You obtain a computed tomography (CT) scan (Fig. 12.2) after having referred your patient to your otolaryngology colleague. The endocrinology workup reveals no abnormalities. The ophthalmologist confirms your examination findings. The patient wants to have this lesion treated.

You elect to proceed with a transnasal transsphenoidal approach to resect this tumor. Your otolaryngology colleague helps with the exposure. After opening the dura, you notice that the mass behind the dura appears firm and yellowish. You send a small biopsy piece to pathology for a frozen section and you are told that this may be meningioma, normal pituitary, or adenoma. The pathologist is not able to give you an exact diagnosis based on frozen section.

    You then elect to remove whatever portion can be safely removed, without applying any tension on the carotid arteries or the diaphragm sella. However, you notice a small opening in the right cavernous sinus that you pack with fibrin glue at the end of the case. You also do notice a cerebrospinal fluid (CSF) fistula at the end of your resection.

    You were able to achieve ~80–90% resection. You were also able to remove the suprasellar portion of the mass.

You left behind a part that abuts the carotid arteries directly.

The patient develops transient diabetes insipidus (DI) postoperatively that lasts ~4 days. After having received desmopressin acetate (DDAVP; 3 doses), her sodium levels drop from 150 meq/L to the upper 120s mEq/L within 72 hours. However, her mental status remains stable. You watch her another few days and the sodium and urine output normalize.

    She develops a partial oculomotor nerve palsy on the right side, 2 weeks postoperatively. You obtain a CT scan (Fig. 12.3). You are unable to obtain an MRI as the patient had a pacemaker placed prior to her surgery. She has an elevated white blood cell (WBC) count (20,000–25,000) and no fever. A lumbar puncture (LP) reveals 0 WBC and no organisms.

    After discharge, she presents 4 days later with headaches, nausea, increasing urine output, hypotension, and sodium level of 143 mEq/L.

• Endocrinologic signs and symptoms need to be evaluated as the tumor may cause compression of the stalk or may be actively secreting a certain pituitary hormone, most commonly prolactin. Ask for weight gain or loss, lacrimation, changes in menstrual cycle, peripheral edema, mood swings, temperature fluctuations, sweats, chills, etc. Look for signs of acromegaly, edema, etc.
  
• An endocrine laboratory panel consisting of serum prolactin, luteinizing hormone, follicle-stimulating hormone, thyroid-stimulating hormone, adrenocorticotropic hormone, AM cortisol, growth hormone, and insulin-like growth factor-1.1,2
  
• Evaluate thoroughly all cranial nerves, particularly the optic, oculomotor, trigeminal, trochlear, and abducens as they are in proximity to the mass.
  
• Endocrine and ophthalmology consultations should be sought.

• Pituitary adenoma
  
• Meningioma (tuberculum sella, diaphragma sella)
  
• Other (less likely) diagnoses: Mnemonic is “SATCHMO.”¹
  
  
  
  • Sarcoid, sarcoma
    
  • Aneurysms
    
  • Teratoma
    
  • Craniopharyngioma, cyst (Rathke), carcinoma
    
  • Hamartoma
    
  • Metastases
    
  • Optic glioma

• Documented tumor growth
  
• Symptomatic mass: visual or endocrinologic symptoms
  
• Compression of the optic chiasm

• Transsphenoidal approach is preferred in this case as the tumor is accessible via this route. The suprasellar portion of the mass appears to be small and easily resectable. If it does not displace inferiorly during the initial approach, a staged procedure may be done. Alternatively, an extended transsphenoidal approach may be attempted with unroofing of the sphenoid sinus.³
  
• Other approaches also include
  
  
  
  • Craniotomy with pterional or subfrontal approach³
    
  • Endoscopic endonasal approach⁴

• Preoperative preparation⁵
  
  
  
  • Place a lumbar drain preoperatively.
    
  • Harvest a fat graft from the abdomen or right thigh.
    
  • Have some fibrin glue available intraoperatively.
  
  
• Intraoperative care
  
  
  
  • Avoid excessive pulling on the diaphragm sella during resection.
    
  • Use intraoperative C-arm radiographic guidance and possibly stereotactic frameless navigation to evaluate the anatomy of the sella and its posterior and superior borders.
    
  • Microscope magnification
    
  • May also use an endoscope
    
  • Pack the sella with layered fat graft and fibrin glue; you may also place a small piece of cartilage of bone harvested during the approach to close the posterior wall of the sphenoid sinus.⁵
  
  
• Postoperatively
  
  
  
  • Keep the lumbar drain at 10–15 mL/h drainage for ~72 hours.
    
  • Keep the head of bed elevated at ~30 degrees at all times.
    
  • Caution the patient to avoid nose blowing, sucking through a straw, sneezing, or straining.
    
  • Frequently monitor for CSF rhinorrhea postoperatively.
    
  • If the leak persists, the patient may need further packing via intranasal approach with otolaryngologic assistance. Alternatively, you may elect to proceed with a bicoronal craniotomy with laying a vascularized periosteal flap over the sella.⁶

• As 80–90% resection was achieved, one may elect to observe the mass with serial scans and monitor for recurrence.
  
• An alternative is to treat the residual or recurrence with stereotactic radiosurgery.⁷ However, there may be a significant risk of radiation injury to the optic nerves or chiasm by using this modality.

• The patient most likely sustained a triphasic response of DI.⁸ Initially, the vasopressin releasing is halted due to the direct trauma of surgery. After a few days, the vasopressin-releasing cells that were traumatized die off, causing a surge of serum arginine vasopressin and a clinical picture of syndrome of inappropriate antidiuretic hormone. After a few days to weeks, once the surge subsides, the patient will then be in permanent DI requiring vasopressin replacement.
  
• Of note is that the diagnosis of DI does not necessarily require an elevated serum sodium level. In this case, the level was normal; however, the diagnosis was made based on the elevated urine output of >300 mL/h, low urine specific gravity (<1.005) and urine osmolality (150), in the face of normal serum osmolality (280).9
  
• Initially, give DDAVP intravenously 1–2 µg every day until the DI resolves and her condition is stabilized. Then you may switch to an intranasal route.

• Possible causes include¹⁰
  
  
  
  • Inflammatory response: This is the most likely cause, as the cavernous sinus was entered intraoperatively on the right side.
    
  • Infection such as meningitis (less likely given the normal LP findings and no other systemic symptoms – the elevated WBC count may be due to steroid replacement or postoperative response).
    
  • Local trauma (fracture of surrounding orbital bone, direct trauma to the nerve, excessive packing of the sella): also less likely due to the delay in presentation.
    
  • Vascular/hemorrhagic: The CT scan does not show any intracranial hemorrhage. Nevertheless, there might still be a small hematoma within the cavernous sinus that is too small to be visualized with CT. Alternatively, there may be an arteriovenous fistula that formed at the level of the intracavernous carotid artery.
  
  
• Management¹⁰
  
  
  
  • Start steroids (high dose initially, then taper) for suspected inflammatory response.
    
  • May continue with antibiotic coverage if infection is not completely ruled out. Use antibiotics with good CSF penetration such as a third- or fourthgeneration cephalosporin and vancomycin.
    
  • May further investigate with computed tomographic angiography (CTA) or angiography if the condition does not improve after a few days, to rule out other vascular causes.¹⁰
    
  • Obtain ophthalmology consultation to document deficit and progress accurately.