2. Acromegaly

Question 1

An acromegalic patient presents for surgery to a pituitary tumour.

What are the common surgical approaches?

Answer 1

1. Transsphenoidal
2. Frontal Craniotomy

Question 2

Transsphenoidal

Answer 2

Over 90% of pituitary adenomas will be treated by the trans-sphenoidal approach.

This approach, in which an incision is made in the nasal septum,
is well tolerated and gives good cosmetic results.

Complications are uncommon but include:

Haemorrhage

Visual loss

Persistent CSF leak

Panhypopituitarism

Stroke

Question 3

How can pituitary tumours present?

Answer 3

Most pituitary tumours are benign and arise from the anterior pituitary.

They can be secreting (around 70%) or
non-secreting and may present in a number of ways:

1. Mass effect of the tumour:
2. Effects from the secretion of one or more hormones
3. Non-specific – headache, infertility, epilepsy
4. Incidental, e.g. during imaging (‘incidentalomas’)

Question 4

1. Mass effect of the tumour:

Answer 4

Headache
Nausea and vomiting
Visual field defects
Cranial nerve palsies
Papilloedema
Raised ICP (rare, but more common with non-functioning macroadenomas)

Question 5

Classification of pituitary tumours:

Answer 5

1. Non-functioning (25%)
   Commonly null-cell adenomas,
   craniopharyngiomas and meningiomas
2. Functioning (75%)

Prolactin 30%

Prolactin + GH 10–12%

GH 20%

ACTH 12–15%

FSH/LH 1–2%

TSH 1%

Question 6

What are the features of acromegaly?

Answer 6

There is hypersecretion of growth hormone with resultant soft tissue
overgrowth.

Clinical features include:

1. Face
   Increased skull size
   Prominent supraorbital ridge
   Prognathism
   Headaches
2. Mouth
   Macroglossia
   Soft tissue overgrowth in larynx/pharynx
   Obstructive sleep apnoea
3. Skeleton
   Large hands and feet
   Thick skin
   Osteoporosis
   Kyphosis
4. Neuromuscular
   RLN palsy
   Peripheral neuropathy
   Proximal myopathy
5. Cardiovascular
   Hypertension
   Heart failure
6. Endocrine
   Diabetes

Question 7

Diagnostic tests for acromegaly:

Answer 7

1. Random serum growth hormone > 10 mU/l – can give false-positives
   due to its short half-life and pulsatile pattern of release.
2. Failure of growth hormone suppression following a glucose load.
3. Elevated IGF-1 –
   growth hormone exerts many of its effects through
   insulin-like growth factor-1 (IGF-1) which also has a longer half-life
   than growth hormone.

Question 8

Which features are of concern to the anaesthetist?

Answer 8

1. Upper airway obstruction

This may result from a large mandible,
tongue and epiglottis together with
generalised mucosal hypertrophy.

Laryngeal narrowing may cause difficulty with tracheal
intubation and post-operative respiratory obstruction can
occur.

A history of stridor, hoarseness, dyspnoea or
obstructive sleep apnoea should be specifically asked for.

2. Cardiac
   Hypertension and
   congestive cardiac failure requiring
   pre-operative investigation and treatment.
3. Endocrine
   Commonly glucose intolerance and diabetes mellitus.
   Other associations include thyroid and adrenal abnormalities
   that may necessitate thyroxine and steroid replacement.

Question 9

What post-operative management problems may you encounter?

Answer 9

1. Surgical complications

2.Hormonal supplementation

3.Diabetes insipidus

4. CSF rhinorrhoea
5. Post-operative pain
6. Hypertension on emergence

Question 10

Surgical complications

Answer 10

Haemorrhage
Stroke
Visual loss
Cerebral oedema leading to impaired consciousness

Question 11

Hormonal supplementation

Answer 11

1. Steroids
   Surgery may reduce the function of the pituitary
   gland and hydrocortisone is often prescribed in the
   immediate peri-operative phase.
2. Thyroxine
   Prescribed with caution due to the risk of cardiac ischaemia.
3. Insulin
   Titrated to the required serum glucose concentration.

Question 12

Diabetes insipidus

Answer 12

This occurs in 40% of patients and is transient,

typically occurring in the first 12–24 hours
due to oedema around the surgical site.

It presents as polyuria with a
low urine osmolality despite normal/high serum osmolality.

Treatment is by estimating and replacing the fluid deficit
(which is hypo-osmolar) and the

administration of desmopressin (DDAVP), a synthetic ADH analogue.

Question 13

CSF rhinorrhoea

Answer 13

Generally, no treatment is required, although the
risk of infection is probably increased. CSF drainage
(e.g. lumbar drain) may reduce the pressure
sufficiently to allow the leak to seal.

Question 14

Hypertension on emergence

Answer 14

May contribute to post-operative bleeding but is often short-lived.

Ensure adequate analgesia.

May require short-acting agents to control such as labetalol.