Which one of the following statements is true?

The statement that all comatose patients require a head CT scan before a lumbar puncture is performed is generally considered true in clinical practice, primarily to rule out the possibility of increased intracranial pressure or mass lesions that could lead to brain herniation during the procedure. Performing a lumbar puncture in the presence of a mass effect can be lifesaving; however, it may also pose significant risk.

In cases of coma, assessing the cause is critical, and neuroimaging helps ensure that conditions leading to potential complications from the lumbar puncture are ruled out first. This approach prioritizes patient safety and the prevention of avoidable harm, making this statement align with established medical protocols.

Other options have specific issues that lead to their inaccuracy. Not all cases of acute Guillain-Barré syndrome necessitate intensive care unit admission; while some may require close monitoring, others can be managed on a general medical floor. The positive grasp reflex does not exclusively indicate frontal lobe damage as it can correspond with other neurological findings, and cerebellar hemispheric lesions typically produce deficits that are ipsilateral or on the same side rather than contralateral.