MACROGLOSSIA is an infrequent but potentially lethal postoperative complication following intracranial neurosurgical procedures in the posterior fossa. 1–11The incidence of this complication has been estimated to be 1%9; however, the complication may be underreported, and its actual incidence is unknown. The etiology of macro- glossia is uncertain, and has been attributed to arterial compression, venous compression, mechanical com-pression, or to neurogenic origin. 6,9Recently, Kuhnert et al. described a case of massive postoperative macroglossia following a C1-2 laminectomy using the sitting position in a patient with Crouzon syndrome. Although the etiology remained unclear, the case revived interest in this complication. 10
This report documents our experience with a patient who experienced this complication during her first procedure for resection of an acoustic neuroma, and who returned 9 yr later for resection of the recurrent tumor. In addition, another case of a “near miss” is described. These two cases lend new insight to the etiology of this complication, and suggest that venous obstruction leading to arterial insufficiency and resulting in reperfusion injury is the primary etiology in many of these cases.
A 43-yr-old overweight (170-cm, 100-kg) woman presented for left suboccipital craniectomy for an acoustic neuroma (2 x 2 cm). The patient was placed in the park-bench position (semiprone lateral with the left side up and the head flexed). A soft bite block (rolled-up gauze) was inserted after induction of anesthesia. Surgery and anesthesia were uneventful and lasted for 10 h. At the end of the procedure the patient awoke in the operating room, and the trachea was extubated shortly afterward. The tongue was noted to be large but not swollen, and the airway was patent. Thirty minutes after arrival in the recovery room the patient reported the inability to breathe, was noted to be stridulous. The tongue, lower face, and neck were swollen. Direct laryngoscopy revealed a massive swollen tongue and a diffuse edema in the base of the tongue and in the supraglottic structures, and the larynx could not be observed. After multiple attempts, the trachea was reintubated. The tongue continued to swell during the next 24 h, and eventually protruded well out of the oral cavity. To prevent desiccation, tongue was wrapped with wet gauze hourly. The submandibular area and the neck were edematous. Multiple allergy testing and investigations, including C1 esterase-inhibitor levels to rule out hereditary angioneurotic edema, were conducted with negative results. On day 9, tracheostomy and exploration of the neck were performed. The only finding was a small area of necrosis in the base of the tongue. The swelling began to subside on day 12. By day 23, the tongue had returned to near-normal size and the patient was discharged.
Nine years later the patient returned for surgery on the recurrent left acoustic neuroma. The mouth opening was limited from mild contracture, and there were dental impressions on the right border of the tongue, which appeared normal. We proceeded with nasal tracheal intubation using sedation, and placed the patient in the sitting position for the surgical procedure. In addition to a multiorifice central venous catheter, a retrograde catheter was inserted into the right jugular bulb. Simultaneous monitoring of central venous pressure and jugular venous pressure (JVP) allowed for the diagnosis of venous obstruction (should it occur); central venous pressure would remain unchanged whereas JVP would increase, thereby creating a gradient. Supine extreme flexion of the neck with the head turned to the right created a gradient of 8 mmHg. The patient was placed in the sitting position with head turned to the left to facilitate surgical exposure. A soft bite block was placed. The transducer for JVP was placed at the level of the jugular bulb (at the level of the mastoid process). Comparison with central venous pressure indicated that there was no venous obstruction, and the JVP remained negative throughout the procedure. Surgery lasted 9.5 h. No swelling was observed in the tongue or neck at the end of the procedure. After 30 min of observation the nasotracheal tube was removed. The postoperative course was uneventful.
A 50-yr-old woman underwent a suboccipital craniectomy for the resection of a posterior fossa arteriovenous malformation. After the uneventful induction of anesthesia, the patient was placed in the sitting position. Approximately 30 s after placement of the head in the Mayfield head-holder and flexion of the neck, a blue discoloration developed above the neck. The lips were blue and the tongue began to protrude between the teeth. The pulse oximetry remained at 100%. The flexion of the neck was quickly reduced and the head was brought back toward a more-neutral position by approximately 10 °. The patient’s color returned to normal almost instantaneously. The surgical procedure and the patient’s recovery were otherwise uneventful.
As recently suggested by Kuhnert et al. , 6the etiology of macroglossia may be multifactorial. Factors that have been implicated can be classified as (1) local mechanical compression (by teeth, oropharyngeal airway, endotracheal tube, throat pack) interfering with venous or lymphatic drainage of the tongue; (2) regional venous obstruction (excessive neck flexion, head-down position); and (3) various combinations of these two factors. Moore et al. 9and Ishiyama et al. 11observed that the complication occurred only with posterior fossa surgery, and proposed that macroglossia may be neurogenic in origin; however, neither report provided evidence to support this hypothesis.
A summary of the neurosurgical cases reported in the literature, including the present case, is shown in table 1. Of the 16 cases of macroglossia reported, all but one involved posterior fossa procedures. The most plausible explanation may be that the surgical approach to posterior fossa necessitates positioning that may lead to venous obstruction. Irrespective of the position used, surgical access to the posterior fossa frequently necessitates flexion and rotation of the neck that may impinge on the venous circulation, an obstruction that cannot always be recognized by external inspection. Although the original cases reported involved the sitting position, 1subsequent cases have been reported that use other positions (table 1).
Analysis of the onset of macroglossia in the 16 cases suggests that there are two patterns. We hypothesize that, in the milder form, there is local venous or lymphatic congestion caused either by local compression or by venous obstruction (interfering with venous drainage via the lingual veins), and leads to an isolated swollen tongue. In this situation, the onset of macroglossia tends to be immediate. Airway obstruction is unlikely to occur because the swelling can be immediately recognized and extubation of the trachea can be postponed. In the more severe form, there is regional venous obstruction with or without local compression.
The lingual arteries run at the base of the tongue, deep to the lingual veins that drain into the ipsilateral internal jugular vein or into the facial vein. In susceptible patients the initial venous congestion may lead to the development of regional ischemia by compressing these arteries. This is followed by reperfusion injury. The lymphatics follow the vessels and may play a contributory role. The venous obstruction need not be complete and cerebral swelling may or may not be apparent. Because the reperfusion injury does not occur until the venous congestion is relieved, the onset of macroglossia is often delayed by approximately 30 min or more. The injury tends to be severe, and areas other than the tongue are often involved, as in our case. Of the 16 cases reviewed and tabulated in table 1, only 30% (5 of 19 cases) are of immediate onset, and the majority (70%) are delayed.
In the first case, the patient’s second procedure presented us with a dilemma. Using a jugular bulb catheter, we were able to monitor the JVP to ensure good venous drainage. Although a direct cause and effect cannot be established, the presence of low JVPs and the uneventful postoperative course suggest that venous congestion was an important etiologic factor in the events following the first procedure.
Our second case confirms that venous obstruction from excessive flexion of the neck can occur when the patient is placed in the sitting position. Here, the venous obstruction was nearly complete and immediate, and allowed the diagnosis to be made and the complication of macroglossia to presumably be prevented.
In a letter to the editor, Drummond 10reiterated the importance of using a soft bite block instead of an oropharyngeal airway, which was suggested by McCallister et al. 1Although we agree with this recommendation, we also note that it did not prevent the occurrence of macroglossia in our patient, nor did it prevent the complication in the series reported by Moore et al. 9(table 1). The soft bite block might prevent local compression of the tongue by the teeth, but cannot prevent regional venous obstruction from neck flexion. Moreover, many patients developed this complication without the use of an oropharyngeal airway (table 1). Because flexion of the neck can result in the whole spectrum of obstruction, from the absence of obstruction to complete venous obstruction, mild to moderate swelling of the tongue may occur without causing significant airway impairment. These cases may go unnoticed, let alone reported.
In summary, review of the literature and our case experiences suggest that macroglossia following posterior fossa procedures is not an infrequent complication, and is not unique to the use of the sitting position. Its etiology may be related to venous and arterial obstruction leading to reperfusion injury. The risk factors include neck flexion, obesity, local compression, and long duration. Because the onset of macroglossia may be delayed, the risk of complete airway obstruction is always present, and anesthesiologists need to be aware of this potential life-threatening complication.