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|Year : 2014 | Volume
| Issue : 6 | Page : 665-668
Operative nuances of excision of colloid cysts in septum pellucidum: A report of three cases
Nishanth Sadashiva1, Savitr Sastry2, Dhananjaya Bhat1, Paritosh Pandey1
1 Department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
2 Department of Neurosurgery, Yashoda Hospitals, Secunderabad, Telangana, India
|Date of Submission||16-Nov-2014|
|Date of Decision||04-Dec-2014|
|Date of Acceptance||20-Dec-2014|
|Date of Web Publication||16-Jan-2015|
Department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bangalore - 560 029, Karnataka
Source of Support: None, Conflict of Interest: None
Colloid cysts are common cysts are often located in the anterior third ventricle and septum pellucidum location is extremely rare. Cysts in septum pellucidum can be missed at surgery because of their unusual location. We describe three patients with colloid cysts in the septum pellucidum, with two in the cavum septum pellucidum. Various surgical implications of this unusual location are enumerated.
Keywords: Colloid cyst, septum pellucidum, transcallosal
|How to cite this article:|
Sadashiva N, Sastry S, Bhat D, Pandey P. Operative nuances of excision of colloid cysts in septum pellucidum: A report of three cases. Neurol India 2014;62:665-8
| » Introduction|| |
Colloid cysts (CC) are benign lesions, accounting for 0.5-1% of intracranial lesions. Embryologically, they arise from invagination of mesodermal tissues into the neuroepithelium. The majority are located in the roof of third ventricle in relation to the foramen of Monro (FoM), presenting with symptoms suggestive of cerebrospinal fluid (CSF) pathway blockage, either intermittent or acute.  However, other locations of CC have been described in literature, of which the septum pellucidum is relatively rare. We describe three patients with CC in septum pellucidum, including two cases in cavum septum pellucidum (CSP) and the surgical implications.
| » Case Reports|| |
A 27-year-old lady presented with headache of 4-years duration with two episodes of unconsciousness. Neurological examination was normal and magnetic resonance imaging (MRI) of the brain revealed CC located inside a CSP [Figure 1]a-c, inferior part of the cyst reaching FoM. She underwent right frontal parasagittal craniotomy. Through transcallosal transventricular approach, FoM was initially examined but the lesion was not seen, and the foramen was not dilated. Subsequently, CSP was opened and cyst was located entirely within the CSP superior to third ventricle roof. The cyst wall was completely excised. Patient made uneventful recovery and 3 months following surgery, she was asymptomatic, with no neurological deficit. Repeat MRI showed complete excision of cyst and no hydrocephalus [Figure 1]d-f.
|Figure 1: (a) Axial, (b) coronal, and (c) saggital T2 - weighted magnetic resonance imaging (MRI) images showing colloid cyst in cavum septum pellucidum. (d) Axial, (e) coronal, (f) saggital images showing post - operative MRI with complete excision of the lesion|
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A 27-year-old male with intermittent headache and vomiting for 1 month was diagnosed with CC at another hospital. He had undergone right frontal parasaggital craniotomy with transcallosal trans-ventricular approach to reach FoM, but the lesion was not found. The procedure was abandoned and he was referred to our institute. Careful examination of a repeat MRI revealed the cyst in CSP, superior to the FoM [Figure 2]a-d. Re-exploration showed a bulge on the septum which was opened to identify the cyst entirely located inside CSP, superior to roof of third ventricle. It was completely excised. He made an uneventful recovery and post op MRI after 3 months showed complete excision [Figure 2]e-h.
|Figure 2: (a) Axial, (b) coronal T2 - weighted images, (c) axial T2 flair image, (d) saggital T1 contrast magnetic resonance imaging (MRI) showing colloid cyst located inside the cavum septum pellucidum. (e) Axial (f) coronal T2 - weighted images, (g) axial T2 flair image, (H) saggital T1 contrast MRI showing complete excision of the colloid cyst post-operatively|
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A 43-year-old lady presented with intermittent headache and episodes of blackouts. Neurological examination was normal. MRI revealed a small lesion at the region superior to FoM [Figure 3]. She underwent right frontal parasagittal craniotomy, interhemispheric transcallosal approach but as in the two cases above, there was no cyst near FoM. A noticeable bulge in septum pellucidum was incised to find the lesion completely encased in the septum, superior to roof of third ventricle. Complete excision was done and confirmed by CT [Figure 3], and she made an uneventful recovery.
|Figure 3: (a) T2-weighted coronal, (b) coronal CISS 3D, (c) axial T2-weighted flair and (d) axial T2-weighted, (e) T2-weighed saggital, (f) T1-weighed saggital magnetic resonance imaging (MRI) images showing a colloid cyst located in the lower septum pellucidum. (g) Preoperative computed tomography (CT) and (h) post-operative CT showing complete excision of colloid cyst|
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| » Discussion|| |
CC occur predominantly in midline with majority involving roof of third ventricle.  The pathogenesis of CC outside third ventricle has been described in several ways. Ciric emphasized invagination or evagination of neuroepithelium from the diencephalic roof into the interforniceal space, resulting in cyst formation postulated to explain lesions within the third ventricle or up in the septum pellucidum. 
Both microsurgery and endoscopic surgery have been described for CC. Approaches for CC are directed toward the FoM, and the first step after reaching the lateral ventricle is to follow the choroid plexus to the foramen. Surgical implications of cysts located within the septum pellucidum, if not identified preoperatively, are negative exploration and unnecessary dissection around the foramen, which has vital structures around it. This is exemplified in the second patient, where the cyst could not be found, and he had to be re-operated. Prior identification of the cyst at a more superior location in septum will prevent these problems. If no cyst is found, it may be prudent to open the septum pellucidum to look for the cyst. For endoscopic surgery, it is even more important to identify the location, because of the narrow corridor and limited visualization.
CC have been reported in lateral ventricle, fourth ventricle, frontal lobe, parietal lobe, cerebellum, optic nerve, brain stem, and craniovertebral junction.  However, CC in septum pellucidum is rare, reported in only three previous publications [Table 1]. ,, This is the largest report of CC in septum pellucidum, detailing the radiology and nuances of surgery for CC in this location.
|Table 1: Showing previously reported cases of colloid cysts in septum pellucidum|
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| » Conclusion|| |
CSP is an uncommon location for CC. It is important to recognize the location of the cyst preoperatively to avoid negative exploration. If not found near FoM during surgery, the septum pellucidum may be harboring it.
| » References|| |
Desai KI, Nadkarni TD, Muzumdar DP, Goel AH. Surgical management of colloid cyst of the third ventricle--a study of 105 cases. Surg Neurol 2002;57:295-302.
Ciric I, Zivin I. Neuroepithelial (colloid) cysts of the septum pellucidum. J Neurosurg 1975;43:69-73.
Hamlat A, Casallo-Quiliano C, Saikali S, Adn M, Brassier G. Huge colloid cyst: Case report and review of unusual forms. Acta Neurochir (Wien) 2004;146:397-401.
Jeffree RL, Besser M. Colloid cyst of the third ventricle: A clinical review of 39 cases. J Clin Neurosci 2001;8:328-31.
Koc K. Colloid cyst in cavum septum pellucidi: Rare location and endoscopic removal. J Neurol Sci (Turkish) 2007;24:4.
[Figure 1], [Figure 2], [Figure 3]