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Aims and Objectives: It is impossible to precisely anticipate the course of the transverse and sigmoid sinuses and theirindividual relationship to superficial landmarks such as the asterion during retrosigmoid approaches. This study was done todetermine the position of the asterion and the relationship between asterion and the transverse-sigmoid sinus junction (TSSJ)in making precise burr hole without damaging sinuses during retrosigmoid craniotomies.Materials and Methods: Computed tomography (CT) angiography was performed in 50 patients to obtain 3D-CT volumerendering images of cranial bone and dural sinuses. After delineating the sinuses, by simple restructuring using software andopacity modulation, bone image is reinforced. Asterion type, distance from the tip of mastoid process to asterion and root ofzygoma (ROZ) to asterion, and location of asterion in relation to TSSJ and distance between asterion and TSSJ were analyzedand measured.Results: The incidence of type 1 (presence of sutural bones) in our study was 24% and type 2 (absence of sutural bones) was76%. There was no statistically significance in the side and gender differences. The distance between the asterion and fromthe ROZ was 54.70 ± 3.68 on the right side and 54.32 ± 3.41 on the left side (P-0.612). The distance between asterion and tipof mastoid was 50.51 ± 2.67 on the right side and 50.12 ± 3.06 on the left side (P-0.716). The asterion was located on the T-Ssinus complex in 36 (72%) cases. The asterion was below the T-S sinus complex in 13 (26%) cases, and above the T-S sinuscomplex in only 1 (2%) cases.Conclusion: 3D-CT volume rendering imaging is capable of accurately visualizing the bony landmark and dural sinuses. Aneasy and simple restructured image provides precision and safety for the patient by ready and easy localization of asterionand TSSJ. This study was done to show that the previous cadaver-based anatomical studies can be done now in a moresophisticated and accurate manner with the latest technological advancements. This offers new options for anatomic researchand morphometric investigations.
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Introduction: Colloid cysts are one of the benign intracranial tumors most commonly occurring in the rostral part of the thirdventricle. These may present with varied spectrum of clinical features that poses challenges in clinical diagnosis. The presentationmay range from being asymptomatic to simple headaches, seizures, and even sudden death. Most of the symptoms can beattributed to the development of obstructive hydrocephalus. Chemical or aseptic meningitis is unusual complication posingcomplicating differential diagnosis. We describe eight such cases with wide variety of symptoms.Materials and Methods: We present a case series of eight cases of the third ventricle colloid cysts presented at our institute.Age of the patients ranged from 15 to 55 and five of them were females. All the clinical features were recorded from eachone of them. Computed tomography and magnetic resonance imaging were used to diagnose the condition. Four of themunderwent excision of the cyst in single stage either by open or endoscopic approach. Two patients underwent preliminaryventriculoperitoneal shunt done in the view of poor neurological status and craniotomy and excision was done in later stage. Inone patient bedside external ventricular drain was inserted for emergency decompression of ventricles. One patient is underserial radiological follow-up.Results: Eight cases that we observed had wide variety of symptoms. Six patients had chronic headache with progressiveseverity, and four of them had nausea with vomiting, three patients had seizures. The cysts in two patients were discoveredaccidentally, during the evaluation of seizures in one patient and others in evaluation of traumatic head injury. One elderly patienthad presented with psychiatric symptoms, drop attacks along with the features of normal pressure hydrocephalus. One teenagepatient presented with sudden deterioration and went into cardiac arrest even after emergency decompression of ventriclesdone. Seven of them underwent surgery and one of them succumbed. The surgery improved health in all other seven patients.Conclusion: Colloid cysts may present with a wide range and beyond expected neurological manifestations. The severity orrapid clinical deterioration does not exactly correlate with depending on the site, size of the cyst. Leaking cysts with chemicalmeningitis may further complicate the diagnosis. Hence, early diagnosis and surgery with complete removal of cysts offer betterclinical outcomes in those patients.