The preoperative evaluation of patients undergoing tympanomastoidectomy does not differ much from other day surgery ENT cases. These are usually elective surgeries, with limited blood loss and fluid shifts. Acute mastoiditis unresponsive to intravenous antibiotics is an exception that may require urgent or emergent surgery, given the potential for complications such as facial palsy, sepsis, or intracranial infection [1].

It is important to evaluate the patient’s risk for PONV and tailor the anesthetic plan accordingly. As the patient’s head will be rotated during the procedure, it is important to establish a tolerable range of neck motion with the patient in the awake state, so as to avoid potential neck injuries resulting from patient positioning after the patient is under general anesthesia.

As best as can be predicted from the preoperative evaluation, some assessment should be made regarding the patient’s ability to safely tolerate mild/moderate decreases in blood pressure (in cases where deliberate hypotension is being considered) or the effects of epinephrine contained in the local anesthetics.

Common symptoms of ear disorders include hearing loss, vertigo, and nausea. Due to these symptoms, patients may be uncomfortable before the surgery. If the patient uses a hearing aid, efforts should be made to allow for its use for as long as possible before induction, and to replace the device(s), if possible, during emergence to facilitate communication and minimize anxiety [2].

The majority of tympanomastoidectomies are performed under general anesthesia because of the discomfort of the procedure as well as the risk of a poor outcome if the patient were to move during the case. However, these procedures can also be performed under MAC and local anesthesia, and be well-tolerated by the patient with minimum discomfort [3]. For improved success, it is necessary that the hospital, anesthesiologists and surgeons have sufficient experience performing these surgeries under sedation.

Adequate sedation and analgesia can be accomplished with different medications. Dexmedetomidine seems to be comparable to midazolam-fentanyl for sedation and analgesia in tympanoplasty [4]. Propofol can also be used for sedation in these cases [5].

It is crucial to select patients carefully for MAC. Ideally they should not be obese, not be at increased risk for aspiration, not have history of claustrophobia or panic attacks and have a reassuring airway. Patients should be made aware of what to expect during the procedure, such as operating room noise, and what would be expected from them, such as stillness and tolerance of relatively awake state. For the patient in this case example, her history of panic attacks makes the option of MAC less appealing for all involved.

Injection of lidocaine with epinephrine is performed by the surgeon at the beginning of the case. Local anesthetic injection can rarely cause transient facial nerve palsy [6]. This paralysis can be distressing for the patient under sedation, or if still present while recovering after general anesthesia.

Systemic absorption of epinephrine can produce hemodynamic instability with hypertension or cardiac arrhythmias. Anesthesiologists typically try to allow blood pressure and heart rate to return to normal levels without treatment, but a severe or acute episode may require direct vasodilator agents or alpha-antagonist as the preferred treatments.

Some issues are particularly relevant while caring for a patient undergoing middle ear surgery. These include attention to patient positioning, use of a surgical microscope requiring a bloodless surgical field, use or avoidance of nitrous oxide, implications of facial nerve monitoring and preservation, need for smooth emergence, and PONV prevention and treatment.

During surgery, the head of the surgical bed and the patient’s airway is usually turned 90 or 180° away from the anesthesiologist. Proper preparation is required in order to keep the patient safe while the table is rotated and afterwards. It is critical to adequately secure the ETT or LMA, to position the monitor cables in a way that avoid tangles and disconnections, and to have make sure the anesthesia circuit tubing and intravenous lines of sufficient length.

Also, for this surgery, the patient’s head and neck will be extended and rotated away from the surgical side, with the operative ear up. Excessive pressure in the dependent ear and eye should be avoided, as well as any extreme positions that could produce cervical nerve injury. The patients should be safely secured to the table to prevent falls, as the surgical beds are often tilted dramatically during these cases.

The surgeon operates with a microscope and while these procedures have very minimal blood loss, any bleeding appears magnified and obstructs visualization of the surgical field. Controlled hypotension is frequently used to achieve a bloodless operative field, which is needed for a successful tympanomastoidectomy. This can be achieved either using inhalational anesthetics or total intravenous anesthesia technique (TIVA).

It seems reasonable to aim for a mild to moderate (15–20%) reduction in blood pressure, avoiding any profound hypotension (MAP <60–65). Hypotension carries the risk of increased morbidity and mortality due to ischemic organ failure. A cardiovascular evaluation should consider the ability of the patient to tolerate mild hypotension, and preclude the use of controlled hypotension in certain patients who have significant carotid stenosis or coronary artery disease.

Several different agents have been used successfully to provide controlled hypotension for middle ear surgery, including clonidine [7], esmolol [8], nitroprusside [9], magnesium sulfate [10] and remifentanil. Remifentanil infusion, added to propofol or an inhaled anesthesia, is currently preferred in clinical practice, as it provides good surgical conditions without the side effects of cardiovascular hypotensive agents [11]. Remifentanil also decreases patient movement during surgery and results in a more rapid emergence at the end of the case. Dexmedetomidine could be helpful; however research regarding its use for tympanomastoidectomy is still limited [12, 13].

Regarding the choice of the inhaled agent used for maintenance of the anesthesia, sevoflurane [14], isoflurane, and desflurane [15], all enable acceptable surgical conditions and hypotension for middle ear surgeries.

The middle ear cavity is filled with air and is non-distensible. Nitrous oxide is more soluble than nitrogen in blood, as a result, when nitrous oxide is used, it can move more quickly into the middle ear than nitrogen can be displaced, potentially producing a pressure increase in the middle ear. The opposite happens once nitrous oxide is discontinued, with negative pressure in the middle ear as nitrous oxide diffuses into the blood. These mechanical effects can cause tympanic membrane rupture and interfere with maintenance of the position of graft material and/or of ossicular reconstruction prostheses.

Additionally, there are concerns about the potential for nitrous oxide causing an increase in the patient’s risk of developing PONV. Barometric changes in the middle ear produced by nitrous oxide may even be the cause for an increase in PONV in these surgeries [16].

The lack of any clear benefit derived from the use of nitrous oxide, combined with the above mentioned drawbacks, suggest avoiding it during tympanomastoidectomy; but if used, it should be discontinued at least 30 min before the tympanoplasty or ossiculoplasty in order to allow re-equilibration of the middle ear cavity.

Injury to the facial nerve is a concern during tympanomastoidectomy. Hence, facial nerve electromyography monitoring (FNM) is used during these procedures. FNM electrodes are placed into the ipsilateral orbicularis oris and orbicularis oculi muscles, with ground electrodes placed in the neck or chest.

Muscle relaxant agents are contraindicated during the maintenance of the anesthetic, as injury to the facial nerve can occur anywhere along its course and if the patient is paralyzed this injury may go unrecognized. However succinylcholine can be used to facilitate intubation during induction. Some practitioners prefer to intubate without any muscle relaxant at all; using only propofol and remifentanil. If a muscle relaxant is used during intubation, return of neuromuscular function should be verified [17] (to rule out pseudocholinesterase deficiency) before surgery can proceed. As the patient is not paralyzed, the surgeon should communicate clearly before any painful stimulation.

Remifentanil can be added to an inhaled anesthetic or TIVA with propofol to decrease the chance of patient movement. If remifentanil is used vigilance is required, as always during anesthesia. While mild controlled hypotension is adequate, profound bradycardia or severe hypotension can occur when adding remifentanil, as tympanomastoidectomy is not a very painful procedure. If bradycardia occurs, glycopyrrolate, atropine, ephedrine, or epinephrine can be given, as needed, but sometimes it may be necessary to simply discontinue the use of remifentanil.