Typical Radiological Findings Research Articles

Can a diagnosis of multiple sclerosis be made without ruling out neuromyelitis optica spectrum disorder ?

BackgroundThe symptoms of multiple sclerosis (MS) can overlap with neuromyelitis optica spectrum disorder (NMOSD). Although testing is available for aquaporin 4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) antibodies, screening for NMOSD is recommended but not mandatory to establish a diagnosis of MS. Methods and resultsWe queried 319,994 individuals who filed claims for MS and NMOSD in a Truven Health Analytics (THA) database and had at least one year of uninterrupted health insurance coverage. Of this cohort, 2001 (0.62%) were diagnosed as having NMOSD after an initial diagnosis of MS, based on ICD 9/10 codes. Since THA only offers claims-based data, we initiated an individual patient-based data search at our medical center to screen for potential misdiagnoses. We identified 4/54 (7.4%) NMOSD cases that were initially diagnosed as having MS. ConclusionsThe results from our small study have significant implications––symptoms, clinical presentation or classic radiological findings perhaps cannot reliably separate MS from NMOSD. If our study findings can be replicated, guidelines to diagnose MS ought to recommend that NMOSD be excluded first despite typical clinical and radiological findings pointing to MS.

Tumoral calcinosis simulating sarcoma

Tumoral calcinosis is a rare clinical and pathological entity, characterized by deposition of calcium in different sites of human body particularly in peri-articular tissues. It incidence is usually seen in young adults as a slowly growing, painless, firm to bony hard mass. Asymptomatic when small in size but larger masses can cause pressure symptoms due to compression of surrounding tissues or restriction of mobility of the joints. It can be predicted by typical radiological findings with the help of serum calcium and phosphorus levels but is confirmed only by histopathological examination. Many times, it isn’t very easy to diagnose this condition preoperatively and can be mistaken as soft tissue sarcoma both clinically and radiologically. Subtyping of this lesion depends on serum calcium, phosphorus levels, family history and co-morbid conditions like chronic renal failure. Hemodialysis, hypervitaminosis-D, milk-alkali syndrome, hyperparathyroidism, etc are responsible for the secondary causes. Treatment modality depends on the subtype, which can be medical or by surgical intervention. The present study was a case of adolescent male with a slowly growing swelling over the right hip region for 4 years. There was no traumatic history or any significant family history. Serum calcium and phosphorus levels were within normal limits. Radiology showed well-demarcated lobulated solid-cystic mass swelling measuring 7.8x3.9x3.5cm suggestive of sarcoma. The tumor was excised and sent for histopathological examination. Grossly, it was a ovoid solid-cystic firm to hard mass, microscopy showed large areas of dystrophic calcification with cystic spaces surrounded by foreign body giant cell reaction. Correlating with history, clinical findings, biochemical findings, the diagnosis of primary normophosphatemic tumoral calcinosis was made.

Negative nasopharyngeal swabs in COVID-19 pneumonia: the experience of an Italian Emergengy Department (Piacenza) during the first month of the Italian epidemic.

Coronavirus disease (COVID-19) is a systemic disease which can cause multiple organ failure and death primarly due to vascular endothelium injury. Severe acute respiratory distress syndrome (ARDS) is the main cause of death: its management and treatment should be tailored to the individual COVID-19 patient’s phenotype. Early diagnosis of COVID-19 is paramount for disease treatment and infection control. Naso-pharyngeal (NP) swab is commonly used as screening and diagnostic tool for COVID-19, but in some cases it can be resulted negative even in presence of clinical and epidemiological criteria, and typical radiological and laboratory findings of COVID-19, as we have observed. Here we report our experience in the first month of the Italian epidemic. We strongly recommend clinicians to maintain a high index of suspicion for COVID-19, regardless of the persistence negativity of NP swabs, and not to delay the initiation of therapy in presence of typical clinical, radiological and laboratory findings of COVID-19. (www.actabiomedica.it)

Chronic obstructive pulmonary disease and COVID-19

The coronavirus disease 2019 (COVID-19) pandemic tends to have a more severe clinical picture in the elderly and in patients with chronic diseases, one of which is chronic obstructive pulmonary disease (COPD). Around 2%–3% of patients infected with coronavirus have had the diagnosis of COPD; the critical care, intubation requirement, and mortality rate have been higher among this group of patients with the development of hypoxemia. Exacerbation and COVID-19 pneumonia are two differential diagnoses in patients with COPD; the fever among the symptoms, lymphopenia among the laboratory findings, and typical radiological findings in thoracic tomography of patients may be helpful in the diagnosis of COVID-19. The stabilization of the disease is important in the follow-up of patients with COPD during this pandemic; the continuation of maintenance treatment of patients has been accepted as the main strategy. Droplet and contact transmissions should be decreased, and basic hygiene and nutritional rules should be followed in the COPD patient group in which the risk of infection development is high. There are various opinions on the administration of treatment through nebulizers during the pandemic; the use of inhaler devices is the safer and recommended method. Since noninvasive mechanical ventilators may increase the risk of contamination, they are not included among the routine treatment recommendations for patients with COPD.

Acute Presentation of Amiodarone Toxicity with Pleural Involvement

Amiodarone is a frequently prescribed anti-arrhythmic drug which is used to treat ventricular and supraventricular tachyarrhythmia. Although it has excellent efficacy in controlling or preventing common arrhythmias, it is potentially associated with a variety of adverse effects, the most serious of these being pulmonary toxicity. Amiodarone-associated toxicities are usually seen in solid organs like lung, spleen and thyroid due to extension of its pharmacokinetic properties. The presentation is often subacute. Acute presentation with pleural involvement is distinctly uncommon in amiodarone toxicity and can pose diagnostic challenges. Here the case presented is of a 67 year old female with multiple co-morbidities on amiodarone therapy, who presented with massive pleural effusion and respiratory failure. Typical radiological findings along with exclusion of alternate causes with appropriate tests led to a diagnosis of amiodarone toxicity involving lung parenchyma, pleura, liver and other organs. She responded to withdrawal of drug, steroid therapy and supportive care.

Idiopathic Intracranial Hypertension: The Monster Within.

Idiopathic intracranial hypertension (IIH) is defined as a syndrome of raised intracranial pressure with normal imaging of the brain and cerebrospinal fluid (CSF) composition. There are many controversies and myths that surround IIH. Although patients of IIH may present “typical” symptoms and signs of raised intracranial pressure, clinical scenarios often vary. A typical clinical and radiological finding poses significant problems in diagnosis and management of patients with IIH. We have tried to resolve these controversies and provide a comprehensive update on different aspects of IIH. In this article, we review the common problems encountered while dealing with patients of IIH.

Radiology of COVID-19 - Imaging the pulmonary damage.

A large part of the world is presently in the grip of the coronavirus disease (COVID-19) by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 virus), declared a pandemic in March 2020. This document is a brief commentary of the imaging modalities used in the screening, diagnosis and management of COVID-19 pneumonia. Chest x-rays, especially portable, still form a part of majority of official guidelines, with reports of the suggestive radiologic features. The potential of CT scan and ultrasound is also realised, with earlier detection rate. Typical radiologic findings of bilateral, asymmetrical, crazy-paved ground glass opacification, consolidation, reverse halo sign, opacities, progressing to fibrosis are well described for both the X-ray and CT scan. Atypical findings include airway changes, pleural effusion, pulmonary nodules and acute pulmonary embolism. Absence of lymphadenopathy, pleural effusion and pneumothorax is notable. The role of portable lung ultrasound, reported to be useful in emergency, is yet to be established in the guidelines. Disinfection of the equipment is a major concern. Governmental guidelines still advocate X-ray despite professional societies increasingly recommending CT scan.

Pulmonary Alveolar Microlithiasis in Children Less than 5 Years of Age

To collect all published cases up to January 2019 of pulmonary alveolar microlithiasis (PAM) in patients age 5years and under and to compare their characteristics with those of the 1022 cases in the most recent all-age cohort published in2015. We identified 28 cases of PAM worldwide in children age 5years and under, accounting for only 2%-3% of all cases. Children seem more frequently symptomatic, notably with more cough and severe acute respiratory failure, but had no reported extrapulmonary manifestation. Children with PAM evidenced less typical radiologic findings, with frequent ground glass opacities not reported in adult cases and milder calcifications as less frequent, smaller, and mainly restricted to the lower lobes. PAM remains an uncommon diagnosis in young children, as symptoms and radiologic findings are less specific. Physicians should be aware to look for calcifications in chest computed tomography at mediastinal window and avoid elution of the bronchoalveolar lavage to find microliths. Collecting longitudinal data through an international registry would help in characterizing PAM to predict disease progression and plan lung transplantation.

80 Sleeping Beauty

Abstract Background The artery of Percheron is a rare anatomic variant of arterial supply to the paramedian thalamus and rostral midbrain, and occlusion of the artery of Percheron results in bilateral paramedian thalamic infarcts with or without midbrain involvement. Early diagnosis of artery of Percheron infarction can be challenging because it is infrequent and early computed tomography or magnetic resonance imaging may be negative. Thus, it can be confused with other neurological conditions such as tumours and infections. Methods This is a retrospective case study of a gentleman admitted to a teaching Hospital in Limerick and diagnosed with an artery of Percheron infarction. Medical records and the neuro-radiological database were reviewed, and the diagnosis was made based on typical symptoms and radiological findings of artery of Percheron infarction. Results We report the case of a gentleman who was found unconscious in his car on the roadside during the daytime. He had a decreased GCS and upon arrival in the Emergency Department he was intubated and transferred to ITU The initial head computed tomography performed on admission was reported as unremarkable. Bilateral ischemia in the paramedian thalamic nuclei was documented on a follow-up computed tomography on day 24 after hospitalization. He was extubated after 24 hours. He made a full recovery and was discharged home on day 5. Conclusion Artery of Percheron infarcts are rare. The radiological diagnosis can initially often be judged as normal and in combination with variability in the neurological symptoms it is a rather difficult condition to diagnose.

P14.42 Diagnostic challenges of infratentorial hemangioblastomas: improvement of current radiological classification scheme

Abstract BACKGROUND Hemangioblastomas (HBMs) are known to exhibit very typical radiological features and thus classified by well-established radiological classification scheme. However, after we have experienced unusual cases in which current radiological classification system was not enough to categorize them, we reviewed our series of infratentorial HBMs in order not only to evaluate the relevance of current classification scheme, but also to possibly improve it. Also, we added descriptions on several cases with unusual radiological magnetic resonance imaging (MRI) findings in which differential diagnosis was challenging. MATERIAL AND METHODS We retrospectively reviewed preoperative MRI of 118 patients with pathologically diagnosed infratentorial HBMs at our institution between 2002 and 2015. Total 128 tumors were included to this study and classified into four categories based on the presence and nature of cystic components: extratumoral cystic (Type Ce, classical cystic with a mural nodule), intratumoral cystic (Type Ci), mixed cystic (Type Cm), and solid (Type S). The association with von Hippel-Lindau (VHL) disease was also investigated. RESULTS In 118 patients (65 male and 53 female), 79 (66.9%) had solitary HBMs and 39 (33.1%) were diagnosed with VHL disease. Type Ce with typical radiological findings was the most prevalent type of HBM (63.3%), followed by Type S (21.1%). HBMs with intratumoral cysts were uncommon (Type Ci, 11.7%) and mixed extratumoral and intratumoral cysts (Type Cm) accounted for only 3.9%. No intergroup differences were observed in the proportions of each subtype between the solitary and VHL disease-associated HBMs. CONCLUSION Radiological features of HBMs are usually typical thus preoperative presumption is not difficult in majority of cases. Improved radiological classification scheme is more practical because it does not only help surgeons determine whether the cystic wall should be removed or not, but also covers cases with atypical radiological presentations. For solid and extraparenchymal HBMs, differential diagnosis is more difficult as well as very critical as surgical removal is often very challenging.

Psychometric analysis of questions associated with radiological images in the competitive examination for access to residency programs in Spain

Background and objectivePsychometrics is a simple, intuitive approach used in educational research and in multiple-choice questionnaires. Since 2009, the competitive examination through which access to residency programs in Spain is determined (MIR) has included questions related to radiological images. The objective of this paper is to show the results of the psychometric analysis of these questions with the aim of comparing their degree of difficulty, discriminative capacity, and internal structure with respect to those of the other questions on the examination. Material and methodsWe analyzed all questions on the examination since 2009, classifying them as clinical cases with and without radiological images, clinical cases with and without non-radiological images, multiple choice questions, and negative questions. We used classical test theory and item response theory to assess the difficulty and degree of discrimination of the questions. ResultsOf 225 questions, between 11% and 15% of the questions included in the examinations were associated with images. The questions associated with radiological images were more difficult (corrected difficulty index, 0.51) and had worse discriminative capacity. The increased difficulty of radiological questions was associated with worse discriminative capacity, especially if the clinical information provided was inadequate or if the clinical information was contrary to the radiological concept or if there had never been any questions about the concept in previoous MIR examinations. ConclusionsTo equalize the standards of the MIR examination, it is necessary to maintain an appropriate structure in devising radiology questions, with terms from the clinical context, appropriate use of distracters, and a lower level of difficulty, which could be achieved by using radiological images with typical radiological findings.

Safe and Effective Treatment Choice for Osteoid Osteoma: Computed Tomography-guided Percutaneous Radiofrequency Ablation.

IntroductionOsteoid osteoma (OO) is a painful, benign, bone-forming tumor characterized by a small central nidus surrounded by sclerotic tissue. The aim of the present study was to evaluate the clinical outcome after computed tomography (CT)-guided radiofrequency ablation (RFA) in patients with OO performed from January 2012 to June 2018 and to confirm the safety and efficacy of CT-guided RFA.MethodsBetween January 2012 and June 2018, a total of 63 patients were treated with CT-guided RFA. Pre- and post-treatment pain, further treatment after the RFA procedure, observed complications, and satisfaction with the treatment were recorded for an assessment of clinical effects in all patients. The patients were evaluated with the visual analog scale (VAS) pre-procedure and at three months post-procedure.ResultsOf the patients, 39 were males and 24 were females with a mean age of 21 ± 9.7 (range, 9 to 41) years. The mean follow-up was 16 ± 2.1 (range, 12 to 19) months. The mean duration of the procedure was 34 ± 11.4 (range, 22 to 47) min. All of the patients were diagnosed with OO pathologically. A statistically significant difference was found between the pre-procedural and post-procedural VAS scores (p<0.001). Complications were observed in six patients including one peroneal nerve lesion, three minor skin burns, and two minor skin infections.ConclusionThis study shows that CT-guided RFA is a safe and effective treatment for OO. It is thought that RFA could be the primary treatment choice for most OO with typical symptoms and radiological findings.

The capability of chest computed tomography in the diagnosis of bronchopulmonary dysplasia outcomes in premature infants

Purpose of the study was to establish clinical and radiological features of bronchopulmonary dysplasia (BPD) outcomes in children. Materials and methods. A prospective follow-up study of 132 premature infants with infant respiratory distress syndrome (IRDS) was analyzed. BPD was developed in 66 cases. At a late childhood, clinical and radiological outcomes of the transferred conditions were diagnosed on the basis of anamnesis, clinical examination, and results of chest computed tomography (CT). Results. Clinical recovery was observed significantly more frequently in the outcome of IRDS without BPD development (69.6% versus 31.8% in the case of BPD development). In patients with BPD in the anamnesis, the odds ratio of asthma developed in the late childhood was 5.304 times higher than in children who had IRDS. The majority (62 cases, 93.9%) of children who had IRDS did not have structural changes in lung tissue according to CT (p = 0.000), 21 (31.8%) children with BPD had abnormal CT. In BPD, typical radiological findings were hypoattenuated lung areas (p = 0.020) and areas of pulmonary fibrosis (p = 0.016). Conclusion. Chest CT could be assigned to the patients with BPD in the anamnesis to assess lung tissue structural changes and diagnose outcomes of the disease.

Percutaneous radiofrequency ablation of adrenal metastases from hepatocellular carcinoma: a single-center experience

BackgroundThe prognosis of adrenal metastases (AM) from hepatocellular carcinoma (HCC) with surgical contraindication was poor. This study evaluated the feasibility, safety and treatment efficacy of percutaneous ultrasound (US)-guided radiofrequency ablation (RFA) for the local treatment of AM originated from HCC.MethodsA retrospective study was carried out on 22 patients (21 male and 1 female, mean age, 53.0 ± 13.0 years) who had single AM (mean diameter, 4.0 ± 1.8 cm, range, 1.7–8.0 cm) originated from HCC and received US-guided percutaneous RFA at our institution. The diagnosis was established on typical radiologic findings. The primary technical success was defined as the tumour being completely ablated in the first RFA session. The secondary technical success was defined as tumour residual left from the first ablation was completely ablated by a second ablation session. Local tumour progression (LTP) and overall survival (OS) were estimated by using Kaplan-Meier analysis.ResultsA total of 25 ablation sessions were performed. The primary technical success and the secondary technical success were 77.3% (17 of 22) and 86.4% (19 of 22), respectively, with the major complication rate at 4.5% (1 of 22). The median follow-up period after RFA was 10 months (3–55 months). During the follow-up period, five patients were detected LTP. The LTP at 3, 6, and 12 months were 15.8, 26.3, and 26.3%, respectively. Nine patients died of distant extra-adrenal metastases and another five of liver failure due to HCC. The OS at 6, 12, 24 months after RFA for AM were at 79.7, 52.6, and 32.9%, respectively.ConclusionPercutaneous US-guided RFA in the treatment of AM originated from HCC is feasible, safe and effective.

Análisis psicométrico de las preguntas asociadas a imágenes radiológicas en el examen para médico interno residente en España

Background and objectivePsychometrics is a simple, intuitive approach used in educational research and in multiple-choice questionnaires. Since 2009, the competitive examination through which access to residency programs in Spain is determined (MIR) has included questions related to radiological images. The objective of this paper is to show the results of the psychometric analysis of these questions with the aim of comparing their degree of difficulty, discriminative capacity, and internal structure with respect to those of the other questions on the examination. Material and methodsWe analyzed all questions on the examination since 2009, classifying them as clinical cases with and without radiological images, clinical cases with and without non-radiological images, multiple choice questions, and negative questions. We used classical test theory and item response theory to assess the difficulty and degree of discrimination of the questions. ResultsOf 225 questions, between 11% and 15% of the questions included in the examinations were associated with images. The questions associated with radiological images were more difficult (corrected difficulty index, 0.51) and had worse discriminative capacity. The increased difficulty of radiological questions was associated with worse discriminative capacity, especially if the clinical information provided was inadequate or if the clinical information was contrary to the radiological concept or if there had never been any questions about the concept in previoous MIR examinations. ConclusionsTo equalize the standards of the MIR examination, it is necessary to maintain an appropriate structure in devising radiology questions, with terms from the clinical context, appropriate use of distracters, and a lower level of difficulty, which could be achieved by using radiological images with typical radiological findings.

A patient with Korsakoff syndrome of psychiatric and alcoholic etiology presenting as DSM-5 mild neurocognitive disorder.

Background: Wernicke’s encephalopathy (WE) and Korsakoff syndrome (KS) are underdiagnosed. The DSM-5 has raised the diagnostic threshold by including KS in the major neurocognitive disorders, which requires that the patient needs help in everyday activities.Methods: We report clinical, neuropsychological, and radiological findings from a patient who developed Wernicke-Korsakoff syndrome as a result of alcohol use and weight loss due to major depression. We assess the diagnosis in the context of the scientific literature on KS and according to the DSM-IV and the DSM-5.Results: The patient developed ataxia during a period of weight loss, thus fulfilling current diagnostic criteria of WE. WE was not diagnosed, but the patient partially improved after parenteral thiamine treatment. However, memory problems became evident, and KS was considered. In neuropsychological examination, the Logical Memory test and the Word List test were abnormal, but the Verbal Pair Associates test was normal (Wechsler Memory Scale-III). There were intrusions in the memory testing. The Wisconsin Card Sorting Test was broadly impaired, but the other test of executive functions (difference between Trail Making B and Trail Making A tests) was normal. There was atrophy of the mammillary bodies, the thalamus, the cerebellum, and in the basal ganglia but not in the frontal lobes. Diffusion tensor imaging showed damage in several tracts, including the uncinate fasciculi, the cinguli, the fornix, and the corona radiata. The patient remained independent in everyday activities. The patient can be diagnosed with KS according to the DSM-IV. According to the DSM-5, the patient has major neurocognitive disorders.Conclusions: Extensive memory testing is essential in the assessment of KS. Patients with a history of WE and typical clinical, neuropsychological, and radiological KS findings may be independent in everyday activities. Strict use of the DSM-5 may worsen the problem of Wernicke-Korsakoff syndrome underdiagnosis by excluding clear KS cases that do not have very severe functional impairment.

The zygomatic fracture – Typical clinical and radiological findings

Fractures of the midface involve anatomical structures and skull openings such as the piriform aperture (Le Fort I), the infraorbital foramen (Le Fort II) or the zygomatic bone (Le Fort III). Lateral midface fractures are among the most common injuries to the facial skull and usually affect the zygomaticoorbital complex.

Ischemic complications after percutaneous radiofrequency ablation of liver tumors: Liver volume loss and recovery.

The liver regrows after acute liver injury and liver resection. However, it is not clear whether the liver regenerates in advanced cirrhosis. This study aimed to evaluate the clinical course of, and liver volume change after, ischemic liver complications caused by radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC). We enrolled 35 patients with ischemic complications after RFA. Ischemic complications were defined as rapid elevation of aspartate aminotransferase (AST) to over 500U/L, with typical radiological findings. Patient characteristics and the ischemic liver volume were investigated. Long-term liver volume changes at 3-8months after ischemic complications were also assessed in 32 patients. We also assessed the overall survival rate after ischemic complications. The median value of peak AST was 798U/L (range, 531-4096U/L). The median ischemic liver volume relative to the functional liver volume before RFA was 13% (range, 3.1-46.5%). There was a strong correlation between the peak AST value and the ischemic liver volume (r = 0.84, P < 0.001). The liver volume recovered to some extent in 18 of 32 (56%) patients after ischemic complications. The survival rate after ischemic complications was 45.7% at 5years and correlated with the functional liver volume after ischemic complications (P = 0.02). Ischemic complications after RFA can lead to massive liver parenchymal loss. Although the liver volume recovered to some extent in the majority of our patients, ischemic liver complications after RFA should be avoided to improve the overall survival rate.

Clinical and radiological findings in Brazilian patients with mucolipidosis types II/III.

The present study aims to provide orientation for clinicians and radiologists to recognize the most prevalent findings leading to diagnosis in mucolipidosis from a description of the natural history of five Brazilian cases. We conducted an observational and retrospective study of five patients with clinical and radiological diagnosis of mucolipidosis. Clinical evaluation consisted of information obtained from records and including physical, neurologic, and dysmorphic evaluations. Radiologic studies consisted of complete skeletal radiographs of all patients. Enzyme assessment was performed for confirmation of the diagnosis. The five patients were referred for genetic evaluation due to disproportionate short stature with short trunk accompanied by waddling gait. Age at referral varied from 11months to 28years. The most prevalent findings were joint restriction (4/5 patients), neuropsychomotor developmental delay (3/5), coarse facies (2/5), hypertrophic cardiomyopathy (2/5), and mental retardation (1/4 patients). The most common radiological findings were anterior beaking of the vertebral bodies (5/5), shallow acetabular fossae (5/5), epiphyseal dysplasia (5/5), platyspondyly (4/5), pelvic dysplasia (4/5), decreased bone mineralization (4/5), scoliosis (3/5), wide and oar-shaped ribs (3/5), generalized epiphyseal ossification delay (3/5), and hypoplasia of basilar portions of ilea (3/5). Enzyme assessment showed α-iduronidase, α-mannosidase, β-glucuronidase, hexosaminidase A, and total hexosaminidase increased in plasma and normal glycosaminoglycans concentration. One patient was clinically classified as ML II and four patients as ML III. The follow-up of five patients showed the typical clinical and radiological findings allowing the diagnosis, thus improving clinical management and providing adequate genetic counseling. Clinicians and radiologists can take advantage of the information from this work, enhancing their differential diagnosis ability.

Clinical, Radiological, and Demographic Details of Benign External Hydrocephalus: A Population-Based Study

BackgroundBenign external hydrocephalus has an incidence of about 0.4 per 1000 live births. It affects infants and is characterized by an increasing head circumference and typical neuroimaging findings. Previously published studies on benign external hydrocephalus often contain groups of few and selected patients. MethodsThis is a follow-up of a recently published article reporting the incidence of benign external hydrocephalus. This retrospective and population-based study covers two large health regions in Norway, over a 10-year period (1994 to 2003). Infants with increasing head circumference, combined with typical radiological findings of enlarged subarachnoid spaces, were included. Information about head circumference development, neuroimaging findings, and birth delivery methods, as well as demographic details, was retrieved from the hospital medical records. ResultsA total of 176 children with benign external hydrocephalus were included, 86.4% being boys. At birth, the head circumference was close to normal. Mean age for when the head circumference reached abnormal values, i.e., crossing two percentiles or reaching the 97.5 percentile, was 3.4 months; none was older than seven months. Around four of five children had dilated lateral ventricles in addition to enlarged subarachnoid spaces. The neuroimaging findings tended to normalize after age 12 months. About half of the patients ended up with head circumferences at or above the 97.5 percentile. ConclusionsMost infants with benign external hydrocephalus are born with a normal head circumference that increases too fast and reaches abnormally high values before age six months. This age and gender distribution is very similar to that described for infant subdural hemorrhage.