SUBMITTED 11 FEB 23 1 REVISION REQ. 2 APR 23; REVISION RECD. 8 APR 23 2 ACCEPTED 19 APR 23 3 ONLINE-FIRST: MAY 2023 4 DOI: https://doi.org/10.18295/squmj.5.2023.024 5 6 Absent Septum Pellucidum 7 Search for other anomalies 8 Khadija Saleh,1 Eiman Al-Ajmi,2 *Amna Al Futaisi3 9 10 1Pediatrics Program, Oman Medical Specialty Board, Muscat, Oman; 2Department of 11 Radiology and Molecular Imaging, Sultan Qaboos University Hospital, Sultan Qaboos 12 University, Muscat, Oman; 3Department of Paediatrics, College of Medicine and Health 13 Sciences, Sultan Qaboos University, Muscat, Oman 14 *Corresponding Author’s e-mail: amnaf@squ.edu.om 15 16 Introduction 17 A 6-week-old infant was referred to the paediatric neurology unit of a tertiary care hospital, 18 in 2019 from a peripheral hospital for further evaluation. This referral was prompted by an 19 antenatal scan that revealed an absent cavum septum pellucidum and a postnatal head 20 ultrasound that suggested septo-optic dysplasia. Despite these findings, the infant appeared to 21 be developing normally with normal muscle tone, strength and sucking reflex. The infant was 22 born at full term via spontaneous vaginal delivery with a birth weight of 3 kg, head 23 circumference of 34 cm, length of 52 cm and a good Apgar score; he had also received all the 24 vaccinations recommended at birth. There was no history of maternal infection during 25 pregnancy, medication intake, smoking or substance abuse. His parents were 26 consanguineous, but there was no family history of genetic or neurological disorders. 27 28 An ophthalmologist examined the patient and found no optic nerve atrophy or other ocular 29 abnormalities. Magnetic resonance imaging (MRI) of the brain at the age of thirty-three 30 months revealed an isolated absence of the septum pellucidum (ASP) but no signs of septo-31 optic dysplasia, optic nerve hypoplasia or visible pituitary abnormalities (Figure 1). 32 Furthermore, an endocrinological evaluation revealed no endocrine abnormalities. The 33 mailto:amnaf@squ.edu.om patient, who is currently 3 years old, is healthy with no obvious physical abnormalities and 34 shows age-appropriate development; thus, was diagnosed with isolated ASP. 35 36 Informed consent was obtained from the parents for the publication of the images. 37 38 Comment 39 ASP is a rare developmental brain anomaly that can be partial or complete. It is often 40 associated with congenital brain defects, such as holoprosencephaly, septo-optic dysplasia, 41 schizencephaly and corpus callosum agenesis. Isolated ASP should be suspected in infants 42 with normal findings on neurological examination but with an absent cavum septum 43 pellucidum on antenatal scans.1 It is challenging to differentiate between isolated ASP and 44 septo-optic dysplasia in utero using current imaging techniques because it can be difficult to 45 rule out the possibility of optic nerve hypoplasia and endocrine abnormalities.2 Prenatal 46 ultrasonography can detect cavum septum pellucidum between 18 and 37 weeks of gestation, 47 or with a biparietal diameter of 44-88mm.The mean width of the cavum septum pellucidum is 48 5.3 +/- 1.7 mm with a range of 2 to 9 mm.3 If the cavum septum pellucidum is not detected on 49 antenatal scanning during this period, it may indicate abnormal brain development and 50 necessitate further examination.4 51 52 Isolated ASP is uncommon, occurring in approximately 0.2–0.3 of every 10,000 people. 53 However, the true incidence might be higher due to limitations in sonography such as skills 54 of the operator, restricted field of view and visualization.5 The prognosis of this condition is 55 presently unknown, but it has been associated with undetectable pathological changes on 56 ultrasound or MRI.4 57 Few cases of isolated septal agenesis have been associated with schizophrenia as it is 58 considered part of the limbic system.4 Other cases have been associated with speech delays or 59 behavioural problems.4 In a retrospective cohort study, antenatal genetic tests were performed 60 in 30 foetuses with suspected isolated ASP, 2 of which had an abnormal result.6 The majority 61 of cases with a prenatal isolated ASP diagnosis have a favourable prognosis.6 However, if 62 other anomalies are detected, the clinical outcome is worse.6 Screening for associated 63 anomalies is mandatory for new-borns who are identified with ASP on antenatal ultrasound. 64 An early understanding of whether ASP is an isolated anomaly or part of a syndrome enables 65 the clinicians to provide appropriate counselling for families and to establish early 66 rehabilitation and guidance for future management of such patients. 67 68 Authors’ Contribution 69 KS did the initial writing of the manuscript. EA prepared the images and description and 70 revised and edited the manuscript. AF was responsible for the idea of the manuscript as well 71 as the revision and editing at all stages. All authors approved the final version of the 72 manuscript. 73 74 References 75 1. Ben M'Barek I, Tassin M, Guët A, Simon I, Mairovitz V, Mandelbrot L, et al. 76 Antenatal diagnosis of absence of septum pellucidum. Clin Case Rep. 2020 Feb 77 5;8(3):498-503. https://doi.org/10.1002/ccr3.2666 78 2. García-Arreza A, García-Díaz L, Fajardo M, Carreto P, Antiñolo G. Isolated absence 79 of septum pellucidum: prenatal diagnosis and outcome. Fetal Diagn Ther. 80 2013;33(2):130-132. https://doi.org/10.1159/000338009 81 3. Falco P, Gabrielli S, Visentin A, Perolo A, Pilu G, Bovicelli L. Transabdominal 82 sonography of the cavum septum pellucidum in normal fetuses in the second and third 83 trimesters of pregnancy. Ultrasound Obstet Gynecol. 2000;16(6):549-553. 84 https://doi.org/10.1046/j.1469-0705.2000.00244.x 85 4. Pilu G, Tani G, Carletti A, Malaigia S, Ghi T, Rizzo N. Difficult early sonographic 86 diagnosis of absence of the fetal septum pellucidum. Ultrasound Obstet Gynecol. 87 2005;25(1):70-72. https://doi.org/10.1002/uog.1786 88 5. Hosseinzadeh K, Luo J, Borhani A, Hill L. Non-visualisation of cavum septi 89 pellucidi: implication in prenatal diagnosis?. Insights Imaging. 2013;4(3):357-367. 90 https://doi.org/10.1007/s13244-013-0244-x 91 6. Di Pasquo, E., Kuleva, M., Arthuis, C., Morganelli, G., Ormitti, F., Millischer, A. E., 92 et al. Prenatal diagnosis and outcome of fetuses with isolated agenesis of septum 93 pellucidum: cohort study and meta-analysis. Ultrasound Obstet Gynecol. 94 2022;59(2):153-161. https://doi.org/10.1002/uog.23759 95 96 97 https://doi.org/10.1002/ccr3.2666 https://doi.org/10.1159/000338009 https://doi.org/10.1046/j.1469-0705.2000.00244.x https://doi.org/10.1002/uog.1786 https://doi.org/10.1007/s13244-013-0244-x https://doi.org/10.1002/uog.23759 98 Figure 1. Magnetic resonance imaging of the brain done for the patient at age of thirty-three 99 months shows absence of the septum pellucidum in an axial T2-weighted image (A). (B) 100 Coronal T2-weighted image showing squaring of the frontal horns with inferior pointing 101 (dashed arrows). The pre-chiasmatic segments of the optic nerves are bilaterally visible with 102 normal size (arrows). (C) An axial T2-weighted image from another patient shows normal 103 septum pellucidum (black arrow). 104