of the canals is common in the first 6 months of life, with thin bone seen histologically. Prevalence decreases with increasing age as the bone overlying the canals increases in thickness.
Assuntos
Doenças do Labirinto/epidemiologia , Canais Semicirculares/diagnóstico por imagem , Osso Temporal/diagnóstico por imagem , Distribuição por Idade , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Humanos , Lactente , Doenças do Labirinto/diagnóstico por imagem , Doenças do Labirinto/patologia , Masculino , Prevalência , Projetos de Pesquisa , Estudos Retrospectivos , Canais Semicirculares/patologia , Osso Temporal/patologia , Tomografia Computadorizada por Raios XRESUMO
Lupus Mastitis (LM) is a rare presentation of lupus panniculitis involving the breast. Because it often presents as a tender palpable mass, a workup for malignancy usually ensues. It is well documented that surgery may worsen the condition; therefore, it is important to consider LM in the differential of a palpable breast mass in patients with systemic lupus erythematosus (SLE). Currently, management of LM remains primarily medical. We discuss the multi-disciplinary work-up of LM, and further describe its appearance on serial Magnetic Resonance (MR) exams.
Assuntos
Mama/patologia , Mastite/diagnóstico , Paniculite de Lúpus Eritematoso/diagnóstico , Adulto , Biópsia por Agulha , Diagnóstico Diferencial , Feminino , Humanos , Imageamento por Ressonância Magnética , Mamografia , Mastodinia/etiologiaRESUMO
The purpose of this study was to determine the prevalence of pulmonary embolism in outpatients who return to care with clinical suspicion of pulmonary embolism and are evaluated by computed tomography pulmonary angiogram (CTPA) after an initial CTPA was negative for pulmonary embolism within the preceding 12 months. Following institutional review board approval, we performed a retrospective review of all CTPAs performed at our institution from June 2006 through June 2009. One hundred and seventy-two outpatients [102 women; mean age 56.7±18.8 (SD)] with an initial CTPA that was negative for pulmonary embolism and a subsequent CTPA within 12 months of their initial study were included in our analysis. Each patient's CTPA was assessed for evidence of pulmonary embolism and their electronic medical records (EMR) reviewed for the presence of risk factors associated with venous thromboembolism (VTE). Fisher exact test (two-tailed) analysis was used to assess whether thromboembolic risk factors had an effect on developing pulmonary embolism after an initial negative CTPA. CTPAs were negative for pulmonary embolism in 165 (96%) of 172 outpatients who returned to care within 12 months after an initial negative CTPA. Eighty-five (49.4%) of 172 patients had no identified thromboembolic risk factors. In the group with no risk factors none (0%) of 85 patients (P=0.028) had pulmonary embolism at the time of repeat CTPA. This may help appropriately triage patients evaluated for pulmonary embolism and reduce the number of unnecessary CTPAs.
Assuntos
Embolia Pulmonar/diagnóstico , Tomografia Computadorizada por Raios X/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Angiografia/métodos , Feminino , Humanos , Pulmão/diagnóstico por imagem , Pulmão/patologia , Masculino , Pessoa de Meia-Idade , Pacientes Ambulatoriais , Artéria Pulmonar/diagnóstico por imagem , Embolia Pulmonar/diagnóstico por imagem , Estudos Retrospectivos , Fatores de Risco , Adulto JovemAssuntos
Hemorragia Ocular/etiologia , Neurilemoma/complicações , Neoplasias Orbitárias/complicações , Exoftalmia/etiologia , Exoftalmia/patologia , Hemorragia Ocular/patologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Neurilemoma/patologia , Neoplasias Orbitárias/diagnóstico , Neoplasias Orbitárias/patologia , Transtornos da Visão/etiologia , Transtornos da Visão/patologia , Adulto JovemRESUMO
We report a case of a previously healthy 33-year-old male who presented to his primary care physician with nausea, vomiting, diarrhoea and fever. One week prior to presentation the patient reported a history of sore throat which he presumed to be a viral infection and sought no medical attention. Upon hospital presentation, the patient was admitted and rapidly progressed to sepsis and respiratory failure. Goal directed therapy was initiated and the patient was intubated. Further clinical work up included blood cultures revealing Fusobacterium varium bacteraemia, and CT and ultrasound imaging demonstrated thrombosis of the internal jugular vein and septic pulmonary emboli. A diagnosis of Lemierre syndrome was made, and antibiotics as well as anticoagulation therapy were initiated. The patient's clinical condition improved with treatment, and he was discharged home on hospital day 12 with completion of an uneventful 4-week course of outpatient antibiotic and anticoagulation therapy.
Assuntos
Síndrome de Lemierre/complicações , Faringite/etiologia , Sepse/etiologia , Adulto , Antibacterianos/administração & dosagem , Antibacterianos/uso terapêutico , Anticoagulantes/administração & dosagem , Anticoagulantes/uso terapêutico , Diagnóstico Diferencial , Quimioterapia Combinada , Fusobacterium , Humanos , Síndrome de Lemierre/diagnóstico , Síndrome de Lemierre/diagnóstico por imagem , Síndrome de Lemierre/tratamento farmacológico , Pulmão/diagnóstico por imagem , Masculino , RadiografiaAssuntos
Abscesso/diagnóstico por imagem , Hematoma/diagnóstico por imagem , Doenças Testiculares/diagnóstico por imagem , Neoplasias Testiculares/diagnóstico por imagem , Testículo/diagnóstico por imagem , Testículo/lesões , Ultrassonografia Doppler em Cores , Ferimentos não Penetrantes/diagnóstico por imagem , Adulto , Diagnóstico Diferencial , Hematoma/cirurgia , Humanos , Masculino , Orquiectomia , Ferimentos não Penetrantes/cirurgiaRESUMO
BACKGROUND: Although forebrain pro-opiomelanocortin (POMC)-producing neurons seem to mediate or modulate many responses to ethanol consumption, changes in activity of this opiomelanocortinergic system in response to chronic ethanol consumption, withdrawal, and subsequent abstinence remain unresolved. METHODS: We investigated the effects of chronic daily ethanol consumption, withdrawal, and subsequent abstinence on adult male Sprague-Dawley rat forebrain opiomelanocortinergic activity as reflected by changes in hypothalamic POMC messenger RNA (mRNA) content by using a well characterized liquid diet model that we have previously demonstrated to accurately simulate not only daily oral ethanol consumption quantity and pattern, but also both neuroendocrine and behavioral changes characteristic of actively drinking and subsequently abstinent alcoholics. RESULTS: After 7 weeks of daily ethanol consumption at night and withdrawal during the day, evening mediobasal hypothalamus POMC mRNA concentrations were suppressed versus both ad libitum-fed and pair-fed controls. Morning POMC mRNA concentrations were also suppressed versus ad libitum-fed controls and tended to be decreased versus pair-fed controls. Three weeks after gradual removal of ethanol from the diet, mediobasal hypothalamus POMC mRNA concentrations were increased relative to ad libitum-fed and pair-fed controls. Plasma concentrations of corticosterone, testosterone, and leptin were also altered by the daily ethanol/withdrawal treatment and by subsequent abstinence. CONCLUSIONS: Because each of these hormones has been demonstrated to modify forebrain POMC gene expression under some conditions, the overall changes in forebrain opiomelanocortinergic regulation in response to chronic daily ethanol/withdrawal and subsequent abstinence probably reflect, at least in part, regulation by multiple endocrine mechanisms, together with responses to stress, development of tolerance during chronic daily ethanol consumption, and rebound of function after termination of this consumption. Overall, the demonstrated changes in forebrain POMC gene expression are consistent with significant roles for forebrain opiomelanocortinergic regulation in mediating alcohol dependence, propensity to relapse, and the alcohol deprivation effect.
Assuntos
Transtornos Relacionados ao Uso de Álcool/metabolismo , Depressores do Sistema Nervoso Central/administração & dosagem , Etanol/administração & dosagem , Regulação da Expressão Gênica/efeitos dos fármacos , Pró-Opiomelanocortina/biossíntese , Prosencéfalo/metabolismo , Síndrome de Abstinência a Substâncias/metabolismo , Animais , Esquema de Medicação , Regulação da Expressão Gênica/fisiologia , Leptina/sangue , Masculino , Pró-Opiomelanocortina/antagonistas & inibidores , Pró-Opiomelanocortina/genética , RNA Mensageiro/antagonistas & inibidores , RNA Mensageiro/biossíntese , Ratos , Ratos Sprague-Dawley , Recidiva , Temperança/estatística & dados numéricosRESUMO
Both plasma melatonin levels and hypothalamic arcuate nucleus pro-opiomelanocortin (POMC) (biosynthetic precursor to the endogenous opioid ss-endorphin and other opiomelanocortins) mRNA content decrease with aging. To test whether the decline in melatonin is responsible for the decline in POMC mRNA, we investigated the effects of daily melatonin treatment on hypothalamic POMC mRNA content in middle-aged and older Sprague-Dawley rats. Daily nocturnal melatonin treatment (50 microg kg bw(-1) night(-1), in the night-time drinking water) for 7 months, starting at 13 months of age, did not significantly alter female arcuate nucleus POMC mRNA content determined at the end of the light period (i.e., before nightly melatonin administration), but suppressed (24%, P < 0.05) POMC mRNA content at the end of the dark period (i.e., following melatonin administration). Likewise, nocturnal administration of 50 or 500 microg melatonin kg bw(-1) night(-1) to male rats for 7 months suppressed (31 or 28%, respectively; P < 0.05) POMC mRNA content at the middle of the dark period at 20 months of age. Finally, 10 wk administration of 30 microg melatonin kg bw(-1) day(-1) suppressed (31%, P < 0.01) POMC mRNA content in middle-aged male rats killed at the end of the dark period. Melatonin treatments did not significantly alter estradiol or testosterone levels. Thus, moderate-dosage nocturnal melatonin supplementation suppressed nocturnal hypothalamic POMC gene expression in both middle-aged males and females, suggesting that melatonin supplementation during aging decreases, rather than increases, forebrain opiomelanocortinergic activity. These POMC responses were apparently not dependent on gonadal steroid responses and did not become refractory to melatonin treatment maintained until old age.