Frontal Sinus Trephine
A. Simon Carney
INTRODUCTION
Because of its superficial location, the frontal sinus is perhaps the most challenging to reach endoscopically but paradoxically the easiest to reach through an external approach. Frontal sinus trephine has been used for decades to drain potentially life-threatening infections of the frontal sinus, especially prior to the discovery of antibiotics. With the emergence of endoscopic sinus surgery and in particular with the aid of technologic advances such as image navigation, malleable instruments, variable-angle endoscopes, and balloon dilation catheters, the need for frontal sinus trephination has been reduced significantly. Nevertheless, there remain circumstances when trephination of the frontal sinus not is only necessary but can actually be the simplest method of stabilizing a patient’s condition. Commercial mini-trephine kits are also used regularly as an aid during endoscopic sinus surgery. In this chapter, I will systematically discuss the contemporary indications and options for traditional frontal trephination as well as mini-trephine, highlighting circumstances when the surgeon can use both trephination options in conjunction with other endoscopic techniques for more challenging situations.
HISTORY
A thorough rhinologic history should be obtained for all patients in whom a frontal trephine is being contemplated. A typical presenting history might include frontal headache and pain, tenderness to the touch, or even meningeal signs. In some situations, the patient may actually be unconscious as a result of intracranial complications of sinusitis, as a result of medical complications of immune deficiency, or following traumatic injury. In these cases, a history from a relative or witness may be the only option. In patients with unresolving acute frontal sinusitis, it is particularly important to ask about any history of trauma, previous sinus surgery, any other external approaches, and in particular where the conditions such as a mucocele, a malignant process, or inverting papilloma had been treated previously.
Medical conditions such as diabetes, immune deficiency, and ongoing chemotherapy for other malignancies should also be identified. Bleeding diathesis and a history of the use of any medications such as aspirin, clopidogrel, heparin, and warfarin as well as nonsteroidal anti-inflammatory agents should also be obtained. If there are any extrasinus complications such as swelling, diplopia, reduction in vision, or a reduced Glasgow Coma Scale, the time frame and history of these should be carefully elicited and documented.
PHYSICAL EXAMINATION
Before examining the nasal cavity, the patient should be examined externally. By examining the patient from behind, with the head tilted back, subtle swelling or asymmetry of the orbits may become apparent. Any supraorbital edema or swelling should be evaluated for fluctuation. The orbital rims should be palpated to establish if there are any areas of dehiscence in the frontal bones. The supraorbital foramina are usually palpable just
above the medial end of the eyebrow—these are important landmarks for some forms of frontal trephination. The eyes should be examined for diplopia as well as color vision and visual acuity. In the absence of any symptoms or signs, a formal ophthalmologic opinion is not required although if the orbit is compromised, it is essential that an urgent ophthalmologic consult is obtained. Anterior rhinoscopy and nasal endoscopy following decongestion of the mucosa are essential parts of the investigation. Any adhesions or altered anatomy from previous surgery should be documented. The eye should be ballotted to establish any dehiscence in the lamina papyracea. The presence and origin of any mucopurulent secretions should be documented, and an endoscopically obtained sample should be obtained for microbiologic culture.
above the medial end of the eyebrow—these are important landmarks for some forms of frontal trephination. The eyes should be examined for diplopia as well as color vision and visual acuity. In the absence of any symptoms or signs, a formal ophthalmologic opinion is not required although if the orbit is compromised, it is essential that an urgent ophthalmologic consult is obtained. Anterior rhinoscopy and nasal endoscopy following decongestion of the mucosa are essential parts of the investigation. Any adhesions or altered anatomy from previous surgery should be documented. The eye should be ballotted to establish any dehiscence in the lamina papyracea. The presence and origin of any mucopurulent secretions should be documented, and an endoscopically obtained sample should be obtained for microbiologic culture.
INDICATIONS
Acute frontal sinusitis resistant to adequate medical therapy with complicating factors that would make an endoscopic approach undesirable (e.g., lack of surgical experience, bleeding diathesis, or poor medical condition)
The need for a microbiologic sample in a patient with immunodeficiency in whom formal transfer to the operating room for an endoscopic approach would be contraindicated
For endoscopic visualization of the lateral portion of the frontal sinus (e.g., to assess the presence or absence of recurrent tumor)
For biopsy of a lesion in the mid- or lateral portions of the frontal sinus, which cannot be accessed via endoscopic approaches
Administration of fluorescein as a guide during endoscopic sinus surgery (mini-trephine)
For access during combined endoscopic and open approaches to the frontal recess
For retrograde ballooning of the frontal recess
For routine postoperative irrigation of the frontal sinus to avoid instrumentation of the frontal recess
CONTRAINDICATIONS
The absence of a frontal sinus or severely hypoplastic sinus
Dehiscence of the posterior wall of the frontal sinus (relative contraindication)
Fracture of the posterior wall of the frontal sinus with ongoing CSF leak
Massive Kuhn type IV cell replacing most of the frontal sinus
Overlying cutaneous abnormality (e.g., cavernous hemangioma)
PREOPERATIVE PLANNING
CT Scanning: A good-quality triplane CT scan of the sinuses is essential before embarking on a trephine of the frontal sinus. The CT DICOM images may be downloaded onto image navigation equipment to facilitate placement of the frontal trephine. The CT scan should be closely reviewed to assess the degree of pneumatization of the frontal sinus and the presence of any Kuhn cells into which the trephine may inadvertently be placed. The continuity of the frontal sinus should be ascertained, and the presence of any fractures or areas of dehiscence should be carefully noted.
MRI Scanning: A gadolinium-enhanced MRI scan may be indicated where there is suspicion of a benign or malignant tumor occupying the frontal sinus. In patients with a renal transplant, the contrast agent may be contraindicated. Likewise, an MRI will not be possible in patients with magnetic foreign bodies or severe claustrophobia. In the vast majority of cases, the MRI scan will be able to distinguish the presence of purulent exudate, mucus, or tumor. If both fluid and tumor are present within the frontal sinus, it is preferable to place the frontal trephine in an area where seeding of the tumor will not occur (i.e., into the fluid-filled part of the sinus rather than that occupied by tumor).
Blood Tests: Although not routinely required, in some cases, a coagulation screen may be desirable. In severely ill patients, a complete blood count and full electrolyte and glucose measurements will usually have been obtained by the medical team.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
