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A Reminder: A Case of Unexpected Difficult Airway Due to Lingual Tonsil Hypertrophy

The clinical value of bedside screening methods for predicting difficult intubation remains limited (1-3). Direct laryngoscopic intubation is difficult in 1%-4% and impossible in 0,05%-0,35%  of patients despite an apparently normal pre-operative assessment (4).
Lingual tonsils consists of lymphoid tissue located at the base of the tongue and can occasionally undergo inflammation and hypertrophy. Lingual tonsil hypertrophy (LTH) is a potential and perhaps even probable cause of unexpected difficult or impossible face mask ventilation and tracheal intubation  (cannot ventilate-cannot intubate) (5-9). LTH is usually not detectable during a routine pre-operative airway assessment (5,6,10). We report a case as a reminder of this.
 

Case report

A 56-year old woman with a benign pituitary tumour and acromegaly was scheduled for elective transphenoidal excision of tumour. She had mandibular prognathism, macroglossia, alteration of voice and enlarged hands and feet. She was otherwise healthy.  Preoperative airway evaluation revealed a Mallampati II , normal mouth opening and neck mobility. She was  able to protrude her mandible when requested to do so.

The patient received 40mg of oxazepam per os as premedication. Following establishment of routine monitoring and pre-oxygenation, anaesthesia was induced with remifentanil 0,5 ?g/kg/min and propofol 2 mg/kg iv. Face mask ventilation was easily accomplished, and neuromuscular blockade was produced with 8 mg vecuronium iv. At the first direct laryngoscopy, only the tip of the epiglottis could be seen (Cormack and Lehane grade 3). Two intubation attempts with a gum elastic bougie combined with external laryngeal manipulation resulted only in oesophageal intubation. 

We then used a fiberoptic bronchoscope orally, but were not able to visualise the laryngeal introitus or vocal cords. Jaw lift and manual protrusion of the tongue did not improve the situation. Nasal intubation was not an option because of the planned transphenoidal surgery. We also tried an intubating laryngeal mask (FastTrach?) and although the patient was easily ventilated using this, we were still not able to visualise the laryngeal introitus via fiberscope passed through the laryngeal mask. An otorhinolaryngologist also made one attempt at direct laryngoscopy using a straight blade, but failed to localise the laryngeal introitus or vocal cords.  In between these attempts the patient could easily be ventilated using a face mask. Minimal bleeding was detected.
Since this was a scheduled operation, and the patient was easy to face mask ventilate, tracheostomy did not seem appropriate. Surgery was cancelled and the patient was awakened uneventfully. In the postoperative care unit an awake endoscopy with the patient in a sitting position showed lingual tonsil hypertrophy, and we were then able to visualise the introitus laryngis and vocal cords.
The operation was rescheduled two weeks later. An awake oral fiberoptic tracheal intubation was performed successfully, followed by general anaesthesia. The surgery proceeded as planned and the postoperative period was uneventful

Discussion

LTH is often asymptomatic, although some patients may complain of a globus sensation, alteration of voice, chronic cough, snoring or obstructive sleep apnoea (5,6,9). Two thirds of patients with LTH have a history of previous palatine tonsillectomy. This may result in LTH, probably as a compensatory mechanism due to loss of palatine tonsils (6,9). LTH most often occurs in adults, especially in atopic individuals, but has also been reported in children (10,12). 

LTH can displace the epiglottis posteriorly and make mobilization of the epiglottis difficult. This is probably why patients with LTH may be difficult to intubate using conventional techniques. Fiberoptic intubation in already anaesthetised patients may be equally difficult (6).  Posterior displacement of epiglottis and redundant pharyngeal tissue may interfere with fiberoptic exposure, and with the onset of neuromuscular blockade the pharyngeal musculature relaxes, causing further posterior movement of the tongue and epiglottis. A similar failure of intubation through an intubating laryngeal mask has previously been reported (9).
Unlike palatine tonsils, lingual tonsils have no definite capsule. Continuous intubation and/or laryngeal mask airway insertion attempts can easily result in lingual tonsil swelling orbleeding (6,12), leading to a “cannot intubate- cannot ventilate” situation (5,6,13). We were aware of these possible  risks  and were very careful  not to traumatise tissue, and the patient was at all times easy to ventilate using a face mask. Although minimal bleeding was detected, the situation was deemed as safe throughout. 
LTH incidence is believed to be low, but since it is often asymptomatic, it  may be undetected until an event of general anaesthesia.  Ovassapian et al examined 33 patients with a history of unexpected difficult airway, and found that LTH was the only common factor (5).

Like other tonsils, lingual tonsils may become swollen during an acute inflammation and thus lead to an airway problem. There are reports of patients with LTH and unexpected difficult airways having been intubated some weeks earlier without problems (9,11). Awake fiberoptic intubation is recommended for all patients with known LTH in need of general anaesthesia. In an unexpected difficult intubation situation a  ENT laryngoscope is recommended (6).

Acromegaly is known to be associated with increased risk of a difficult airway (14) and the incidence of difficult intubation is reported to range from 10 to 30 %. This is attributed to prognathism, macroglossia and thickening of laryngeal and pharyngeal soft tissue, and  LTH in our patient could have contributed to the difficulties encountered. There might  be a synergistic effect of the acromegaly, making the lingual tonsils even more hypertrophic than usual (15). However, because of the preoperative findings, and endoscopically confirmed large LTH, we believe that the LTH as such was the major reason to our difficulties,  chiefly causing a posterior displacement of the epiglottis.  LTH with the associated risks of bleeding and swelling should always be borne in mind when difficulties in visualising the vocal cords with a rigid laryngoscope are met.

References
 

1. Shiga T, Wajima Z, Inoue T, Sakamoto A. Predicting Difficult Intubation in Apparently Normal Patients. A meta –analysis of bedside screening test performance.  Anesthesiology 2005; 103: 429-37
2. Karkouti K, Rose DK, Wigglesworth D, Cohen MED MER. Predicting difficult Intubation: a multivariable analysis. Canadian Journal of Anesthesia 2000; 47: 730-739
3. Arné J, Descoins P, Fusciardi J et.al. Preoperative assesment for difficult  intubation in general and ENT surgery: predictive value of a clinical multivariate risk index. British Journal of Anaesthesia 1998; 80: 140-149
4. Benumof JL. Management of the difficult adult airway. With special emphasis on awake tracheal intubation. Anesthesiology 1991; 75: 1087-110
5. Ovassapian A, Glassenberg R, Randel GI, Klock A, Mesnick P, Klafta J. The unexpected difficult airway and lingual tonsil hyperplasia: A case series and a review of the literature. Anesthesiology 2002; 97(1): 124-132
6. Davies S, Ananthanarayan C, Castro C. Asymptomatic lingual tonsillar hypertrophy     and difficult airway manangement: a report of three cases. Canadian Journal of Anesthesia 2001; 48: 1020-1024
7. Nakazawa K, Ikeda D, Ishikawa S, Makita K. A case of difficult airway due to  lingual tonsillar hypertrophy in a patient with Down’s syndrome. Anesthesia ?Analgesia 2003; 97 (3): 704-705
8. Shamaa MA, Jefferson P, Ball DR. Lingual tonsil hypertrophy: airway management. Anaesthesia 2003; 58: 1134
9. Asai T, Hirose T, Shungu K. Failed tracheal intubation using a laryngoscope and intubating laryngeal mask. Canadian Journal of Anesthesia 2000; 47: 325-328
10. Arrica M, Crawford M. Complete upper airway obstruction after induction of anesthesia in a child with undiagnosed lingual tonsil hypertrophy. Pediatric Anesthesia 2006; 16 (5)
11. Rosenstock C, Kristensen MS. Decreased tongue mobility – an explanation for difficult endotracheal intubation. Acta Anaesthesiologica Scandinavica 2005; 49:
          92-94
12. Tokumine J, Sugahara M, Ura I, Takara M, Oshiro T. Lingual tonsil hypertrophy with difficult airway and uncontrollable bleeding. Anaesthesia 2003; 58; 390
13. Jones DH, Cole SD. Unanticipated difficult airway secondary to lingual tonsillahyperplasia. Anesthesia ? Analgesia1993; 77: 1285-1288
14. Nemergut EC, Zuo Z. Airway management in patients with pituitary disease: areview of 746 patients. J Neurosurg Anesthesiol 2006; 18 (1): 73-77
15. Benumof's Airway Management, 2nd Edition  2007 By Carin A. Hagberg, MD, ISBN: 0323022332 ISBN-13: 9780323022330 Publisher: Elsevier. Difficult airway in neurosurgery 961-983