Tear drop sign: (Repeat)
**Core Concept**
The tear drop sign, also known as the "tear drop" or "dropped" appearance, is a radiological finding observed in the lumbar spine, particularly on sagittal MRI or CT scans. This sign is associated with the herniation of an intervertebral disc, specifically the L4-L5 or L5-S1 discs, which can cause nerve root compression and pain.
**Why the Correct Answer is Right**
The tear drop sign is characterized by the herniated disc material protruding into the spinal canal, forming a teardrop-shaped structure. This occurs when the annulus fibrosus of the disc is ruptured, allowing the nucleus pulposus to leak out and compress adjacent nerve roots. The tear drop sign is often seen in cases of lumbar disc herniation, which can lead to radiculopathy, sciatica, and lower back pain.
**Why Each Wrong Option is Incorrect**
**Option A:** This option might be incorrect because the tear drop sign is not typically associated with spondylolisthesis, which is a different radiological finding characterized by the forward displacement of a vertebral body.
**Option B:** This option might be incorrect because the "empty sella" sign is a different radiological finding observed on MRI scans, characterized by the herniation of the pituitary gland into the sella turcica.
**Option C:** This option might be incorrect because the "scimitar sign" is a different radiological finding observed on CT scans, characterized by the curvature of a vertebral body or pedicle.
**Option D:** This option might be incorrect because the "Frankel grade" is a classification system used to describe the severity of spinal cord injuries, not a radiological finding like the tear drop sign.
**Clinical Pearl / High-Yield Fact**
The tear drop sign is an important radiological finding in the diagnosis of lumbar disc herniation, and it is often associated with radiculopathy and lower back pain. When interpreting MRI or CT scans, it is essential to recognize this sign and consider the clinical correlation with the patient's symptoms.
**Correct Answer:** C.