Transcript Surgical approaches and Landmarks

Surgical Anatomy
Thyroid and Parathyroid Glands
Bastaninejad Shahin
MD, ORL&HNS, TUMS, Amiralam Hospital
Presentation outlines
• Thyroid Gland:
– General measures
– Vascular supply
– Important proximities
– Surgical approaches and important Landmarks
• Parathyroid glands:
– General measures
– Surgical localization
Thyroid Gland
General measures
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Two lateral lobes connected with isthmus
Total weight is about 15 to 25 g
Each lobe: 4 x 1.5 x 2cm (height/width/depth)
Extends from C5 to T1 vertebra
Isthmus is over 2nd & 3rd tracheal ring
Approximately 40% of patients have a
pyramidal lobe that arises from either lobe
or the midline isthmus
40% present
General measures...
• Cervical Fascia:
– True Thyroid Capsule
– Surgical Capsule
– Berry’s Ligament (connecting the lobes of the
thyroid to the cricoid cartilage and the first two
tracheal rings)
• Surgical Approaches regarding to the Fascia:
– Intracapsular Thyroidectomy
– Extracapsular Thyroidectomy
Berry’s Ligament
Vascular Supply
• Two pairs of arteries
• Three pairs of veins
• Connecting vessels within the thyroid true
capsule
• In less than 10%, there is a midline arterial
supply to the gland, named as Thyroid Ima
artery
Important proximities
 About 12cm
 About 5-6cm
Non-recurrent LN, Less than 1%
Can be find in
only 10-30% of
the times
1 cm
Surgical approaches and Landmarks
• The course of the inferior laryngeal nerve
is highly variant
• Incidence of nerve paralysis is three to
four times greater in cases in which the
recurrent nerve was not localized
compared with cases in which it was
• Try to seek, expose and identifying the
nerve, instead of avoiding it!
• Extracapsular approach with nerve
identification is the method of choice
The most common
course of
Incidence is
the nerve ismore
within
TEinGroove
higher
Revision cases
(48.5% - not depicted
here)
42.2%
5.4%
3.9%
Extralaryngeal Branching (35.5% in some reports up to 80%!)
Surgical approaches and Landmarks
• Lateral Approach
– Inferior Thyroidal Artery
– Tubercle of Zuckerkandl (ZT)
• Inferior Approach
– Lore’s triangle
– Tracheoesophageal Groove
• Superior Approach
– Posterolateral aspect of the Cricoid
– Berry’s ligament
– Inferior border of the inferior Constrictor
– Inferior horn of the thyroid cartilage
...Lateral Approach
• Used most commonly
• RLN is identified typically at the thyroid
midpole level (less nerve dissection
required)
• This approach is less useful for Revision
ZT is Present
in 63-80% of
the patients
...Inferior Approach
• Used for Revision cases and Goiter
surgery (not substernal)
• Problem: Longer nerve dissection and
probability of Parathyroid glands ischemia
• Benefit: nerve will be find before any
extralaryngeal branching
...Superior Approach
• Used for large substernal Goiters
• Nerve is at the lower edge of the lateral
aspect of the cricoid cartilage
• Nerve should be identified just caudal to
the lowest fibers of the inferior constrictor
Parathyroid Glands
General measures
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Two pairs: Superior and Inferior
Weight is about 50 to 70 mg
Size 5 x 3 x 1 mm
Color of normal parathyroid glands ranges
from yellowish brown to reddish brown
• 87% there are four glands (super numerary glands
are usually in the mediastinum or thymus gland)
• Their Arterial supply is usually from Inferior
Thyroid artery (80%)
Surgical Localization
• Superior Parathyroid Glands
– 80% they are at the cricothyroid junction
approximately 1 cm cranial to the
juxtaposition of the recurrent laryngeal
nerve and the inferior thyroid artery.
– Ectopic glands: it cloud be intrathyroid,
paraesophageal, retroesophageal and
mediastinal
(posterior
superior
compartment)
...Surgical Localization
• Inferior Parathyroid Glands:
– More variable location
– More than 50% of the inferior parathyroid
glands are situated near the lower pole of the
thyroid gland
– Ectopic glands: it could be situated in
thyrothymic ligament (28%) or mediastinum
(Anterior superior compartment)