Ch45 Pituitary adenomas - Surgical management, outcome and recurrences Flashcards
(25 cards)
When should stress doses be given to patients with pituitary adenomas?
During and immediately after surgery
How should you reverse hypothyroidism pre-operatively?
Check HPA axis. Replace cortisol before T4. Replace T4 for >4 weeks prior to surgery ideally
When is a transcranial pituitary resection required over a transphenoidal?
When there is extrasellar extension into the middle fossa or residual inaccessible tumour following transphenoidal surgery
What are the transcranial routes to the pituitary?
Subfrontal - prechiasmal (better if chiasm post-fixed) Pterional - optico-carotid triangle
Anatomy of the subfrontal route to the pituitary gland
How do manage carotid injury during TSPH?
Signalled by profuse arterial bleeding
Pack off with surgicel/muslin
Inform anaesthetist
Stop operation
DSA to identify a pseudoaneurysm
Steps of a TSPH
Supine / Mayfield / Neuronavigation
Elevate head 15 deg
Prep thigh for fat graft
C-arm lateral fluoro if not using neuronav
Direct (endoscopic) or Indirect (microscopic) approach to sphenoid
Midline opening of sella with drill and expand with rongeur (avoid opening into carotid)
X-opening of dura with #11 scalpel
Use ring cureetes to deliver tumour and remove with rongeur/aspirate
Deliver suprasellar component with valsalva or injecting saline into lumbar drain
After debulk of tumour dissect margins
How do you perform a TSPH for Cushing’s disease without lesion on MRI?
Paramedian incision and exploration on the side with highest ACTH on IPSS. If negative then paramedian incision on the contralateral side then a midline incision. If no tumoru can eb identified then perform a hemihypophysectomy on the sied with highest ACTH.
Note adenomas are usually soft purple/gray whilst the normal fland is pink and firm.
How do you close the sella defect after TSPH?
Fat graft
Fascial covering
Gasket closure with implant or septal cartilage
Fibrin glue
Nasoseptal flap
Where is the sphenoid ostium?
At the back of the middle turbinate
What hormonal complications may occur after TSPH?
DI (triple phase response = DI 24 hours, normalisation / siADH, DI long-term)
Addisonian crisis
Long-term hypopituitarism (TSH/ACTH/FSH/LH deficiency)
What is secondary empty sella syndrome?
The chiasm retracts into the evacuated sella causing visual impairment
Where is the blood supply to the chiasm?
From the ophthalmic A and sup. hypophyseal A which lie below the chiasm. Disrupting this whilst removing tumour may worsen vision.
What are the post-operative consideration following TSPH?
- Fluid balance - perform urine specific gravity, serum and urine osmos and repeat Na daily or if the UO>250ml/h for 2 hours
- Antibiotics until removal of nasal packs on day 3-6
- Stress steroid administration
**Do not allow drinking through a straw to avoid negative pressure causing a CSF leak
How do you manage DI post TSPH?
Replace losses PO or IV
If losses >400 ml/h x2 hours then send serum/urine osmolarities, urine SG and Na. If urine SG <1.003 then consider Desmopressin but be cautious about the triple-phase response.
Why does the DI triple phase response occur?
Transient DI following surgery 12-36 hours due to post. pituitary injury
Normalisation / SIADH picture due to release of cells once they die
Long-term DI as no more cells to produce the ADH
How do you manage steroid dosing post-TSPH?
Continue stress dosing for 48 hours. Stop the hydrocortisone for 24 hours then measure morning serum cortisol.
If morning cortisol >9 mcg/dl then normal.
If <9 mcg/dl then restart hydrocortisone and refer to endocrinology for assessment of ACTH reserve by undertaking short-synacthen test at 1 month. Note: in ACTH deficiency there is adrenal atrophy and becomes unresponsive to the synacthen so will not peak at >18 mcg/dl which is a normal response.
What is the metyrapone test?
This is performed to assess the pituitary ACTH reserve. A synacthen test should be performed first to rule out primary adrenal insufficiency.
Metyrapone is an 11b-hydroxylase inhibitor and reduces cortisol production and subsequently increases upstream metabolites such as 11-Deoxycortisol.
Given 2-3 gram at midnight and measure serum 11-Deoxycortisol in the morning. If there is limited ACTH reserve the adrenals will be atrophied and the total 11-Deoxycortisol levels will be low.
What are the action sites of medical therapies for Cushing’s disease?
Metyrapone inhibits 11-beta-hydroxylase
Ketaconazole inhibits 17-alpha-hydroxylase
Mitotane and etomidate inhibit desmolase
How do you assess cure for GH secreting tumours?
Oral glucose tolerance test (GH levels should suppress to <1ng/ml if cured).
What are the outcomes for TSPH in acromegaly?
85% cure with adenomas <10 mm
(50% overall).
Patients not cured require life-long medical therapy. The greater the debulk the better the response to medical therapy!
What is the definition of cure with Cushing’s disease?
<50 mcg/l (but may be too stringent!)
If >50 then re-exploration may be advised.
Low dose Dexamethasone test is predictive of remission following surgery.
If you stop the steroids for 24 hours then 24-hour urinary free cortisol is helpful in determining cure rates/
What treatment is given to residual adenomas secreting TSH?
Radiation
How do you monitor patients following TSPH?
MRI
Endocrine follow up at day 2, 6 weeks and 12 months and Na on day 2 and 7
Opthalmology f/u
