Surgery on the phrenic nerve

Goals and indications for intervention

Surgical interventions on the phrenic nerve (nervus phrenicus) are most commonly performed as alcoholization or complete transection of the nerve trunk, known as phrenicotomy.

The primary medical indication for these procedures is the presence of active tuberculosis localized in the lower or root regions of the lung.

Mechanism of therapeutic action (collapsotherapy):

• Following damage or destruction of the nerve fibers, persistent paralysis of the corresponding half of the diaphragm ensues.
• Deprived of innervation, the diaphragm relaxes and assumes an abnormally high position (high standing of the dome).
• The elevated diaphragm exerts upward pressure on the thoracic cavity, providing pronounced compression (collapse) of the affected part of the lung, which creates conditions for the healing of the tuberculous lesion.

Topographic and anatomical approach

Exposure of the phrenic nerve requires precise knowledge of the layered topography of the neck and is performed under local anesthesia. To ensure optimal access, the patient is placed in a supine position, the head is turned as far as possible to the healthy (contralateral) side, and the arm on the side of the intervention is pulled firmly downwards.

Step-by-step approach technique:

1. The surgeon makes a linear skin incision. The incision line must run parallel to the clavicle and be located exactly one finger's width above it.
2. The skin, subcutaneous adipose tissue, and superficial fascia of the neck, together with the platysma (platysma), are incised layer by layer.
3. The external jugular vein is visualized in the surgical wound. To avoid massive bleeding, the vessel is carefully isolated, ligated between two placed ligatures, and transected.
4. Next, the surgeon works in the anatomical space bounded by the clavicle inferiorly and the inferior belly of the omohyoid muscle superiorly.
5. Within this space, using a grooved probe, the second and third fasciae of the neck are safely incised.
6. To widen the access, the superficial cervical artery is bluntly retracted inferiorly, and the omohyoid muscle is retracted superiorly and laterally.

Nerve localization and alcoholization technique

After passing through all fascial barriers, the main anatomical landmark — the anterior scalene muscle (m. scalenus anterior) — is visualized in the medial corner of the wound. The trunk of the phrenic nerve lies directly on the anterior surface of this muscle, crossing it obliquely from the lateral margin to the medial one.

Stages of nerve alcoholization:

• The trunk of the n. phrenicus is carefully isolated from beneath the prevertebral fascia covering it.
• The isolated section of the nerve is thoroughly isolated from surrounding tissues by packing with gauze sponges. This prevents accidental contact of chemicals with neighboring structures.
• Using a very fine needle, the surgeon injects 1–2 ml of ethyl alcohol (at a concentration of 70% or 90%) into the nerve trunk.
• The injection is performed either strictly under the epineurium (outer sheath) or endoneurally (directly into the thickness of the nerve trunk).

The result of this chemical action is irreversible protein coagulation and persistent degeneration of nerve fibers, which ensures the prolonged paralysis of the diaphragm required for collapsotherapy.

Class and exam questions

What else to study on this topic

• Topographic anatomy of the neck fasciae (second, third, and prevertebral fasciae) in the supraclavicular access zone.
• The relationship between the phrenic nerve, the anterior scalene muscle, and the superficial cervical artery.
• Pathophysiology of collapsotherapy in active pulmonary tuberculosis.
• Differences between phrenicotomy, vagotomy, and sympathectomy.

Other topics in the «Neck Surgery» section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.