Bilateral
Neck Exploration
The surgical approach in I HPTH patients has evolved
over the years. Bilateral neck exploration with the patient under
general anesthesia has been the gold standard surgical approach for
parathyroidectomy in both symptomatic and asymptomatic patients. This
approach requires general anesthesia and a collar incision to identify
all parathyroid tissue. Resection of obviously enlarged parathyroid
glands with or without biopsy of the remaining glands is performed
(3).
Unilateral Minimally Invasive Technique
Recently,
in selected patients with I HPTH, the surgical approach has changed
from bilateral cervical exploration to unilateral neck exploration
under local anesthesia. Patients who are candidates for the latter
approach should satisfy all the following criteria:
1.
Successful preoperative localization of a solitary parathyroid adenoma
by ultrasound and/or by Tc-99m sestamibi
2.
Absence of thyroid disease requiring surgical therapy
3.
No history of familial hyperparathyroidism or multiple endocrine
neolpasia
4.
Absence of severe psychiatric illness and deafness (3)
In
a study conducted by Udelsman et al (7) an outpatient minimally
invasive parathyroidectomy was performed on 33 consecutive patients.
He reported that the two major ingredients for the success of this
procedure are the preoperative sestamibi-single photon emission
computerized tomography (SPECT) localization and the intraoperative
assay of parathyroid hormone (PTH). All 33 patients had localization
of the adenoma by Sestamibi-SPECT as outpatients. This technique
results in three-dimensional reconstruction and allows the surgeon
to accurately predict the location of abnormal glands. In the operating
room, a superficial anterior cervical block is performed by the
operating surgeon using lidocaine with 1:100,000 epinephrine on
the side of the localized adenoma. A large bore peripheral IV line
is used to sample blood to determine intraoperative intact PTH (iPTH)
levels. After confirmation of the cervical block, intravenous sedation
is administered (Midazolam,1-3mg) and then a 1 to 4 cm incision
is made over the localized parathyroid adenoma.
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The interpretation of the iPTH is based on the comparison
of the baseline iPTH level obtained before the parathyroid excision
to that obtained 5 minutes after gland removal. If the iPTH falls
by more than 50%, indicating successful removal of the parathyroid
adenoma, the exploration is concluded. However if the iPTH does
not fall, another sample for iPTH drawn 10 minutes after removal
of the adenoma is analyzed. If no further fall in the iPTH is observed,
then the ipsilateral neck and the contralateral side are explored
for a second adenoma. Patients are converted to general anesthesia
if they were not able to tolerate exploration under local anesthesia.
Candidates for outpatient surgery were discharged quickly from the
postoperative care unit within 3 hours of surgery. Results showed
that the mean 5-minute iPTH level fell by 70% in all patients who
had iPTH assay, and the absolute 5-minute iPTH level fell by more
than 50% in 91% of the patients, indicating cure of I HPTH by resection
of a single parathyroid adenoma under local anesthesia. Of the 30
patients who had resection of single adenoma under local anesthesia,
26 (87%) were discharged within 3 hours of the procedure (7).
In
another study conducted by Udelsman et al (8), the analytical performance
of the rapid iPTH assay and its clinical performance were tested
in a series of 200 patients. The rapid assay was applied intraoperatively
to 200 consecutive cases (before and 5-10 minutes after resection
of the hypersecreting paratyroid gland) and was then compared with
results in a central laboratory (immunoradiometric assay). In the
195 patients who completed the study and had defined clinical outcomes,
the overall accuracy of iPTH assay in predicting surgical success
was 88% using the criterion of a 50% decrease at 5-10 minutes and
97% including the subset of patients with delayed decreases of PTH.
Thus the rapid PTH assay proved to have excellent analytical performance
and excellent agreement with the PTH immunoradiometric assay, and
predicted the success of parathyroid surgery in this large series
of consecutive patients.
[p.04]
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