Thyroglossal cyst is a remanant of the thyroglossal tract. The thyroid gland starts its descent in early fetal life. The thyroglossal duct starts from Foramen caecum (located on junction of anterior two third and posterior one third of tongue) and descends down to lower neck where the isthumus of thyroid lies over the second and third tracheal rings [1].

During this time, hyoid bone has not formed yet, making the descent track variable passing behind, infront or through the final position of hyoid bone [2]. The thyroglossal tract obliterates by the 10^th week of gestation [3]. Thyroglossal duct cyst is a remnant of this track and may therefore be found any place in or adjacent to the midline from the tongue base to the thyroid isthmus [4]. Sometimes they may contain residually thyroid tissue.

A 63 year old male presented with a midline neck swelling. The sub hyoid swelling was insidious in onset, was initially pea sized and gradually progressed to a lemon sized swelling. The mass moved with deglutition and on tongue protrusion (IMAGE 1). No history of pain over swelling was present. No history of any discharge over swelling was seen. Patient is a chronic smoker and betel nut chewer. He had white patches in both sides buccal mucosa and presented with difficulty in opening mouth (IMAGE 2). He had grade 3 Trismus. The patient was a diagnosed case of oral submucous fibrosis on treatment.

On examination of the swelling in the neck, it was round in shape, smooth, margins free from underlying skin and structure, fluctuation was positive and transillumination was negative.

IMAGE 1 – PREOPERATIVE PICTURE SHOWING MIDLINE SWELLING NECK

IMAGE 2 – PREOPERATIVE PICTURE SHOWING WHITE PATCHES OVER BUCCAL MUCOSA WITH TRISMUS

FNAC showed hypercellular  fluid composed of inflammatory cells and infiltrate of neutrophil macrophage with lymphocytes, histiocytes and leukocytes . USG of the neck was done which suggested a cystic lesion in the midline neck.

The patient was planned for Sistrunk operation. All the preanaesthetic investigations were done and patient was operated under general anaesthesia( IMAGE 3 &4). Sample was sent for histopathological examination.

Pre-anaesthetic evaluation was done for the patient wherein submucosal fibrosis due to a long history of betel-nut chewing was found. Patient was also a chronic smoker. The mouth opening of the patient was less than 1cm with grade 3 trismus. There was no other significant history or examination finding. Patient was planned and counselled for awake fibreoptic nasal intubation (AFOI) with general endotracheal anaesthesia. Informed written consent for surgical procedure and anaesthetic management was obtained.

On the day of surgery, after obtaining a wide-bore i.v. access, the patient was given 0.01mg/kg inj. Midazolam i.v. as anxiolytic and 4 mcg/kg Inj. Glycopyrrolate i.m. as an anti-sialogogue 60min. before shifting into the operating room. After shifting the patient on the operating table, ASTM standard monitors were secured. We followed the “STOP” strategy [1] for AFOI recommended by the Difficult Airway Society [2] which included the following components:

Sedation : Inj. Dexmedetomidine loading dose 1 μg/kg given over 10–20 min followed by an infusion starting at 0.7 μg/kg/hr.

Topicalisation: Oxymetazoline 0.05% nasal spray 2 puffs in each nostril, Inj. Lidocaine 10% spray 2-3 sprays to each tonsillar pillar for glossopharyngeal nerve block, nebulisation with 4ml of 4% Inj. Lidocaine and “SAGO” technique with 2% Inj. Lidocaine via epidural catheter inserted via suction port of Fibreoptic scope.

Oxygenation: Para-oxygenation was achieved with THRIVE technique using high‐flow nasal cannula (HFNC) (oxygen flow: 50 L/min).

Optimising Performance: With the patient in semi-recumbent position, the primary anaesthesiologist, standing in front of the patient, secured the airway with a 7.5mmID cuffed portex endotracheal tube.

Anaesthesia was maintained with N₂O:O₂=50:50 with 1 MAC Isoflurane and Inj. Vecuronium. Muscle Relaxation was reversed with Inj. Neostigmine 0.05mg/kg i.v. with extubation over a ventilating gum-elastic bougie.

IMAGE 3 – INTRAOPERATIVE PICTURE

IMAGE 4 – EXCISED SPECIMEN

Histopathology show cystic wall lined with ciliated pseudostratified columnar cells underlined with basal membrane and thin fibrous tissue with benign thyroid follicles confirming preoperative diagnosis of thyroglossal cyst ( IMAGE 5).

IMAGE 5 – MICROPHOTOGRAPH SHOWING  CYST WALL AND EPITHELIAL LINING.

The patient was followed up monthly for 6 months with proper healing and no sign of recurrence.

The occurrence of thyroglossal cysts may be less frequent in elderly patients. The Sistrunk procedure remains the gold standard surgical intervention for the majority of cases[5]. There can be serious complications including infection and malignant transformation[6]. Sistrunk method, a standard procedure for removal of thyroglossal cyst was employed.

The cyst is usually located in subhyoid region with the tract passing from the middle portion of the hyoid bone and reaching out to the mouth floor[7]. The cyst tract with part of bone was removed . The bone needs to be freed from its attachment of supra and infrahyoid muscle and deep fascia of the neck during the procedure [8]. With a 2 to 3cm transverse incision over the skin crease the duct and cyst was removed including it’s branches[9]. Prognosis is usually excellent with recurrence rate of about 10 percent after surgery [10].

Anaesthetic management for the case included Awake tracheal intubation (ATI) which is defined as successful placement of a tracheal tube in a patient who is awake and breathing spontaneously [11]. It comprises several techniques, using both flexible bronchoscopy and videolaryngoscopy, aimed at successfully securing the airway of patients in whom factors may predict difficult airway management [12]. Awake tracheal intubation remains the gold standard for management of the anticipated difficult airway[13]. ATI is indicated in any patient with predictors of difficult tracheal intubation or face mask ventilation which may stem from pre-existing patient factors or as a consequence of the presenting pathology [14]. In the case we managed, we preferred awake fibreoptic nasal intubation because of minimal mouth opening and front-of-neck swelling which hindered opting for retrograde wire intubation, videolaryngoscope or supraglottic airway. Nasal intubation can lead to patient discomfort, limitation in the size of tracheal tube that can be placed through the nares and difficulty passing the nasal passages which can cause epistaxis. Careful airway preparation, sedation, consideration of ergonomics and procedural skills can significantly improve the success rate of ATI [15].

Recurrence in about 10 percent of cases, which can be due incomplete excision, rupture  intraoperatively and presence of infection. Laryngotracheal injury a rare but grave complication can lead to dysphagia, dyspnoea and voice difficulties. It can occur if the surgeon accidentally resects the thyroid cartilage instead of hyoid bone. Another rare complication is hypoglossal nerve injury( cranial nerve 12^th) leading to paralysis  of one side of tongue with tongue deviation on same side of lesion on tongue protrusion. To avoid this resection should be performed medial to lesser cornu of hyoid bone.

Patient advised not to lift heavy weights for two to six weeks. Pain medication can be prescribed to alleviate pain and a suitable antibiotic cover is used. A surgical drain is usually placed which is removed few days after surgery.

Thyroglossal cyst although a childhood disease can even present in elderly population. It should be considered as a differential diagnosis in solitary midline swelling or paracervical lesion between thyroid gland and the hyoid bone.  Sistrunk procedure is the surgical treatment of choice.

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