Hydrodissection of Recurrent Laryngeal Nerve: Case Series
Condition: Recurrent Laryngeal Nerve Injuries
MeSH terms: Laryngeal Nerve Injuries; Recurrent Laryngeal Nerve Injuries; Recurrence
Study type: Observational

Summary: 
      This study evaluates the hydrodissection technique in recurrent laryngeal nerve (RLN)
      dissection in thyroid surgeries. In this study hydrodissection of RLN was performed routinely
      in thyroid surgeries.
    

Detailed description: 
      Thyroid surgery is one of the most frequently performed surgical procedures. Recurrent
      laryngeal nerve (RLN) injury is the most annoying complication of thyroid surgery. According
      to literature 0.5-5% and 1-30% of patients is reported to have permanent or temporary RLN
      injury after the surgery, respectively.

      RLN innervates all intrinsic muscles of larynx with the exception of cricothyroid muscle.
      Injury of RLN causes vocal cord paralysis. Unilateral RLN injury causes hoarseness, but when
      RLNs are bilaterally damaged aspiration during swallowing or life threatening dyspnea can
      occur according to severity of glottal narrowing.

      Hydrodissection is described in laparoscopic cholecystectomy, cataract surgery, carpal tunnel
      syndrome treatment where meticulous dissection must be carried out as mentioned above. This
      technique helps exploring anatomical landmarks by gentle dissection without giving harm to
      tissues. In thyroid surgery hydrodissection is performed to dissect foamy planes and increase
      visualization of RLN by high velocity stream of warm saline. Despite being used extensively
      in routine clinical practice to our best knowledge no report evaluating hydrodissection in
      thyroid surgery exists in the literature up to date.

      In this study, investigators aimed to assess the incidence of RLN damage observed in our
      series by hydrodissection of RLN during thyroid surgery.

      To prevent RLN damage, a good knowledge of anatomy and surgeon's experience are crucial.
      Routine visualization of RLN along tracheoesophageal sulcus, following the course of RLN near
      suspensory ligament of berry ligament until entering the larynx is recommended to avoid RLN
      injury. But still some surgeons declare that visualization of RLN is not possible in all
      operations. Therefore staying close to thyroid capsule during thyroidectomy is considered to
      be a good surgical practice to preserve the nerve.

      Accurate knowledge of RLN anatomical variations, RLN landmarks such as relation of the nerve
      with inferior thyroid artery branches, berry ligament, inferior horn of thyroid cartilage
      during thyroidectomy, is essential as mentioned in the literature. Also inflammatory
      processes of thyroid (thyroiditis), large nodules, previous operations can change the course
      of nerve. Hence meticulous dissection of RLN should be performed. In simple thyroidectomies
      lateral or inferior dissection of RLN is the most common approach but in challenging cases
      such as large nodules, plunging thyroid gland, neck extension limitations, superior approach,
      craniocaudal dissection of RLN is accepted to be more appropriate . In our study, both
      lateral and superior approach were used, hydrodissection of foamy tissue and visualization of
      the nerve by removing blood and debris via high velocity stream of saline was the main point.

      Today, various methods of nerve monitoring and stimulation techniques are in use.
      Intraoperative nerve monitoring (IONM) significantly reduces iatrogenic RLN injury, helps
      identification of nerve especially in cases with anatomical variations and points early
      warning of nerve injury. But disadvantages of IONM like improper electrode position leading
      to nerve damage must be kept in mind. In the study investigators used IONM in only one case
      which had a story of RLN injury at the previously operated site. Hydrodissection of RLN is
      also helpful in use of IONM by allowing dissection of the planes gently just like the gas
      does in laparoscopy. In our country, since government does not pay for it, investigators
      cannot use IONM routinely. However hydrodissection is an easily applicable, non
      time-consuming and cheap technique.

      In this study consecutive patients underwent thyroidectomy for various thyroid diseases by
      one surgeon were included in the study. All the patients' demographic variables (age, sex),
      operation type (bilateral total thyroidectomy, hemithyroidectomy (total lobectomy and
      isthmectomy), completion total thyroidectomy, whether central neck compartment dissection was
      performed), pathology reports, nerves at risk were noted retrospectively. RLN exploration was
      routinely done to avoid nerve damage on the resected lobe side. Hydrodissection technique was
      performed while exploring RLNs differently from routine thyroidectomies. For hydrodissection
      a 10 ml syringe was used with a needle of 1 cm length. After ligation of middle thyroid vein
      and superior thyroid vessels, the thyroid lobe gently retracted medially and carotid arter
      laterally by retractors, hydrodissection was performed by high velocity stream of warm-normal
      saline to the foamy dissection area of RLN and berry ligament (Ethical approval was
      obtained).RLN detection and dissections were performed with hydrodissection. High velocity
      stream of normal saline is given to the dissection area by an 10 ml syringe. This dissected
      all the planes in the field like gas insufflation does in laparoscopic surgery . This
      technique helped RLN dissection without giving harm to any tissue and nerve itself. RLN
      integrity was checked by mobility of vocal cords 3 days prior to surgery, postoperative 3.
      day of surgery and if any movement change deteceted at postoperative 3. day, also
      reevaluation was made 1 month after the surgery. Also during extubation after operation
      completed, vocal cord movements are checked by direct visualization.
    

Intervention name(s): Hydrodissection
Intervention type(s): Procedure
Intervention description(s): high velocity stream of normal saline is given to the dissection area by help of 10 ml syringe
Observational model: Case-Control
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        all the patients undergoing to thyroidectomy for thyroid nodules
      
Keywords: thyroidectomy; recurrent laryngeal nerve; hydrodissection