Transsphenoidal surgery

Endoscopic > microscopic

Advantages

Visualisation is better, especially within tumour bed.

Disadvantages:

Most neurosurgeons have less facility with endoscopes compared to ENT surgeons.
Lack of 3D visualisation (may be overcome using 3D endoscopes).
Need for single-handed technique (may be overcome by having assistant hold endoscope, or using an endoscope holder e.g. Mitaka)
Need for a binasal approach if it is desired to use two hands for the actual surgery.

Either endoscopic or microscopic approach is acceptable; however, after microscopic approach it is recommended that an endoscope be used at the time of the same surgery to visualise additional resectable tumour.

Children issues (youngest patient Mr Sinna has ever operated is 2 yrs old)

Sphenoid sinus non pneumatized → need CT preop to properly plan
Septum is not large enough to recreate floor of sella so need fascia lata
Smaller spaces

Endoscopic

Intra-op

Approaches

Transsphenoidal:

Pros

An extra-arachnoid approach,
No brain retraction,
No external scar (aside from where a fat graft is procured, if used).

Usually the procedure of choice.
Mono vs binasal operation
Indication

Microadenomas,
Macroadenomas without significant extension laterally beyond the confines of the sella turcica,
Patients with CSF rhinorrhea,
Tumors with extension into sphenoid air sinus

To reach the sphenoid can use

Sublabial incision or
Trans-nares: an alotomy may be used to enlarge the exposure through the nares if necessary.

Transethmoidal approach

Transcranial approaches:

Indications:

Minimal enlargement of the sella with a large suprasellar mass, especially if the diaphragma sellae is tightly constricting the tumor (producing a “cottage loaf” tumor) and the suprasellar component is causing chiasmal compression.

Extrasellar extension into the middle fossa that is larger than the intrasellar component
Unrelated pathology may complicate a transsphenoidal approach: rare, e.g. a parasellar aneurysm
Unusually fibrous tumor that could not be completely removed on a previous transsphenoidal approach
Recurrent tumor following a previous transsphenoidal resection

Choices of approach

Subfrontal:

Provides access to both optic nerves.
May be more difficult in patients with prefixed chiasm

Frontotemporal (pterional):

Places optic nerve and sometimes carotid artery in line of vision of tumor.
There is also incomplete access to intrasellar contents.
Good access for tumors with significant unilateral extrasellar extension

Subtemporal: usually not a viable choice.

Poor visualization of optic nerve/chiasm and carotid.
Does not allow total removal of intrasellar component

Technique

Position:

Supine, horseshoe head rest or (especially if image-guided navigation is used) pin headholder
Equipment:

Image-guided navigation system
Endoscopy cart for cases performed endoscopically (surgeon preference)
Microscope (if used)

Instrumentation:

Transsphenoidal instrument set (usually includes speculum, curettes, long instruments including bipolars)

Some surgeons use ENT to perform the approach and closure and for follow-up

Disasters

Usually related to loss of landmarks. Can be minimized using intraoperative navigation or fluoroscopy to verify location.

Too Lateral: injury of carotid artery:

Typically injured in lateral aspect of opening.
Bone may be dehiscent over the ICA
Signalled by profuse arterial bleeding
Can usually be packed off with

Fat/fascia graft from thigh or abdomen or
Woven Surgicel®

The operation is halted, and a STAT post-op arteriogram must be done
If a pseudoaneurysm or site of injury is identified angiographically,

Must be eliminated before a potentially lethal hemorrhage;
By

Endovascular techniques
Surgical trapping with clips above and below

Injury of basilar artery: with pulling on tissue adherent to the artery or reaching through sella and rongeuring

Too posterior: opening through the clivus and erroneous biopsy of the pons

Too anterior: opening through the floor of the frontal fossa with injury to the olfactory nerves and entry into inferior frontal lobes

Procedure

Lumbar drain:

For macroadenomas to inject fluid in order to help bring the tumor down
For post-op CSF drainage following transsphenoidal repair of CSF fistula

Medications: intraoperatively 100mg hydrocortisone IV q 8 hrs

Positioning

Elevate thorax 10–15°: reduces venous pressure
Head stabilization:

Mayfield headholder for image guidance
Horseshoe headrest

For head band with image guidance
For no image guidance

Position option 1:

Surgeon standing to right of patient
Shoulder-roll
Top of head canted slightly to left
Neck position:

For microscope: extend neck slightly with the head in either a Mayfield head-holder or on a horseshoe headrest.
For endoscope: do not extend neck (more comfortable for holding instruments)

ET tube positioned down and to patient’s left (to get it out of the way)
Microscope: observer’s eyepiece on the left

Position option 2:

Surgeon standing above patient’s head: head pointing straight up towards ceiling, neck slightly extended

Abdomen or right thigh is prepped for fat graft

C-arm fluoro: used when no navigation is used

Orient the C-arm for a true lateral by aligning the mandibular rami and/or by superimposing the floor of the left and right frontal fossae.
If this proves difficult, lay a Penfield 4 on the nasion oriented from lateral canthus to lateral canthus, then aim the fluoro to shoot “down the barrel” of the Penfield 4
To make sure you are not in the ant cranial fossas

After approach to floor of sella is complete, outline the upper and lower boundaries of the sella using image navigation or for fluoro using an instrument (e.g. suction tip)—obtain hard-copy of images for documentation purposes

Opening the sellar floor:

Starting the opening:

Picking off the thinned the bone (due to macroadenomas) or
Use a bayoneted chisel or high-speed diamond burr to start the opening

Open exactly in the midline using the nasal septum as a landmark

NB: the septum of the sphenoid sinus is unreliable as a midline indicator, and often curves inferiorly towards one of the carotid arteries.

Use a Kerrison rongeur to expand the opening.
CAUTION: stay away from the extreme lateral sella to avoid entering the cavernous sinus or injuring the carotid artery

Coagulate the dura centrally in an “X” pattern (NOT “ + ” pattern) with bipolar cautery.

Macroadenomas may cause yellowish discoloration of the dura directly over the tumour

Consider aspirating through dura with a 20 gauge spinal needle to R/O

Large venous sinus (dura often has bluish discoloration),
Aneurysm, or
Empty sella

Incise the dura in the “X” pattern in the midline with a #11 scalpel on a bayonetted handle

Tumour removal for

Macroadenoma:

Debulk the tumour

Gently bring tumour into the field with ring curettes, and remove with pituitary rongeurs or aspirate with suction.

Some tumours are very fibrous and may be difficult to remove

Do not pull on the lateral component of the tumour with pituitary rongeur due to risk of injuring carotid artery
If the suprasellar component will not come down, it may be brought down by having the anaesthesiologist inject 5ml aliquots of saline into a lumbar drain while monitoring blood pressure and pulse

Once the tumour is debulked internally, try to develop a plane between the tumour capsule and the pituitary.

Start inferiorly where the dura can be separated from the tumour capsule and then followed on the surface. Sometimes the tumour capsule cannot be removed due to severe bleeding

If complete tumour removal is often not possible, and the goal of the surgery then is “containment”
Endoscopic techniques and image-guided navigation may be employed to assist in removal of macroadenomas

Microadenoma

If the side of the tumour is known, begin exploration of the gland on that side by making incision with #11 blade and using a dissector to try and locate the tumour (like a “grain of rice in a blueberry”)
For Cushing’s disease,

If no tumour is identified on pre-op MRI

Intraoperative ultrasound may help localize tumour in ≈ 70% of cases (a specialized U/S probe is required)
If IPS sampling showed a lateralizing ACTH gradient:

Start with ipsilateral paramedian incision → contralateral paramedian → midline incisions to explore the gland until tumour is found

If IPS sampling and MRI do not suggest tumour location:

The gland is explored sequentially with 2 paramedian incisions and then a midline incision

If the adenoma still cannot be found,

Hemi-hypophysectomy is performed

On the side of higher ACTH levels if IPS sampling shows a lateralizing gradient, or
On the side with more suspicious tissue on frozen section.

Total hypophysectomy is not routinely performed

Macroscopic

Most adenomas are purplish-Gray and easily aspirated; however, some may be more fibrous.
The normal pituitary gland is firm and rubbery (the adenohypophysis is orange-pink, the neurohypophysis is a whitish-Gray), and normally does not curette very easily

Use image guidance or fluoro to determine approximate location of diaphragm sellae. Do not go cephalad to this to avoid a CSF leak, to avoid entering the circular venous sinus in the dura here, and to avoid trauma to the optic chiasm

After removal of macroadenoma, check depth of tumour bed on fluoro or image guidance, and make sure it correlates with approximate tumour volume on MRI

The sella may be packed in a number of ways, one method:

If CSF leak occurs:

Place muscle or fat in defect within sella.
Some recommend against the use of muscle because it always putrefies.
Do not overpack to avoid recreating mass effect with the graft

Recreate the floor of the Sella using nasal cartilage placed within the Sella. Alternatively, a nonporous Medpor® polyethylene transsphenoidal sellar implant may be used
If CSF leak occurs pack sphenoid sinus with fat from abdomen (option: fat with fascia on surface)
Fibrin glue may optionally be used to help hold any of these components in place

Consent

Ask about

previous nasal surgery
Type of occupation
Female and pregnancy age
Long term olfactory dysfunction

Removal of pituitary tumor through the nose, possible placement of fat graft from abdomen

Alternatives:

Surgery through the skull (trans-cranial)
Radiation

Complications:

CSF leak with possible meningitis,
Problems with pituitary hormones which may sometimes be permanent (which would require lifetime replacement therapy),
Injury to optic nerve with visual loss,
Injury to carotid artery with possible bleeding and/or stroke

Work up

Careful medical history, previous growth pattern and physical examination

Current height, weight, surface area, pubertal staging and bone age

Accurate fluid intake and output record

Paired early morning plasma and urine osmolalities

Serum urea, creatinine, electrolytes and glucose

Thyroid function (thyroxine and thyrotropin)

Hypothyroidism: hypothyroid patients should have > 4 weeks of replacement to reverse hypothyroidism but most patients tolerate surgery even with hypothyrodism; however:

Do not replace thyroid hormone until the adrenal axis is assessed;

Giving thyroid replacement to a patient with hypoadrenalism can precipitate adrenal crisis.
If hypoadrenal, begin cortisol replacement first, may begin thyroid hormone replacement after 24 hours of cortisol

Cortisol at 9 a.m. (if patient is not receiving steroids)

Prolactin (to exclude prolactinoma)

α-Fetoprotein and β-hCG (to exclude secreting germinoma)

Insulin-like growth factor-1

Pre-op

Polysporin® ointment (PSO) applied in both nostrils the night before surgery

Antibiotics: Midnight & 6 AM

Steroids

Pre-op: hydrocortisone 100mg PO at Midnight & IV at 6 AM
Intra-op: continue 100mg hydrocortisone IV q 8 hrs

Endoscopic technique

Approaches

Planning

Joint case with ENT or solo?
Complex septations of sphenoid
Non-pneumatised sphenoid
May need septoplasty, turbinate resection, anterior ethmoidectomy
Avoiding difficulties with nasoseptal flap
Unilateral ‘Cross-court’ approach for laterally placed micro adenoma
Previous naso-septal flap/revision surgery

Haemostasis

Head up, more so with Cushing’s
Normotensive anaesthesia
Nasal prep with Moffat’s solution (1ml 1:1000 adrenaline, 1ml 10% cocaine, NaBic)
Don’t traumatise mucosa
Bipolar coagulation
Warm saline irrigation
Haemostatic products

Surgicel
Gelfoam
Floseal
Surgiflo

Glasgow technique (Mr. Hassan)

Moffat solution

Supine, Head neurtal but bed in semi sitting position

Place the camera on the upper end of the nose and the instruments near the floor. Use the nose to pivot

Push the middle turbinate laterally and deflate it

Localize the conchae

Superior the conchae is the location of the sphenoidal meatus

Remove the mucosa covering the meatus.

Use kerrisons to widen the meatus to incoorporate the contraleteral meatus

Widen until you are medial to the carotids on brain lab and superor enough to touch the anterior cranial floor and inferior enough to touch the sellar floor.

Make small opening off the sellar anterior wall.

Use a double ended dissector to dissec the pituitary tumour away from bone.

Use Kerrisons to widen the opening superior, inferior and laterally (watch out for the carotids)

Use the looped curate to remove the tumour

Send sample off

Suction off the tumour

Notes

Watch out for olfactory mucosa it is a bit yellow in colour
Keep sphenopalatine artery safe as it supplies the septum mucosa (graft)
Types of sphenoid anatomy 3 types

Sphenoid Septations often go towards the carotid artery

Medial clinoid process = medial OCR. Sometimes (rhoton) is linked backwards if you pull the OCR out it can lacerate the carotid artery
Doppler is good to figure out where carotid is

Oxford technique

Planning

Patient positioning, depends on pathology
Mono vs Binasal
Middle Turbinate sparing vs resection
Mucosal sparing vs resection / coagulation
Nasal mucosal flap vs free flap / no flap
Position of surgeon / screens / assistant
Lumbar drainage CSF
Donor site for fascia / fat
Navigation
Microdoppler
Curved irrigating Drill / sonopet

Preference

Nasal prep with Moffat's solution (Iml 1:1000 Adrenaline, Iml 10%, cocaine, NaBic)
Antibiotics or Induction (Co-Amox)
Throat Pack
Binasal approach
Zero and 30 degree endoscopes - No holding arm
Middle Turbinate sparing
Mucosal sparing
No flap routinely (rescue mucosal incision)
Position of surgeon / 2 screens / assistant4 hands
No routine lumbar drainage CSF
Abdominal fat only if needed, fascia for extended
Navigation for revision / extended cases
Microdropper most cases
Drill for micro adenoma / extended

Outcomes

Knop’s classification

Chances of complete excision

Vision: Mortini 2005

Normalization of visual defects: 40.5%
Improved visual defects: 51.2%

Biochemical:

Over all initial hormonal remission: 66.1%
Prolactinomas: 25% cure
Acromegaly:

Definition of biochem cure (not standardized)

IGF-1 levels within age-matched reference range
Basal (morning) serum GH level < 5 ng/ml, AND GH nadir < 1 ng/ml in OGST

Outcome

85% cure for

Adenomas <10mm
No local invasion
Preop random GH <40ng/ml

50% cure overall for all transsphenoidal surgery
30% for macroadenomas

If not cured will require life long meds for suppression
Monitored every 6 months for recurrence

Cushing disease

Define biochem cure

Early remission:

Lowest cortisol level ≤ 140nmol/L (≤ 5 mcg/dl)
97% (31/32) patients with early remission had sustained remission with mean follow-up of 32 months
Only 12.5% (1/8) without early remission showed evidence of sustained remission
This has been used to select patients for possible early re-exploration
Early ACTH levels usually drop, but do not consistently become subnormal and are not reliable in predicting sustained remission

Later remission testing:

Conducted 3 days to 2 weeks post-op following 24 hours of steroid cessation after initial post-op coverage with glucocorticoids
24-hour urinary free cortisol
Serum cortisol: the criteria of a cortisol level <50 nmol/l (< 1.8 mcg/dl) is probably too stringent
Serum ACTH

Overnight low-dose dexamethasone suppression test:

An AM cortisol level on post-op day 3
If ≤ 8 mcg/dl after an overnight 1mg dexamethasone suppression test is predictive of sustained remission in 97%

Over all remission rate

64–93% in patients with non-invasive microadenomas in MRI
Resolution of symptoms

HTN and hyperglycaemia: within ≈ 1 year
Osteoporosis related to CD: over ≈ 2 years
Psychiatric symptoms

Thyrotropin (TSH)-secreting adenomas

Following debulking, small amounts of residual tumor may continue to produce sufficient TSH for hyperthyroidism to persist.
Following surgery + XRT, only ≈ 40% achieve a cure
Cure definition

No residual tumour at surgery or on imaging, and normal free T3 with TSH levels at or below normal.

Recurrence incidence:

≈ 12%, with most recurring 4–8 years post-op

Complication

Hormonal imbalance:

Acute post-op concerns:

Alterations in ADH: transient abnormalities are common

See typical post-op patterns (p.774) – including DI.
DI lasting > 3 months is uncommon

Cortisol deficiency → hypocortisolism → Addisonian crisis if severe

Long-term:

Hypopituitarism (5%)

TSH deficiency → hypothyroidism → (rarely) myxoedema coma if severe
Adrenal insufficiency
Deficiency of sex hormones → hypogonadotropic hypogonadism

Secondary empty sella syndrome

Chiasm retracts into evacuated sella → visual impairment
Hence need to pack sella

Hydrocephalus → coma:

May follow removal of tumours with suprasellar extension (transsphenoidally or transcranially).
Consider ventriculostomy placement if hydrocephalus is present (even if not symptomatic).
Possible aetiologies:

Traction on the attached 3rd ventricle
Cerebral enema due to vasopressin release from manipulation of the pituitary and/or stalk
Tumour enema following resection

Infection

Pituitary abscess
Meningitis

CSF rhinorrhoea: 3.5%

RCT Pittsburgh

High volume CSF leak: dec. CSF leak with lumbar drain
Low volume CSF leak:

Investigation

CT head

Done initially to exclude

Development of postoperative hydrocephalus
Subdural hematoma formation from intracranial hypotension due to CSF leak.

Management

Conservative treatment

Bed rest with head of bed elevation and lumbar drainage of CSF for 5-10 days.
Risk ranging from 7% to 30% of ascending meningitis.
70% chance of spontaenorus resolution
Don’t give prophylactic abx

As it doesn’t reduce risk of meningitis

Surgical Endoscopic Repair

Antibiotic

Recommended for 24-48 h.
To cover possible contamination at the time of surgery in a non-sterile field with concomitant sealing of the sterile to non-sterile flushing of an active leak.

A reconstructive ladder should be used to help determine the type of repair performed.

Simple, small (less than 1 cm) defects

A fat plug harvested from the earlobe or abdomen can be used to plug the defect.
The next option includes a simple overlay graft harvested from the nasal floor mucosa, turbinate mucosa, or nasal septum.

If a more complex, larger reconstruction

A composite (underlay and overlay) graft can be used consisting of an intracranial underlay of bone or cartilage from nasal septum, auricular cartilage or turbinate bone, and an overlay graft of mucosa (free or pedicled) as above.
Local pedicled flaps should include the nasoseptal flap, which is supplied by the posterior nasal septal artery, a terminal branch of the sphenopalatine artery.
Additional grafts that can be useful in larger defects include temporal fascia or tensor fascia lata grafts. These grafts are often bolstered in the sinonasal cavity with abdominal fat, a nasoseptal flap or both.

In complex situations of extensive defects or poor local tissue, such as in chemoradiated patients, a craniotomy with pericranial flap or free flap reconstruction of the skull base may be necessary.

Outcome

High success rates of

Primary repair around 90%,
Secondary repair around 97%.

These success rates compare favorably to traditional craniotomy approaches with reported success rates between 70% and 80% that carry a higher morbidity profile.

Carotid artery injury: rare

Acute: intraoperatively
Anterior aspect of the carotid siphon most commonly damaged area
Delayed:

Day 10 post-op
Breakdown of fibrin around carotid, or possibly due to rupture of a pseudoaneurysm created at surgery

Entry into cavernous sinus with possible injury of any structure within
Nasal septal perforation

Mortality: 0.3% Mortini 2005

Post-Op

Manage in ICU or ITU

No nose blowing 6wks

No flying

Cushing patients will feel worse post op if not mean you didn’t remove enough tumour

Nose bleeding

Nasal complication

Bleeding
Crusting
Infection
Anosmia

In/output charts:

Hourly documentation
Urine specific gravity (SG) 4°
Anytime urine output (UO) >250 ml/hr

Activity: BR with HOB @ 30°

Diet:

Ice chips PRN
Patient is not to drink through a straw (to avoid negative pressure on sphenoid sinus with risk of promoting CSF fistula)

IV Fluid:

Normal saline with KCL @ 100 ml/hr + excess UO
Watch out post-op diuresis

Meds

Antibiotics: continue antibiotics until nasal packing is removed
Steroids (some surgeons routinely use post-op steroids until the adequacy of endogenous steroids is established, especially with Cushing’s disease, see below).

POD0/1: hydrocortisone 50mg IM/IV QDS → POD2 prednisone 5mg PO QDS → POD3 5mg PO BD → wean to stop over POD #6
Physiologic dose= 20mg hydrocortisone a day

Labs:

Renal profile with osmolarity TDS
8 A.M. serum cortisol

Some do 6hrly post op cortisol to check if it is low, if it is then give steroid

Central Diabetes Insipidus (CDI)

Remove nasal packs on post-op day 3–6

Assessment of postoperative

ACTH (corticotropin) reserve

Patient at home: taper HC over 2–3 weeks down to 20mg PO q AM and 10mg q 4 PM (a little higher than maintenance to provide for some stress coverage) for several days
Hold the PM dose and check an 8 AM serum cortisol the next day
To avoid adrenal insufficiency in patients with incompetent reserve: as soon as the blood is drawn have the patient take their morning cortisol dose and resume regular dosing until the test results are available
If this 8 AM cortisol shows any significant adrenal function, then taper the patient off HC

Thyroid

FT4 and TSH should be assessed on day 3 or day 4 and thyroid hormone replacement should be considered if deficient.
If FT4 and TSH normal further assessment should take place at 4-8 weeks.

Discontinuation of steroids post-op

Some surgeons do not routinely assess ACTH reserve post-op for patients that were not hypocortisolemic pre-op.
Taper and stop hydrocortisone 24-48 hrs post op → check serum cortisol level 24 hrs stopping hydrocortisone
If any concerns with reserves d/c home with Hydrocortisone 50mg PO AM and 25mg PO PM
Interpretation of 6 AM cortisol levels:

6 AM cortisol	9 am cortisol	Interpretation	Management
≥ 9 mcg/dl	> 550 nmol/L	Normal	No further tests or treatment
3–9 mcg/dl	400-550 nmol/L	Possible ACTH deficiency	Place patient on hydrocortisone¹
≤ 3 mcg/dl	< 400 nmol/L	ACTH deficient	Place patient on hydrocortisone¹

¹perform cosyntropin stimulation test 1 month post-op; D/C steroids if normal; if subnormal, then permanent replacement required

Imaging post op

Best time was 4 months post op.

Because the max height of the pituitary mass did not return to normal until then