Thursday, June 17, 2004

Notes on Endocrine Surgery : Adrenal Medula

My Dear Students,
You can down load these notes and pay more attention on understanding the problems during lecture
yours with knowledge base
Dr Arun Jamkar
THE ADRENAL GLANDS

The adrenal gland, one on each side, is enclosed, together with the kidney, within the renal fascia but a lamina of fibroareolar tissue separates the two structures, so that they occupy separate compartments.
The adrenal gland because of its anatomical position has been a fascinating area for surgeons and now with advent of minimum invasive surgery the fascination has further increased. In addition it is one of the rare field where a combined team efforts by surgeon, physician . and anesthetist have shown miracle results
The right adrenal is triangular in shape and the left is semi lunar.
Each gland has usually three arteries, but a single vein. The arteries are:
1 The Superior adrenal artery, branch of Inferior phrenic Artery
2. The Middle adrenal artery, branch of abdominal aorta direct.
3,.The Inferior adrenal artery, branch of Renal.artery
The veins on the two sides differ from each other:-
a) The right adrenal vein is very short and drains directly into the inferior vena cava, distal to the hepatic vein. The vein is so short that the gland actually sits on the inferior vena cava.
b) The left adrenal vein is longer and it drains into the left renal vein. Anatomical communications exist between the renal vein and the Azygos vein, so that the venous blood from the left adrenal has direct access into the vertebral, intercostals, and internal mammary veins of the left side.

These differences in the veins of the two sides are important in two ways:
1.Adrenalectomy is a little more difficult on the right side because the vein is so short that it may tear even with mild traction on the gland, and as the tear is practically on the inferior vena cava, the bleeding may prove very difficult to be controlled.
2) Metastatic lesions from malignant tumours of the adrenal (e.g. Neuroblastoma) may show differences in their distribution. With growths on the right side, hepatic metastasis is commoner; with tumours on the left side, bone metastasis is commoner (especially the skull, by way of vertebral veins).

The adrenal gland ( like the pituitary) consists of two different tissues , the cortex and the medulla. Except for the fact that these two parts are in so intimate anatomical relationship as to deserve description together, there is every reason to consider the two parts separately, because developmentally, structurally, as well as functionally, the two behave as separate endocrine organs.They only share blood supply and anatomical location.





THE ADRENAL MEDULLA
Embryology: The adrenal medulla is ectodermal in origin. It is developed together with the sympathetic nervous system, from the neuroectoderm. Hence, it is in close functional relationship with the sympathetic nerves, its secretions acting on the sympathetic nerve endings.Chromafin cells from neuro ectoderm migrate towards the primitive cortex and enter inside to form the medulla.

Histology:
The adrenal medulla consists of :-
The medulla is below the inner most layer of zona Reticularis .mainly chromaffin tissue, an aggregation of chromaffin cells. These are large polyhedral cells and are so named because they contain granules which stain yellow with chromic acid. These granules are actually the secretions of the adrenal medulla and they are found as such, inside the small radicals of the adrenal vein.
2)Some nerve cells of the sympathetic nervous system.

Functions: The secretion of the adrenal medulla consists of different catecholamines, of which only two are important:
1.Adrenaline.
2. Noradrenaline: This is the unmethylated precursor of adrenaline.
In health, 80% of the secretion of adrenal medulla is adrenaline and only 20% nor-adrenaline.

Adrenaline causes peripheral vasoconstriction but muscular vasodilatation.
Nor adrenaline causes an over-all vasoconstriction. However, the actions of nor-adrenaline is short lived. These effects are produced by the action of adrenaline and nor-adrenaline on the sympathetic nerve-endings. In conditions like fear, anger and pain ( i.e. when the body is subjected to noxious stimuli), the adrenal medulla is stimulated by way of the splanchnic nerve and it quickly liberates its hormones in the blood to make a rapid response . Adrenaline has an additional effect of glycogenolysis.
















TUMOURS OF THE ADRENAL MEDULLA

There are three common tumours-
Phaeochromocytoma, Ganglioneuroma and Neuroblastoma.
Classification:
A) According to Origin:
l. Those :arising from the chromaffin cells- Phaeochromocytoma.
2. Those arising from the nerve cells (mature or immature) of the sympathetic nervous system:
a) Arising from and reproducing nerve cells of very immature type-Neuroblastoma.
b) Arising from and reproducing ganglion nerve cells of adult type-Ganglioneuroma.
B)According to Pathology:
1.Benign:
a,. Ganglioneuroma
b,. Phaeochromocytoma ( 90%)
2.Malignant
a) Neuroblastoma
b) Phaeochromocytoma (10%)



PHAEOCHROMOCYTOMA
Phaeochromocytomas are tumours composed of chromafin tissue derived from nervous system ,It is a functionally active catecholamine secreting tumor.
It produces an excess of adranaline especially noradranaline 20:1 ratio
It occurs in 4th and 5th decade of life,with higher preponderance in the female
Only 0.5 % of all hypertensives have their hypertension due to pheochromocytoma
Yet all Patients with sustained hypertension under 60 years should be evaluated for Pheochromocytoma.
Origin: These tumours originate in the chromaffin cells of the adrenal medulla. 90% arises from chromafin cells in adrenal medula
10% occasions tumour may originate from extra-adrenal chromaffin tissue (i.e. at ectopic sites) e.g.
a). ) Most common extra adrenal site is Oragn of Zuckerkandle,
b) Para ganglia of sympathetic nervous system-coeliac, mesenteric,
renal, hypogastric, testicular
c) Sympathetic ganglia.
A tumour in an ectopic site is more likely to produce nor-adrenaline

• Phaeochromocytoma. Can be a part of autosomal dominant multiple endocrine neoplastic syndrome
 Multilple endocrine adenomatosis type IIB (Parathyroid adenoma/hyperplasia, Medulary carcinoma of thyroid,Phaeochromocytoma)

 Multiple endocrine adenomatosis type IIA ( Sippel’s syndrome)
Medularry carcinoma of thyroid,mucosal adenoma,Marfanoid app., Phaeo.

 Von Hippel- Lindau syndrome (Haemangioplastoma of cerebellum,retina or brain and Phaeochromocytoma.


Pathology: Pheochromocytoma is called as 10 % tumour as
10% are extra adrenergic
10% are Multiple
10% are malignant
10% are in Children
10% are Bilateral

1.The tumour is usually benign, but may be malignant (10%). Metastasis may occur from a malignant growth.
2.In about 10% of cases the tumour is bilateral. Sometimes there are multiple tumours.
3.The tumour is usually small ( less than 5 cm). It has a thin but definite capsule. It is soft and is brownish in colour.
4. Microscopically, it consists of phaeochromocytes in large numbers. these are large, well-differentiated round cells, which characteristically stain black with chromium salts.
.

Pathological Effects:
This tumour is important because it secretes the adrenal medullary hormones in excess- both adrenaline and nor-adrenaline. The proportion between the two differs from case to case, but in a vast majority it is the nor-adrenaline which preponderates. The normal ratio of adrenaline to nor adrenaline (80:20) may just be reserved. A tumour in an ectopic site and one in a child is more likely to produce nor-adrenaline These hormones, released into the blood stream, cause hypertension. In all the cases, to start with, the hypertension is paroxysmal, the systolic blood pressure rising to alarmingly high levels during the attacks. in at least 50% of the cases the hypertension becomes persistent, though paroxysms may be superadded even on such cases. As the hypertension becomes persistent all its complications may set in.

A similar type of paroxysmal hypertension may occur in the rare condition of hyperplasia of the adrenal medulla, in which both the adrenalins share.

Clinical Features: Almost always the patient is an adult, both the sexes being equally affected. The presenting features are :
1. Paroxysms of hypertension, or hypertensive attacks are very characteristics pheochromocytoma, They are predisposed by Bending, twisting,Change of
emotions and Post-prandial hypoglycemia. During the attacks there is increased catecholamines in circulation producing both alpha and beta adrenergic effects
Due to alpha adrenergic effect The systolic blood pressure is raised enormously during attacks,Tachycardia,Excessive head ache, sweating unrelated to Temperature Palpitation.Nervousness,Circumoral Pallor.
The patients during the attak are frightened , have feeling of Doom, and say “ I am going to Die” .Weakness, hypotension follows the attack which is severe enough to produce gangrene especially at periphery like Toes and fingers.

2. Other associated symptoms, which in order of frequency are – headache (35%), palpitation, vomiting,(26%) sweating (27%), dyspnoea,(19%) weakness and pallor.(17%)
Nevousness 10%. Abdominal pain 12% .Persistent hypertension in about 50% of cases. Even in these cases, attacks of paroxysmal increase may occur from time to time. Cardiovascular changes may set in, and Hypertensive retinopathy may occur.
3. Cholelithiasis
4 .Abnormal glucose tolerance test,10% of cases develop diabetes mellitus
5 Bleeding may be presentation in form of Epistaxis,Hematemesis,and Haematuria
.4. A phaeochromocytoma may originate or may be switched into activity during pregnancy.


Special Investigations:
A. Radiography;
1 .A straight X-ray may very occasionally show a soft tissue shadow in the adrenal
re gion. Usually, however, the tumour is too small to cast such a shadow.
2 I.V.P. may show displacement of the pelvi-calyceal system at the upper pole
of the kidney. This may sometimes be mistaken for a renal tumour.
3. Paracoccygeal air insufflation into the Retroperitoneal tissues:-
Due to better modalities of investigation ,this modality is no more used
B Aortography – As the tumours are usually vascular, the increased vascularity may be well demonstrated.
C Retrograde venous catheterization and injection of a contrast medium.
4. CAT Scan may be of great help in the diagnosis.

B.Hormone Tests:
1.Urine Tests:
(a)Estimation of V.M.A.( vanillyl mandelic acid), which is a metabolite of the catecholamines i.e. nor-adrenaline and adrenaline. A colorimetric examination is done. The normal output is 2 to 8 microg in 24 hours. In phaeochromocytoma this level is significantly raised.
(b)Direct estimation of catecholamines in the urine by flourimetric method. This may be done as an alternative to (a).
© Animal Test: Extracts from the patient’s urine, containing the catecholamines, are injected into a cat to find if there is arise in blood pressure.
2. Blood Examination: A retrograde venous catheterization is done and blood from the inferior vena cava is directly drawn for estimation of nor-adrenaline.
3.Pharmacological Tests: These are done by administration of drugs, which either
Provoke or diminish the hypertension, and their effects are studied:
(a)Drugs provoking hypertension: Histamine or mecholyl is injected intravenously and an attack of hypertension is provoked for confirmation of diagnosis. The procedure is dangerous for the patient, and is therefore condemned.
(b)Drugs diminishing hypertension: Adrenaline-antagonist drugs are administered and the blood pressure is reduced; this confirms the diagnosis. This procedure is safe and therefore standard. Piperoxane or dibenamine may be used, but the most commonly used drug is Rogitine (phentolamine), 5mg given intravenously.



Treatment: The only available treatment is removal of the adrenal gland on the affected side. If the side is certain, an extra-peritoneal approach by the lumbar route (as for the kidney) is done. The twelfth (sometimes also the eleventh) rib is excised to expose the adrenal. If the side of the tumour is uncertain, a transperitoneal approach has to be made, so that both the adrenals can be examined.
Surgery for Pheochromocytoma
Open Adrenalectomy
1. Lateral Retroperitoneal
2. Transabdominal
Laparoscopic Adrenalectomy
1. Retroperitoneal
2. Transpertitoneal
Intra operative Control of Catecholamine Release
Combination of regional + G.A. provides satisfactory condition till tumour exposure
During Manipulation of tumour –brisk Presser response :
1. Control of hypertension
with potent I V vasodilator eg Sodium NitroPurusoid
2. Control of Tachycardia - with Beta blockers

Special Precautions at Operation: During anaesthesia and while manipulating the adrenal, there is every possibility of rise in blood pressure to serious levels. After removal of the adrenal, with the tumour, there is again the possibility of sudden fall of blood pressure. These may be combated by the following procedures:-
1.Regitine, 20 to 40 mg thrice daily, is given orally for a few days prior to the date of operation.
(2) Before induction of anaesthesia, Regitine 5 mg is administered intravenously.
(3)While manipulating the adrenal, Regitine 5 mg is again given intravenously, and repeated if required.
(4) As soon as the adrenal gland is removed (or the vein ligated), nor-adrenaline is given intravenously to combat hypo tension. A nor-adrenaline drip may have to be continued for the first forty eight hours and then the drug is gradually tailed off over a week.

1 Comments:

Blogger Unknown said...

Piperoxan is an antihistamine drug which is derived from benzodioxan. At first it was investigated by Fourneau as an α-adrenergic-blocking agent, then they found it resistant to histamine-induced bronchospasm in guinea pigs. Piperoxane hydrochloride

October 13, 2018 at 8:52 AM  

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