Cervical variations of the phrenic nerve.

Area of Science:

• Anatomy
• Surgical Neurology
• Regenerative Medicine

Background:

• Selective reinnervation of the posterior cricoarytenoid muscle using a single phrenic nerve rootlet shows promise in animal models for restoring physiologic motion.
• Clinical application is hindered by incomplete understanding of the phrenic nerve's cervical anatomy.

Purpose of the Study:

• To investigate the anatomical variations of the phrenic nerve's cervical rootlets.
• To provide detailed data on phrenic nerve branching patterns for potential surgical reinnervation procedures.

Main Methods:

• A prospective study involving dissection of 111 cadaveric necks (56 cadavers, 88 embalmed, 23 unembalmed).
• Detailed analysis of phrenic nerve rootlet lengths (C3, C4, C5) and branching patterns.
• Comparison of rootlet lengths between embalmed and unembalmed specimens.

Main Results:

• Significant variability in phrenic nerve rootlet lengths and patterns was observed, with eight unique patterns identified.
• The most common pattern involved single C3 and C4 rootlets (26%).
• Embalmed cadavers exhibited shorter C3 and C4 rootlet lengths compared to unembalmed specimens (P = .02 and P = .03, respectively).

Conclusions:

• The cervical anatomy of the phrenic nerve is highly variable.
• This variability must be considered for successful clinical translation of phrenic nerve reinnervation strategies.