Variations of Tentorial Notch Anatomy in Autopsy and NCCT of Head Injury Patients to Correlate Its Impact over Brainstem—An Observational Study

Abstract

Background Tentorium cerebelli divide cranial cavity into supratentorial and infratentorial compartment. Tentorial notch is a gap in tentorium cerebelli located centrally and anteriorly, related to upper brainstem, first six cranial nerves, cerebrum, and cerebellum. The aim of this study was to analyze morphometric variation in tentorial notch anatomy in autopsy and computed tomography (CT) of head injury patients and to find out correlation between tentorial notch anatomy and uncal herniation and changes over brainstem surface in case of uncal herniation.

Materials and Methods Autopsy examination of head injury patients was done between July 1, 2021, and Jan 31, 2023. Skull was opened in a standard manner and midbrain sectioned at the level of tentorial edge. Tentorial notch parameters (anterior notch width, maximum notch width, notch length, posterior tentorial length, apicotectal distance, interpedunculoclival distance) were measured using geometry compass and vernier caliper. These parameters were also measured on noncontrast computed tomography (NCCT) head of same patients. Evidence of uncal herniation was sought for in both NCCT head and autopsy examination. Impact of uncal herniation over brainstem in form of indentation over lateral surface of midbrain and macroscopic brainstem hemorrhage was noted.

Results In 65 autopsy cases, there were 56 male and 9 female specimens; their mean age was 40.63 ± 16.78 years (range: 7–86 years). The most frequent type of tentorial notch observed in our study was typical type (32.30%). Relative frequency of uncal herniation was present predominantly (75%) in large type of tentorial notch and least (20%) in small type of tentorial notch. A significant correlation (p-value < 0.01) was found between uncal herniation and indentation over lateral surface of midbrain, while no significant correlation (p-value > 0.05) was found between uncal herniation and macroscopic brainstem hemorrhage in autopsy specimens.

Conclusion The results of our study provide a baseline data about tentorial notch anatomy and it may facilitate neurosurgical decision making as well as help in deciding the best trajectory for lesions approaching in the vicinity of the tentorial notch

Keywords

neuroimaging - postmortem examination - tentorial notch classification - traumatic brain injury - uncal herniation

Note

This paper was presented at the Neurotrauma conference held in Jaipur, Rajasthan, Delhi, India, in 2023.

Publikationsverlauf

Artikel online veröffentlicht:
04. Juni 2024

• References

• 1 Standring S. Intracranial region. In: Standring S. eds. Gray's Anatomy. The Anatomical Basis of Clinical practice. 40th ed.. Elsevier Churchill Livingstone; 2008: 423-34
• 2 Das A, Chhabra S, Das S, Rai P, Saini N. The tentorial notch: morphometric analysis and its clinical relevance to neurosurgery. J Clin Diagn Res 2021; 15 (02) AC10-AC15
• 3 Kunjithapatham D, Pachiyappan JT, Fernand MS. A study to analyze the tentorial incisura in Indian population, for racial differences and its impact in the outcome of patients with head injury. Indian J Neurosurg 2018; 7 (02) 122-128
• 4 Meyer A. Herniation of the brain. Arch Neurol Psychiatry 1920; 4: 387-400
• 5 Sunderland S. The tentorial notch and complications produced by herniations of the brain through that aperture. Br J Surg 1958; 45 (193) 422-438
• 6 Rajaraajan K, Pragadhees R, Prabu SSS, Pradeep S. Morphometric analysis of tentorial incisura and its clinical implications. Int J Sci Stud 2017; 5 (07) 98-104
• 7 Srisaravanan J. Anatomical variation of tentorial hiatus in Indian population. Int J Sci Stud 2017; 4 (11) 113-116
• 8 Modi JP. Postmortem examination. In: Subrahmanyam BV. ed. Modi's Medical Jurisprudence and Toxicology. 22nd ed.. New Delhi: Butterworths India; 1999: 91-126
• 9 Adler DE, Milhorat TH. The tentorial notch: anatomical variation, morphometric analysis, and classification in 100 human autopsy cases. J Neurosurg 2002; 96 (06) 1103-1112
• 10 Fisher CM. Brain herniation: a revision of classical concepts. Can J Neurol Sci 1995; 22 (02) 83-91
• 11 Corsellis JA. Individual variation in the size of the tentorial opening. J Neurol Neurosurg Psychiatry 1958; 21 (04) 279-283
• 12 Ono M, Ono M, Rhoton Jr AL, Barry M. Microsurgical anatomy of the region of the tentorial incisura. J Neurosurg 1984; 60 (02) 365-399
• 13 Knight J, Rayi A. Transtentorial Herniation. [Updated 2022 Jul 19]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023. Accessed November 23, 2023 at: https://www.ncbi.nlm.nih.gov/books/NBK560536/
• 14 Kernohan JW, Woltman HW. Incisura of the crus due to contralateral brain tumor. Arch Neurol Psychiatry 1929; 21: 247-287
• 15 Reid WL, Cone WV. The mechanism of fixed dilatation of the pupil. JAMA 1939; 112: 2030-2034