Which medical condition in a client's history poses a contraindication for an MRI of the cervical vertebra?

The presence of a pacemaker is a significant contraindication for an MRI of the cervical vertebra due to the strong magnetic fields used in the MRI procedure. Pacemakers contain metal components and electronic circuitry that can be affected by the magnetic field, potentially leading to malfunction of the device, interference with pacing, or even heating of the metal parts. This not only endangers the patient's health by jeopardizing the function of the pacemaker but could also pose risks during the imaging process.

In contrast, conditions such as a history of hypertension, recent shoulder surgery, or chronic migraines do not inherently affect the safety or effectiveness of the MRI procedure. While these conditions may require monitoring and consideration during patient evaluation and care, they do not have the same direct and urgent contraindication as the presence of a pacemaker does.