David Black PA-C

Pituitary Function

a)      Analogous to a household thermometer. The thermometer constantly measures the temperature in the house, and sends signals to the heater to turn off or on to maintain s steady, comfortable temperature. The pituitary gland constantly monitors body functions and sends signals to organs and glands to turn on or off to maintain an appropriate environment.

b)      The pituitary in controlled by the hypothalamus, which sits just above the pituitary sella.

c)      Pituitary releases GH, TSH, ACTH, FSH, LH, MSH, and endorphins.

Pituitary Tumor

d)      Arise from the anterior pituitary gland, (80% of the gland)

i)        Pituitary tumors represent ~10-15% of all intracranial tumors

ii)       Most commonly present in 30’s & 40’s

iii)     Both sexes effected equally

iv)     Usually benign

e)     Microadenoma - <1 cm diameter

i)        50% of Pituitary tumors are <0.5 cm at diagnosis, making them difficult to find at surgery

f)      Macroadenoma - >1 cm diameter

Clinical Presentation

g)     Endocrine disturbance (functional secreting)

i)       Prolactinoma

(1)  Most common secretory adenoma

(2)  Amenorrhea-glactorrhea syndrome in women, impotence in men. Often infertility and bone density loss.

ii)    ACTH – Cushing’s Disease

iii)  Growth Hormone – Acromegaly

(1)  skeletal overgrowth deformities (increased hand and foot size, thickened heal pad, frontal bossing, prognathism, macroglossa), HTN, soft tissue swelling, peripheral nerve entrapment syndromes, debilitating headache, excessive perspiration. 25% have enlarged thyroid glands with normal thyroid studies.

h)     Mass Effect

i)       Visual deficits.

(1)  bitemporal hemianopsia due to compression of optic chiasm.

(2)  decreased visual acuity

ii)    Pituitary gland

(1)  varying degrees of hypopituitarianism

(a)  hypothyroid, hypoadrenalism, hypogonadism, DI, hyperprolactinemia

iii)  Cavernous Sinus

(1)  pressure on cranial nerves contained within (III, IV, V1, V2, VI).

(a)  Ptosis, facial pain, diplopia

(2)  Sinus thrombosis

(a)  Proptosis

(b)  Chemosis

(3)  Encasement of Carotid artery

Surgical Treatment

i)       Transphenoidal Resection

i)       Extra-arachoid approach, no external scar, no brain retraction

ii)    Post-op complications

(1)  hormone imbalance

(a)  Cortisol deficiency

(i)    Generally placed on replacement hydrocortisone

(b)  Transient alterations in ADH – Diabetes Insipidus

(2)  Secondary Empty Sella Syndrome

(a)  Optic Chiasm retracts into the now-empty sella, causing visual impairment

(3)  Hydrocephalus

(a)  Due to traction on the attached third ventricle, cerebral edema due to Vasopressin release intra-operatively, or tumor edema

(4)   Infection

(a)  Pituitary Abscess

(b)  Meningitis

(5)  CSF Rhinorrhea

(a)  3.5% incidence

(b)  Usually self limiting

(c)  May require CSF diversion (lumbar drain)

(6)  Headache/Face Pain

iii)     Post-op orders

(1)   I&O’s q 1 hour

(2)   Urine Sp Grav q 4 hours and whenever urine output is >250 cc/hr

(3)   Serum Na’s q 6 hrs

(4)   Endocrinology consult

(5)   HOB to 30’

(6)   Ice chips – to avoid aspiration of fat graft, patient is NOT to use a straw or do ISB.

(7)   Antibiotics – no

(8)   Hydrocortisone replacement

(9)   Nasal packs removed POD #2

(10)                       Bi-PAP

(11)                       Generally discharge POD #2

(12)                       Post-op scan usually not required

(13)                       Diabetes Insipidus

j)        Usually transient, lasting 3-6 days post-op.

k)      Occasionally "prolonged," lasting weeks

l)       Triphasic Response: rare.

i)       Presents as DI for few days, then SIADH-like picture, then back into DI again.

m)    Diagnosis – all three criteria must be met for diagnosis

i)        Urine output >250 cc/hr for at least 2 consecutive hours

ii)    ii. Serum Na >150

iii)  iii. Urine specific gravity <1.005

n)      Treatment

i)        Fluid Replacements

ii)    DDAVP (desmopressin)1-4 mcg q 12 hours

(1)  when packs out, may use intranasally

iii)  Vasopressin 5 units q 6 hours

Outcome

o)      Significant improvement of visual symptoms immediately

p)      Incidence of recurrence is 12% within 4-8 years post-op

q)      85% biochemical cure in microadenoma (<1 cm).

r)       Only ~30% of functional macroadenomas have surgical cure.

i)       i. Very few that extend suprasellar obtain surgical cure

ii)    These tend to recur

Post-op Nursing Concerns

s)      Monitor for DI

i)       It is important to accurately measure urine outputs, spec grav’s, and send q 6 hour Na’s.

t)        Breathing

i)       difficult with packs in.

ii)    Occasionally bi-PAP – Usually use face cup with humidified O2 (keeps packs moist)

u)      Packs

i)        Removed POD #2 (by us)

ii)    Needs – kidney basin, suture removal kit, NSS whipettes

iii)  NSS nasal spray, Neosynephrine Nasal Spray

v)      Nasal Bleeding

i)       Hold pressure when packs out for 15 minutes

ii)    Do not blow nose for 48 hours

w)    CSF Rhinorrhea

i)        Means that there is a connection between the subarachnoid space and the nasal cavity. Risk of Meningitis

ii)       Salty taste in mouth, feeling of PND, clear fluid from nose

iii)     HOB to 45’

iv)  May need CSF diversion (lumbar drain) for few days

x)     Continue Antibiotics

y)      Pain

i)        MSO4, Percocet

ii)       Ice pack to face

iii)     Neosynephrine Nasal Spray