CASE 13413 Published on 08.03.2016

Isolated Agenesis of Septum Pellucidum

Section

Neuroradiology

Case Type

Clinical Cases

Authors

1,2Laila Adel Mohsen, 3Ahmed A. Mohsen, 1Adel M. Samy

1Radiology Department, Minia University Hospital, Minia, Egypt, 2Radiology Department, Thumbay Hospital, Dubai, UAE, 3Radiology Department, Minia Oncology Center, Minia, Egypt; Email:dr.laila.adel77@gmail.com
Patient

33 years, female

Categories
Area of Interest Neuroradiology brain, Abdominal wall ; Imaging Technique MR, CAD
Clinical History
A 33-year old lady and mother of 2 healthy children, complained of frequently occurring headaches. Her physical examination and vital signs were normal. Her laboratory results were normal. She had no visual disturbances and her ENT examination was normal. She had no behavioural or psychological disorders.
Imaging Findings
MRI of the brain was requested for screening purposes to exclude any intra-cranial pathologies. MRI revealed absence of the septum pellucidum with the bodies of both lateral ventricles seen communicating across the midline. The fornix was at a lower position, due to the loss of tethering effect of the septum pellucidum, but was otherwise normal. The corpus callosum, optic chiasm and nerves were normal. The rest of the brain tissue and posterior fossa were normal. She had no intra-cranial mass lesions or other pathology that would explain her headaches.
Discussion
Midline anomalies of the brain are a common spectrum of anomalies and many of them are usually associated. Isolated septal agenesis was initially considered an associated anomaly to other more common midline cerebral anomalies. But now several authors agree that it can occur at an extremely rare incidence and has better prognosis than other anomalies [1]. It was estimated to be 2-3 per 100,000. More recent studies suggested that this is an underestimated rate and the incidence was reported to be 1:1000 to 1:3000 [2].
Some patients with isolated septal agenesis were reported to develop language developmental delay, while others develop behavioural changes. However, until now, there is no strong evidence for the association of isolated septal agenesis with developmental delay or behavioural changes. This could be due to the extremely low incidence of the anomaly.
By imaging, the main findings that denote isolated septal agenesis is the non visualization of the septum pellucidum and fusion of parts of both lateral ventricles without any fusion between both cerebral hemispheres. Corpus callosum and optic chiasm and nerves are normal. The fornix is seen at a lower level, due to the loss of the tethering effect of the septum pellucidum, but otherwise, it is within normal limits.
Several authors are suspecting that there could be some associated cyto-architectural changes that are not yet detectable by MRI. This suggestion is attributed to some observations. First, septum pellucidum constitutes part of the limbic system, which is implicated in the pathogenesis of schizophrenia and many patients with psychosis and schizophrenia have associated septal anomalies. Similarly, many patients who develop epileptic seizures, also show evidence of septal anomalies [3-5]. Thus, children with isolated septal agenesis should be followed up regularly for their cognitive and behavioural development.
The main differential diagnoses for these findings are the holo-prosencephaly (HPE), septo-optic dysplasia (SOD) and agenesis of corpus callosum (ACC). In HPE, there are variable degrees of fusion of both cerebral hemispheres. In SOD, there is unilateral or more commonly bilateral optic nerve hypoplasia. In ACC, the corpus callosum is absent entirely or predominantly in its splenial component. Isolated septal agenesis is a very rare anomaly. More common cerebral midline anomalies should be thoroughly investigated before confirming this diagnosis.
Differential Diagnosis List
This patient was diagnosed as having isolated agenesis of the septum pellucidum.
Holo-prosencephaly.
Septo-optic dysplasia.
Agenesis of Corpus Callosum.
Final Diagnosis
This patient was diagnosed as having isolated agenesis of the septum pellucidum.
Case information
URL: https://www.eurorad.org/case/13413
DOI: 10.1594/EURORAD/CASE.13413
ISSN: 1563-4086
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