Bruzinski’s sign is a common neurological test in which the patient is asked to lie supine with both lower extremities naturally straight and relaxed while the physician holds the patient’s neck in one hand and flexes the patient’s cervical spine forward. If there is flexion of the hip and knee during cervical flexion, the sign is positive. Bruzinski’s sign, also known as Kellnig’s sign, is one of the common tests used in neurology. If the pathologic sign is positive, it is most often indicative of a cranial lesion, such as encephalitis, meningitis, or subarachnoid infection. If there are significant positive pathological signs, most of them require a cranial CT or MRI. There are also clear contraindications when performing Bruzinsky’s sign, which is prohibited if the patient has very severe cervical spine disease or a history of severe cervical spine trauma. If the subarachnoid infection is very severe and the patient has a very severe coma, this pathological sign may not be elicited and needs to be judged in conjunction with the imaging data.