Can someone explain what this means? from mri - straightening and mild reversal of the normal cervical lordosis at c4. ?

In a normal x-ray/CT/MRI of the neck a gradual curve from the back of the head to the back. After a stressful event causes the neck muscles to tighten, the curve is less. By itself it is just the radiologist describing a finding that differs from a relaxed patient. Radiologists get fussed at if they just say "straightening of the neck or normal variant" .

The findings are consistent with a cervical strain/ sprain, and the curvature is straightened by muscle tightness or spasm. This would respond to conservative interventions such as physical therapy.