From the Research
The teddy bear sign has a reported presence in 40% to 78% of cases, which can be used to estimate its sensitivity and specificity in medical diagnosis, particularly in the context of internal carotid artery localization in transsphenoidal pituitary and anterior skull base surgery. The "teddy bear" sign, as described in the study by 1, refers to the appearance of the internal carotid arteries on axial computed tomography (CT) scans, resembling a teddy bear. This sign is useful for preoperative identification of anatomy that may predispose patients to a higher risk of internal carotid artery injury during surgery.
The study by 1 found that a grade 2 (strongly positive) "teddy bear" sign was identified in 40% of cases at the level of the superior pituitary fossa, 78% at the inferior pituitary fossa, and 59% at the clivus. A grade 1 (intermediate) sign was seen in 23.5%, 7.5%, and 10% of cases, respectively. In 5% of cases, the sign was grade 0 at all levels, indicating poor intraoperative localization of the internal carotid artery.
While the study by 1 does not provide direct estimates of sensitivity and specificity, it suggests that the "teddy bear" sign can be a useful tool for identifying patients at risk of internal carotid artery injury during surgery. The presence of a grade 2 sign predicts good intraoperative localization of the internal carotid artery, which can inform the safe lateral limit of sellar bone resection.
In contrast, the studies by 2, 3, 4, and 5 provide more general information about the concepts of sensitivity, specificity, and predictive values in medical research, but are not directly relevant to the "teddy bear" sign in the context of internal carotid artery localization.
Therefore, clinicians should use the "teddy bear" sign as a useful preoperative tool for identifying anatomy that may predispose patients to a higher risk of internal carotid artery injury during transsphenoidal pituitary and anterior skull base surgery, and consider it as one component of a comprehensive diagnostic approach that includes detailed history-taking, collateral information, and psychological assessment.