Anesthesia management for Pituitary tumor

Dr. Abhijit Nair,

Axon Anesthesia Associates,

Consultant Anesthesiologist,

Care Hospital,

Hyderabad.

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Pituitary adenomas are common, 1 in 1000

Benign

Slow growing, but can invade adjacent

structures ( cavernous sinus )

Carcinomas : RARE

Mechanism of tumor generation:

Malfunction of growth regulating genes

Abnormalities of tumor suppressor genes

Alteration in genes controlling programmed cell death

Risk factors for developing pituitary tumors:

MEN 1

Carney complex

Isolated familial

Acromegaly

Pituitary Gland:Master Endocrine Gland

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.

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

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

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

By site of origin :

Sellar ( tumors of anterior & posterior pituitary)

Suprasellar ( craniopharyngioma, suprasellar extension of pituitary lesion )

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

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 conditionsPituitary apoplexy ( rarely )

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

Important factors:Experience of Surgeon

Size & location of tumor

Consistency of tumor

Other variables

( vascularity, presence of

venous sinuses )

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 )

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

Pre operative assessment:

:-Visual function

:-Signs and symptoms

of raised ICP

:-Endocrine studies,

effects of hormonal

hypersecretion

:-Co morbidities

- in acromegaly ,

Cushing’s syndrome

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%

:- OSA

:- Hypertension

:- Glucose intolerance

AcromegalyIncreased 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

Cushing’s syndrome

Appearance

Impaired Glucose tolerance

Hypertension, ECG changes,

LVH, ASH

Hypernatremia, hypokalemia, alkalosis

OSA, GERD

Proximal myopathy

Cannulation

Surgical approach:

Trans sphenoidal approach

- Sublabial

- Endonasal

Trans ethmoidal approach

Trans cranial

- Subfrontal

- Pterional

Anesthetic management

Hemodynamic stability

Maintenance of cerebral

oxygenation

Facilitate surgical conditions

Prevent of intra operative

complications

Rapid emergence to facilitate

early neurological assessment

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.

Cont:

Throat pack

Preparation of nasal mucosa

Lumbar drain ( in patients with significant suprasellar extension )

Position

Maintenance:“ Personal preference”

Any technique suitable for intracranial procedures

Extra cautious in presence of raised ICP

Short acting agents

Normocapnia

RAE tube south

Monitoring:

Standard

ABP

Filling pressures

( Cushing’s disease )

VEP ( Visual evoked potential )

PNS

Emergence from anesthesiaSmooth and rapid

Removal of pack, pharyngeal suction

Extubation in a semi seated position

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 )

Post op care:

Airway management

Analgesia

Hormone replacement

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

Treatment

DDAVP (desmopressin acetate ) nasal/ sc

s/c Vasopressin

Monitor plasma sodium, osmolality

IVF ( maintenance + 2/3rd urine output in previous hour )

Type of fluid ( on electrolyte picture)

Hyponatremia

Commonest cause: over enthusiastic DDAVP use

Rarely- SIADH

In SIADH : water retention,

Loss of sodium in urine

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

THANK YOU