Question

Following the administration of an interscalene block, the patient reports dyspnea. This most likely results from the paralysis of which cranial nerves?

1) First
2) Second
3) Third
4) Fourth
5) Fifth
6) Sixth

Answer 1

Dyspnea after an interscalene block is typically related to phrenic nerve paralysis, which is not related to any cranial nerves. It occurs due to the blockade's effect on cervical spinal roots, which can lead to diaphragmatic paralysis and reduced respiratory function.

Step-by-step explanation:

Dyspnea following an interscalene block is most likely due to paralysis of the diaphragm, which is primarily innervated by the phrenic nerve. The phrenic nerve is not a cranial nerve, but rather a nerve that originates from the cervical spinal roots (C3, C4, and C5). Since cranial nerves do not innervate the diaphragm, none of the listed cranial nerves (first through sixth) are responsible for diaphragmatic paralysis and the subsequent dyspnea. If we instead focus on the cervical nerves associated with the diaphragm, the nerve roots most closely connected to the question posed would be the third and fourth cervical nerves (C3 and C4).

An interscalene block affects the brachial plexus, and if it spreads to the phrenic nerve, it can cause paralysis of the hemidiaphragm on the same side. This can result in dyspnea due to decreased lung capacity and ineffective ventilation. Additionally, individuals with pre-existing lung conditions or compromised respiratory function may be more significantly affected by hemi diaphragmatic paralysis.