Pheochromocytoma
Definition
Pheochromocytoma are tumours arising from neuroectodermal cells of the adrenal medulla or extra adrenal sites they are found increased frequency in patients with hypertension MEN2a and MEN2b syndrome and von recklimghausen,s nerurofibromatosis
Peak incidence
Is th 4 th and 5 the decade
The rule of tens applied to pheochromocytoma
as 10% are bilateral
10% extra adrenal
10% familial
10% multicentric
10% malignant
Occurs in children 10%
The triad of headaches , papitations and diaphoresis should arouse the suspicion of a pheochromocytoma
Other significant symptoms include hypertension headache postural hypotension and tremors
Diagnosis
Is confirmed by a 24 - hour urine collection for VMA , metanephrine and catecholaminas with noradrenaline having the best sensitivity and VMA the best specificity for pheochromocytoma CT , MRI and MIBG are the imaging modalities used
CT has been shown to have a sensitivity of 85-90%and a specificity of 70-100%
MIBG is similar to noradrenaline in structure and hence taken up by adrenergic tissue . MIBG scanning provides useful functional data on these tumours
Treatment
Is by adrenalectomy which can be performed by a midline subcostal or transabdominal approach . alternatively laparoscopy may be used if the disease is benign
Specific preoperative problems relating to surgery of pheochromocytomas
Include massive hypertensive surge during tumour handling . hypotensive shock following tumour devascularization and hypoglycaemia
A week,s preoperative treatment with long acting alpha blocker phenoxybenzamine combined with a beta blocker if tachycardia develops has reduced the operative mortality by controlling the catecholamine surge
metyrosine (tyrosine hydroxlase antagonist ) is also occasionally used preoperative
general anaesthetic induction is using inhaled gases as isofurane to minimalize cardiac depressant effects
adequate volume repletion is necessary as often these patients are underfilled due to to the increased vasoconstrictive state
Definition
Pheochromocytoma are tumours arising from neuroectodermal cells of the adrenal medulla or extra adrenal sites they are found increased frequency in patients with hypertension MEN2a and MEN2b syndrome and von recklimghausen,s nerurofibromatosis
Peak incidence
Is th 4 th and 5 the decade
The rule of tens applied to pheochromocytoma
as 10% are bilateral
10% extra adrenal
10% familial
10% multicentric
10% malignant
Occurs in children 10%
The triad of headaches , papitations and diaphoresis should arouse the suspicion of a pheochromocytoma
Other significant symptoms include hypertension headache postural hypotension and tremors
Diagnosis
Is confirmed by a 24 - hour urine collection for VMA , metanephrine and catecholaminas with noradrenaline having the best sensitivity and VMA the best specificity for pheochromocytoma CT , MRI and MIBG are the imaging modalities used
CT has been shown to have a sensitivity of 85-90%and a specificity of 70-100%
MIBG is similar to noradrenaline in structure and hence taken up by adrenergic tissue . MIBG scanning provides useful functional data on these tumours
Treatment
Is by adrenalectomy which can be performed by a midline subcostal or transabdominal approach . alternatively laparoscopy may be used if the disease is benign
Specific preoperative problems relating to surgery of pheochromocytomas
Include massive hypertensive surge during tumour handling . hypotensive shock following tumour devascularization and hypoglycaemia
A week,s preoperative treatment with long acting alpha blocker phenoxybenzamine combined with a beta blocker if tachycardia develops has reduced the operative mortality by controlling the catecholamine surge
metyrosine (tyrosine hydroxlase antagonist ) is also occasionally used preoperative
general anaesthetic induction is using inhaled gases as isofurane to minimalize cardiac depressant effects
adequate volume repletion is necessary as often these patients are underfilled due to to the increased vasoconstrictive state
.jpg)
.jpg)
0 comment:
Post a Comment