|Year : 2011 | Volume
| Issue : 4 | Page : 416-418
Partial facial nerve paralysis after laparoscopic surgery under general anaesthesia
Dalim Kumar Baidya, Debesh Bhoi, Renu Sinha, Rahul Kumar Anand
Department of Anesthesia and Intensive Care, All India Institute of Medical Sciences, New Delhi, India
|Date of Web Publication||13-Sep-2011|
Dalim Kumar Baidya
Hostel 8, Room No. 67, All India Institute of Medical Sciences, New Delhi - 110 029
|How to cite this article:|
Baidya DK, Bhoi D, Sinha R, Anand RK. Partial facial nerve paralysis after laparoscopic surgery under general anaesthesia. Indian J Anaesth 2011;55:416-8
|How to cite this URL:|
Baidya DK, Bhoi D, Sinha R, Anand RK. Partial facial nerve paralysis after laparoscopic surgery under general anaesthesia. Indian J Anaesth [serial online] 2011 [cited 2013 May 21];55:416-8. Available from: http://www.ijaweb.org/text.asp?2011/55/4/416/84844
Peripheral nerve injury following anaesthesia can lead to functional disability and anxiety to the patient and litigation to the concerned medical team. We report a case of partial facial nerve palsy following uneventful surgery under general anaesthesia.
A 62-year-old female, weighing 65 kg, was scheduled for total laparoscopic hysterectomy and cholecystectomy for dysfunctional uterine bleeding and cholecystitis, respectively. She had type II diabetes mellitus for 3 years and her blood sugar was controlled on tablet Metformin 250 mg twice-daily. Airway examination revealed mouth opening 4 cm, modified mallampatti grade II with adequate neck movement. Chest X-ray, electrocardiography and haematological and biochemical investigations were normal.
Anaesthesia was induced with intravenous fentanyl 100 mg and propofol 80 mg. Bag and mask ventilation was started. Muscle relaxation was facilitated with vecuronium 6 mg. Jaw thrust and tight mask seal with right hand was required for adequate mask ventilation. After 3 min of mask ventilation, the trachea was intubated with a 7.5 mm cuffed endotracheal tube (ETT) and, after confirmation of bilateral equal air entry, the ETT was fixed at 18 cm at the right corner of the mouth. Anaesthesia was maintained with oxygen, air and isoflurane, with intermittent doses of morphine and vecuronium. Surgery was uneventful and lasted for 4 hrs. At the end of surgery, after reversal of neuromuscular blockade, the trachea was extubated and the patient was shifted to the postanaesthesia care unit.
On postoperative day 1, the patient noticed deviation of lower lip towards the left on opening the mouth [Figure 1]. On examination, she had a 2 cm × 2 cm area of decreased sensation over the right lower corner of the mouth. There was no spillage of liquids from the mouth, but mild weakness was noted on blowing a whistle. On examination, the rest of the facial nerve branches and other cranial nerves were normal. Distal facial nerve branch paresis (mental and buccal branch) was provisionally diagnosed after neurology evaluation. She was reassured and discharged on postoperative day 4 with the advice of regular follow-up in the neurology department. Complete recovery of the facial nerve was observed after 6 weeks.
Various mechanisms for nerve injuries have been proposed, like ischaemia, direct mechanical compression, stretching of the nerve due to faulty positioning, direct needle trauma or injection of neurotoxic material. 
The presence of diabetes is also associated with an increased incidence of nerve injury. Other risk factors include intraoperative hypotension, hypovolaemia, hypoxia, hypothermia or electrolyte imbalance. ,
In the present case, although the nerve injury was minor, even after reassurance of reversible nature, the patient was distressed knowing the possibility of thermal or mechanical injury to the lip and buccal mucosa. Although the patient was diabetic, she did not have any peripheral neuropathy, with well-controlled perioperative blood sugar. There was no episode of intraoperative hypotension, hypovolaemia, hypoxia, hypothermia or electrolyte imbalance that could aggravate nerve injury. None of the anaesthetic agents or adjuvants administered is known to cause acute neuropathy.
The possible aetiology could be injury to the mental nerve by the rim of the mask, compression/stretching of the mandibular branch at the angle of the jaw or buccal branch over the mandibular ramus by forward jaw thrust.
After exit from the stylomastoid foramen, the facial nerve enters the parotid gland over the mandibular ramus and gives off four branches; the temporal and zygomatic branch turn upwards, whereas the buccal and mandibular branch turn downwards to pass over the mandibular ramus. These two branches are susceptible to injury during mask ventilation either by direct pressure over the nerves behind the ramus of mandible or due to stretching caused by forward traction on the jaw. Certain anatomical variations make these branches more susceptible to injury. The mandibular branch often runs high in relation to the angle of the mandible. But, in rare cases, it may run low near the angle of the mandible, where it can be easily compressed against the bone. In another variation, the facial nerve lies superficial rather than deep to the parotid gland. This renders the buccal branch liable to pressure injury from a too tightly fitted mask or head strap. ,
Two cases of lower lip numbness have been reported, which were probably due to excessive pressure by the rim of the mask directly on the mental nerve bilaterally near the mental foramina. In both the cases, entire surgeries (which lasted for 30 and 45 min) were performed under mask with oropharyngeal airway in situ.
Glabaur reported a case of bilateral facial nerve palsy following general anaesthesia provided through a mask for 75 min in a spontaneously breathing patient. The mask was supported with Connell harness and bilateral digital pressure was exerted behind the angle of the jaw for the entire period of anaesthesia. The paresis resolved after 3 weeks. 
Fuller and Thomas reported two cases of facial nerve weakness. Postoperatively, one patient manifested weakness and asymmetry of face with impaired control of food during chewing and the second patient had minor weakness of one side of the mouth. Forward digital pressure was given behind the angle of mandible for 30 min in the first patient and 10 min in the second patient. Complete recovery was observed after 3 months and 3 weeks, respectively. 
In the present case, facial nerve paresis occurred with only 3 min of forward digital pressure at the right angle of jaw with tight mask seal, and complete recovery took 6 weeks. The clinical features in the present case suggest involvement of mental nerve and, possibly, some fibres of the buccal branch.
In conclusion, partial facial nerve paresis is a rare and reversible complication and can happen even after a few minutes of mask ventilation. Therefore, vigorous jaw thrust with very tight application of mask should be avoided whenever possible.
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