This document discusses anesthesia management for pituitary tumor surgery. Pituitary adenomas are common benign tumors that can invade surrounding structures. Risk factors include genetic conditions. Pre-operative evaluation assesses hormonal levels and effects, as well as comorbidities related to hormonal hypersecretion like acromegaly and Cushing's syndrome. Anesthetic management aims to maintain hemodynamic stability, cerebral oxygenation, and facilitate surgery while preventing complications. Special considerations include potential airway difficulties and post-operative hormone replacement or complications such as diabetes insipidus or hyponatremia.

1. Anesthesia management for Pituitary tumor Dr. Abhijit Nair, Axon Anesthesia Associates, Consultant Anesthesiologist, Care Hospital, Hyderabad. i

2. Pituitary adenomas are common, 1 in 1000 Benign Slow growing, but can invade adjacent structures ( cavernous sinus ) Carcinomas : RARE

3. Mechanism of tumor generation: Malfunction of growth regulating genes Abnormalities of tumor suppressor genes Alteration in genes controlling programmed cell death

4. Risk factors for developing pituitary tumors: MEN 1 Carney complex Isolated familial Acromegaly

5. Pituitary Gland: Master Endocrine Gland

6. Cont: 2 histological entities- Large, vascular, pink anterior lobe or adeno hypophysis Small, grey-white posterior lobe or neuro hypophysis Stats : 6mm height, 13 mm width, 9mm AP.

7. Cont. Lies within pituitary fossa or sella turcica Floor & anterior wall of sella – Roof of sphenoid sinus Posterior wall – clivus Lateral wall – cavernous sinus Roof – Diaphragmatic sella

8. Type of Adenoma Secretion Pathology Corticotrophic ACTH,POMC Cushing’s syndrome Somatotrophic GH Acromegaly Thyrotrophic ( Rare ) TSH Hyperthyroidism (asymptomatic) Gonadotrophic LH,FSH Asymptomatic Lactotrophic or Prolactinomas ( most common) Prolactin Galactorrhoea,hypogonadism, amenorrhoea, impotence, infertility Null cell adenomas No secretion

9. Classification: By nature: 1) Benign, 2) Invasive adenomas, 3) Carcinomas By activity: 1) Non functioning, 2) functioning By size: 1) Micro adenoma, < 1cm, 2) Macro adenoma, > 1cm

10. By site of origin : Sellar ( tumors of anterior & posterior pituitary) Suprasellar ( craniopharyngioma, suprasellar extension of pituitary lesion )

11. History: Pierre Marie, a French neurologist in Paris was the first to describe disease involving pituitary gland In 1886, he studied patients with clinical findings of what he termed as acromegaly & postulated that pituitary gland was the culprit

12. Presentation: Hormonal hyper secretion syndromes: Hyperprolactinaemia,acromegaly,Cushing’s disease Mass effect: visual disturbance or raised ICP Non specific: infertility, headache, epilepsy, pituitary hypofunction Incidental: Detected during imaging for other conditions Pituitary apoplexy ( rarely )

13. Goals of pituitary surgery: To remove as much as tumor as possible to relieve compression & to eliminate hormonally active tissue Avoid additional neurological damage To protect healthy pituitary tissue

14. Important factors: Experience of Surgeon Size & location of tumor Consistency of tumor Other variables ( vascularity, presence of venous sinuses )

15. Work up: Basal prolactin concentration, ( 2.8-29.2 ng/ml in women, 2.1-17.7 ng/ml in males) Growth hormone: GH concentration: short t1/2, misleading if done alone- abnormal if > 10 mU/L ) Failure of GH suppression to < 2mU/L with 75 gm oral glucose, Increased IGF-1 ( a somatomedin )

16. ACTH: Primary screening procedures- - Urinary concentration of free cortisol, - Loss of diurnal cortisol control, - Lack of response to ACTH suppression Thyroid function tests, High quality MRI, CT scan – for bony invasions

17. Pre operative assessment: :-Visual function :-Signs and symptoms of raised ICP :-Endocrine studies, effects of hormonal hypersecretion :-Co morbidities - in acromegaly , Cushing’s syndrome

18. Anesthetic issues : Anatomical changes: Prognathism and macroglossia thickening of the pharyngeal and laryngeal soft tissues and vocal cords reduction in the size of laryngeal aperture hypertrophy of periepiglottic folds Recurrent laryngeal nerve palsy enlarged thyroid: 25%

19. :- OSA :- Hypertension :- Glucose intolerance

20. Acromegaly Increased skull size, enlarged lower jaw Mal occlusion of teeth Macroglossia, prognathism, thickened pharyngeal & laryngeal tissues Hypertension, Cardiomegaly Impaired LV function Impaired Glucose tolerance Proximal myopathy, difficult cannulation Enlarged thyroid

21. Cushing’s syndrome Appearance Impaired Glucose tolerance Hypertension, ECG changes, LVH, ASH Hypernatremia, hypokalemia, alkalosis OSA, GERD Proximal myopathy Cannulation

22. Surgical approach: Trans sphenoidal approach - Sublabial - Endonasal Trans ethmoidal approach Trans cranial - Subfrontal - Pterional

24. Anesthetic management Hemodynamic stability Maintenance of cerebral oxygenation Facilitate surgical conditions Prevent of intra operative complications Rapid emergence to facilitate early neurological assessment

25. Cont: Airway management: 4 grades described in acromegaly:- Grade 1 – No significant involvement Grade 2 – Nasal & pharyngeal mucosal hypertrophy with normal glottis Grade 3 – Glottic stenosis or VC paresis Grade 4 – Glottic & soft tissue abnormalities South wick JP, Katz J. Unusual airway obstruction in acromegalic patients- indications for Tracheostomy. Anesthesiology 1979; 51: 72-3.

26. Cont: Throat pack Preparation of nasal mucosa Lumbar drain ( in patients with significant suprasellar extension ) Position

27. Maintenance: “ Personal preference ” Any technique suitable for intracranial procedures Extra cautious in presence of raised ICP Short acting agents Normocapnia RAE tube south

28. Monitoring: Standard ABP Filling pressures ( Cushing’s disease ) VEP ( Visual evoked potential ) PNS

29. Emergence from anesthesia Smooth and rapid Removal of pack, pharyngeal suction Extubation in a semi seated position

30. Operative complications: False aneurysm ( Rx: endovascular / clipping ) Damage to pons ( minimised by frequent fluoroscopy ) In transcranial: Frontal lobe ischemia- prolonged traction Seizures ( subfrontal ) Anosmia ( olfactory tract damage )

31. Post op care: Airway management Analgesia Hormone replacement

32. Post op hormone complications: Diabetes insipidus : Develops within first 24 hrs ( when > 80% vasopressin secreting neurons are destroyed or become non functional ) Features :- Increased Posm > 295 mosm/kg Hypotonic urine ( < 300 mosm/kg ) Urine output > 2ml/kg/hr consistently

33. Treatment DDAVP (desmopressin acetate ) nasal/ sc s/c Vasopressin Monitor plasma sodium, osmolality IVF ( maintenance + 2/3 rd urine output in previous hour ) Type of fluid ( on electrolyte picture)

34. Hyponatremia Commonest cause: over enthusiastic DDAVP use Rarely- SIADH In SIADH : water retention, Loss of sodium in urine

35. References: Pituitary disease & Anesthesia. M Smith & N P Hirsch. BJA 85(1) : 3-14(2000) Treatment of Pituitary tumors : a surgical perspective. Chandler, Barkan. Endocrinal Metab Clin A Am, 37(2008) 51-66 Barash’s Clinical Anesthesia Miller’s Anesthesia Harrison’s Principles of Internal Medicine Google Web & Images

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