Using the Deep Temporal Nerves Versus the Masseteric Nerve for Correction of Eyelid Paresis.

Type of the study: Prospective Interventional Study (clinical trial)

Intervention Model Description:

Patients will be randomized into two groups according to the surgical procedure performed as follows:

• Group A: Deep temporal nerves.
• Group B: Masseteric nerve.

Allocation and Randomization:

Twenty-four patients will be randomly assigned to Group A or Group B (2 equal groups).

Simple randomization will be performed before surgery by a research nurse using the closed-envelope technique.

Twenty-four closed envelopes will be used, each 12 of them carries one of the 2 groups. Closed envelope will be randomly withdrawn the night before surgery to assign the patient to his specific group.

Study Setting: Plastic and Reconstructive Surgery Department, Assuit University Hospital

Study subjects:

Inclusion criteria:

1. Facial nerve paresis with upper eyelid affection.
2. Patients are generally fit with no other disease interfere with microsurgery.
3. Electromyography of eyelid showing fibrillations. b. Exclusion criteria:
4. Patient with other medical or mental disease causing generalized paralysis. 2. Syndromic cases. 3. Patients are generally unfit or with any disease interfere with microsurgery.
5. Electromyography of eyelid showing no fibrillations.

Sample Size Calculation: 24 Sample size was calculated using G power program version 3.1.9.4 (6) in order to detect a significant difference in mean of palpebral fissure height (one of main assessed outcomes in the study ) between two groups under the study , assumed effect size 0.6 based on clinical assumption ( novel study ), α error 0.3 , power 0.80, and allocation ratio 1: 1.

Twenty-two patient plus 10% for dropouts to make total twenty-four (12 patient for every group).

Study tools

All patients in this study are subjected to:

Pre-operative Assessment:

1. Patient history.
2. All patients will do preoperative clinical and neurophysiological assessments of mimetic muscle function and donor nerve status (the ipsilateral deep temporal nerve. The neurophysiological tests will include needle Electromyography (EMG) for recruitment of residual motor unit action potential. If there are no fibrillations patients will have another surgical procedure.
3. The trigeminal motor component will be tested by palpating the temporalis muscle during chewing and via needle EMG of the temporalis muscle to verify availability as a donor motor nerve.
4. Photographic documentation preoperative using standardized frontal face view and adding a scale to photo to measure the palpebral fissure size during three states normal eye opening, resting eye closure and forced eye closure using ImageJ (image processing and analysis in java) computer software (7).
5. Ophthalmological assessment of the affected eye for detection of redness, ulcer, etc.

Surgical procedure:

Group A We will avoid the use of muscle relaxants to induce anaesthesia and employ an electro-stimulator to identify the deep temporal nerves and the facial nerve branches supplying the eyelid on the affected side.

Exploration on the affected side a facelift-type incision will be performed, and an anterior subcutaneous flap is then will be lifted for several centimetres. In the inferior zygomatic region, the plane of elevation is deepened into the sub-SMAS plane and a composite flap elevated for several centimetres. Following elevation in this plane, the distal facial nerve branches will be identified. The distal portion of the zygomatic nerve is usually located midway between the oral commissure and the helical root. and was confirmed by nerve stimulator.

The deep temporal fascia and temporalis muscle will be incised along the temporal fusion line and will be reflected from the skull to expose the divisions of the deep temporal nerves and the longest branch was traced and prepared for anastomosis end to end with the zygomatic branch after confirming the eyelid supply(8).

Then suction drain will be put and will be removed after 24 hours. Group B The same procedure except tracing the masseteric nerve related to masseter muscle and anastomosis will be the same (9).

Post-operative All patient will receive physiotherapy and post-operative follow up to detect any wound complication.

Evaluation (After 6 months from the operation)

1. Photo documentation: measurement of the palpebral fissure size during three states normal eye opening, resting eye closure , forced eye closure will be done adding eye closure during mastication to compare with preoperative resting eye closure measure using ImageJ (image processing and analysis in java) computer software(7).
2. Donor site morbidity.
3. Follow up Ophthalmological assessment.

Complications:

1. General surgical complication.
2. General complication due to general anaesthesia.
3. Specific complication:
4. Delayed healing of nerve anastomosis.
5. Affection of mastication.
6. No postoperative improvement.

Research outcome measures:

1. Primary (main): Comparing the outcomes on palpebral fissure size between the deep temporal group and the masseteric group after 6 months from the surgery.
2. Secondary (subsidiary):
3. Procedure-related morbidity and mortality.
4. Operative time and hospital stay.