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Trigeminal Nerve
Block
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The trigeminal nerve
consists of three divisions: the ophthalmic nerve (V1), maxillary
nerve (V2), and mandibular nerve (V3). These three branches supply
sensation to most of the face, excluding the angle of the jaw, which
is supplied by the second cranial nerve. Trigeminal nerve blocks
are used mainly to treat severe pain from trigeminal neuralgia and
various malignancies affecting the face.
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The gasserian or
trigeminal ganglion lies within the medial cranial fossa across
the superior border of the petrous temporal bone. The posterior
two thirds is fully covered by dura matter. This posterior portion
lies within a small recess called Meckel’s cave. This invagination
of the dura surrounding the posterior two thirds of the ganglion
allows direct continuity with the cerebrospinal fluid.
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Used for intractable
pain from trigeminal neuralgia (tic douloureux) or cancer after
conservative treatments have failed. This type of block is recommended
when more than one division of the trigeminal nerve is involved.
Neurolytic solutions (alcohol, glycerol) and radiofrequency rhizotomy
techniques are also used for more permanent blockade or destruction
of the nerve.
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The major complication
is corneal anesthesia leading to loss of sensation and corneal ulcers.
Subarachnoid injection can cause unconsciousness or seizures.
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Mandibular Nerve
Block
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The largest of the
three divisions is the third division, the mandibular nerve that
exits the cranium through the foramen ovale. Below the foramen the
mandibular nerve divides into a smaller anterior and larger posterior
division. The anterior division innervates the muscles of mastication
(lateral pterygoid, temporalis, and masseter muscles). The posterior
division is mainly sensory, dividing into the inferior alveolar,
lingual, and auricotemporal nerves. The mandibular nerve is both
a sensory and motor nerve.
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Trigeminal neuralgia,
malignant conditions involving the lower jaw (e.g., Ewing’s
sarcoma, osteogenic sarcoma) or cancer of the tongue.
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Neuritis if nerve
is traumatized or bleeding into the cheek.
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Maxillary Nerve
Block
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After leaving the
gasserian ganglion, the maxillary nerve passes along the inferior
lateral border of the cavernous sinus. It then exits the middle
cranial fossa through the foramen rotundum and enters the pterygopalatine
fossa, where it divides into its major branches. The maxillary nerve
is a sensory nerve.
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Trigeminal neuralgia,
malignancy, or radiation damage to middle third of the face, nasal
cavity, and hard palate.
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Bleeding due to
highly vascular pterygopalatine fossa. Injections using greater
the 1 mL of volume can spread into the orbit and thus affect the
oculomotor and abducens nerves, resulting in visual difficulty.
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Glossopharyngeal
Nerve Block
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The glossopharyngeal
nerve exits the skull through the jugular foramen located posterior
to the tip of the mastoid process. The nerve then passes anteriorly
between the internal jugular vein and internal carotid artery, coursing
medial to the styloid process and lateral to the vagus and spinal accessory
nerves. The glossopharyngeal nerve supplies sensation to the posterior
one third of the tongue, the palatine tonsils, and pharyngeal wall.
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Glossopharyngeal
neuralgia characterized by pain of the throat with possible radiation
to the ear and thyroid cartilage area and pharyngeal cancer.
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Dysphagia from
paralysis of the pharyngeal muscles and weakness or partial paresis
of the tongue. The block should only be performed unilaterally since
a bilateral block will produce complete paralysis of the pharyngeal
muscles. Weakness in the trapezius muscle can also be seen due to
blockade of the spinal accessory nerve.
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Occipital Nerve
Block
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The greater occipital
nerve is formed from the dorsal primary ramus of the second and
third cervical nerves. It supplies sensation to the medial-posterior
portion of the scalp. This nerve is usually located 2 to 3 cm lateral
to the external occipital protuberance and just medial to the occipital artery,
which serves as a reliable landmark. The lesser occipital nerve
arises from the ventral primary ramus to the second and third cervical
nerves passing along the posterior border of the sternocleidomastoid
muscle. It is located approximately 2.5 cm lateral to the occipital
artery.
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Blocking the greater
and lesser occipital nerves can be used for diagnostic or therapeutic
measures in managing patients with suspected occipital neuralgia
or occipital headaches.
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Generally none.
Possible seizure if large amount of local anesthetic injected into
occipital artery.
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Upper Extemity:
Shoulder
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Brachial Plexus
Block
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The brachial plexus
is formed from the ventral primary rami of the fifth (C5), sixth
(C6), seventh (C7), and eighth (C8) cervical nerves along with
the first thoracic nerve (T1). The C4 and T2 spinal nerves may also
contribute to the plexus. These roots pass between the anterior
and middle scalene muscles in the neck before passing into the arm.
After dividing into upper, middle, and lower trunks, these nerves
enter the axilla between the clavicle and first rib. The trunks
then divide into anterior and posterior divisions, which in turn
divide into lateral, medial, and posterior cords. Within the axilla,
near the lateral border of the axilla, the cords divide into the
peripheral nerves of the upper extremity.
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- Long thoracic nerve contains fibers from C5, C6, and
C7.
- Suprascapular nerve contains fibers from C4, C5, and C6.
- Peripheral branches of the lateral cord form the musculocutaneous
nerve and lateral root of the median nerve formed from C5, C6, and
C7.
- Peripheral branches of the medial cord (C8 and T1) form
the medial root of the median nerve, the ulnar nerve, and the medial
cutaneous branches of the arm and forearm.
- Peripheral branches of the posterior cord form the axillary,
radial, and subscapular nerves.
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There are four
approaches to blocking the nerves of the brachial plexus. The interscalene,
supraclavicular, and infraclavicular approach will provide anesthesia
for the entire arm including the shoulder. The axillary approach
can be used for anesthesia between the hand and elbow. Continuous
infusions of local anesthetic through a catheter can also be used
for prolonged block of the various peripheral nerves of the brachial
plexus. Indications for brachial plexus block include:
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- Anesthesia for upper extremity surgery
- Postoperative pain relief and rehabilitation
- Differentiate sympathetic pain from peripheral nerve injury
- Manipulation of frozen shoulder or wrist injuries
- Continuous sympathetic nerve blockade to improve blood flow
to the affected extremity (i.e., Raynaud’s)
- Phantom limb pain
- Differentiate pain of peripheral neuralgia verses a more
central origin (i.e., brachial plexus avulsion).
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For interscalene
approach: epidural or intrathecal injection, inadvertent vertebral
artery or intravenous injection, and recurrent laryngeal and phrenic
nerve block.
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For supraclavicular approach: phrenic nerve block, cervical
sympathetic block, and 0.5% to 6.0% incidence
of pneumothorax.
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For axillary approach: intravascular injection with seizure incidence
1.5% and axillary artery damage.
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Suprascapular
Nerve Block
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Arises from C4, C5,
and C6 contributions from the upper trunk of the brachial plexus.
It passes beneath the trapezius muscle to the superior border of
the scapula, where it passes through the suprascapular notch. The
suprascapular nerve is the major sensory supply to the shoulder
joint and motor supply to the supraspinatus and infraspinatus muscles.
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Used to treat arthritis
or bursitis of the shoulder joint in addition to intra- and periarticular
injections. Diagnostically, to confirm suprascaplular nerve irritation
or entrapment.
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Paralysis of the
supraspinatus and infraspinatus muscles.
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Pneumothorax from
the needle being advanced past the upper border of the scapula.
Direct nerve injury.
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Upper Extremity:
Elbow and Wrist
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The median nerve,
formed from the lateral and median roots of the brachial plexus,
contains fiber from C5 through T1. There are no branches in the
upper arm and it descends with the brachial artery being slightly
medial to it at the elbow. It crosses the elbow anteriorly and passes
between the two heads of the pronator teres. It courses through
the wrist deep to the palmoris longus tendon.
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Used to supplement
a brachial plexus block or as diagnostic and therapeutic block and
the elbow or wrist (i.e., carpal tunnel).
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Technique and Landmarks
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Medial
and lateral epicondyles of the humerus and medial to the brachial
artery.
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The ulnar nerve is
formed from the C7, C8, and T1 roots. At the elbow, it lies behind
the medial epicondyle in the ulnar groove.
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Used to supplement
brachial plexus anesthesia or as diagnostic and therapeutic block
for ulnar nerve injury such as compression or entrapment neuropathies.
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The posterior cord
(C5 to T1) gives rise to the radial nerve.
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Used to supplement
a brachial plexus block or as diagnostic and therapeutic block for
radial nerve injury (i.e., humeral fracture).
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Ilioinguinal
and Iliohypogastric
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The ilioinguinal
and iliohypogastric nerves originate from the L1 nerve root. A small
contribution from T12 can also exist. The iliohypogastric nerve
courses between the transverse and external oblique abdominal musculature.
It divides into lateral and anterior cutaneous branches at the level of
the iliac crest. The lateral branch provides sensation to the posterolateral
gluteal area. The anterior branch sends sensory fibers to the skin
of the abdomen around the pubis.
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The ilioinguinal nerve is typically smaller. It lies slightly
lateral to the iliohypogastric nerve, traversing the internal oblique
muscle following the spermatic cord into the inguinal canal. Sensation
is provided to the inner thigh, upper part of the scrotum in men
and mons pubis and lateral labia in women.
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Inguinal hernia
operations and to diagnose and treat postherniorrhapy nerve entrapment.
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Mark 1 in. medial to
the anterior superior iliac spine and draw a line between this area
and the umbilicus. A 25-gauge 1½—in.
needle can be used to inject 8 to 10 mL of local anesthetic solution
fanwise in an up and down direction.
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Bleeding if femoral
artery or vein is punctured.
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Lateral Femoral
Cutaneous
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The lateral femoral
cutaneous nerve is formed from the posterior divisions of L2 and
L3 within the psoas muscle. It passes into the thigh slightly medial
to the anterior superior iliac spine and beneath the inguinal ligament.
It provides sensation to the anterolateral thigh and buttock.
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Diagnosis and treatment
of meralgia paresthetica.
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Approximately 1 in.
medial to the anterior iliac spine and just inferior to the inguinal
ligament. A 25-gauge 1½-in. needle is
inserted perpendicular to the skin advanced slowly until a paresthesia
is obtained. Then 5 mL to 10 mL of local anesthetic solution can
be injected.
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Bleeding if femoral
artery or vein punctured. Pain at injection site.
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The sciatic nerve
contains most of the sensory and sympathetic fibers of the leg.
It is the largest nerve in the body originating from anterior divisions
of L4, L5, S1, S2, and S3. This nerve leaves the pelvis through
the sciatic notch below the piriforms muscle, then courses between
the greater trochanter of the femur and ischial tuberosity. In the
thigh it branches to the hamstring and adductor magnus muscles before
dividing into the common peroneal and tibial nerves behind the head of
the fibula.
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For surgery or manipulation
of the leg below the knee. Diagnostic and therapeutic block for
sciatic nerve injury (i.e., trauma or hip fracture) piriformis syndrome.
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Hematoma in buttocks
or nerve damage.
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The femoral nerve
is formed by the dorsal divisions of the anterior rami of the second
(L2), third (L3), and fourth (L4) lumbar segments. It emerges from
the psoas muscle and is primarily responsible for extension of the
thigh. It passes into the thigh underneath the inguinal ligament
and just lateral to the femoral artery. The femoral nerve sends
branches to the sartorius, quadriceps femoris, and pectinus muscles
along with sensory branches to the skin overlying anteromedial thigh.
It terminates in the lower leg as the saphenous nerve, which supplies
sensation to the skin on the medial aspect of the leg.
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Can be combined with
a sciatic nerve block for surgical manipulation of the leg. Diagnosis
of femoral nerve damage or entrapment.
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Intravascular injection,
or hematoma. Nerve injury.
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Lower Extremity:
Knee
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Common Peroneal
Nerve Block
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The common peroneal
and the tibial nerve are the two major peripheral branches of the
sciatic nerve. This nerve enters the lower leg behind the head of
the fibula, where it then courses laterally around the neck of the
fibula before dividing into the deep peroneal and superficial peroneal nerves.
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Generally used in
combination with tibial and saphenous nerve blocks for analgesia
of the lower leg.
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Injury to nerve
adjacent to neck of fibula.
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After branching off
from the sciatic nerve, this nerve courses through the popliteal
fossa into the lower leg deep between the heads of the gastronemius
muscle which it supplies. This nerve becomes superficial at the
ankle passing between the medial malleolus and Achilles’ tendon before
dividing into the lateral and medial plantar nerves. It supplies
sensation to the skin of the heel and medial sole of the foot.
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Supplement inadequate
sciatic block for lower extremity interventions.
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Lower Extremity:
Ankle
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See previous
section for discussion.
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Deep Peroneal
Nerve Block
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The common peroneal
nerve branches into the deep and superficial peroneal nerves. This
nerve enters the foot medial to the tendon of the hallucis longus
muscle. It supplies fibers to the tarsal and metatarsal joints and
the skin adjacent to first and second toes.
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When combined with
a tibial nerve block, almost complete analgesia and sympathetic
blockade of the foot is possible.
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Superficial
Peroneal and Saphenous Nerve Block
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After branching from
the common peroneal, this nerve travels adjacent to the extensor
digitorum longus muscle before dividing into terminal branches just
above the ankle. It supplies sensation to the dorsum of the foot
and first through fifth toes.
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Usually combined
with other nerve blocks around the ankle for surgical anesthesia.
Therapeutic interventions on foot or toes.
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The sural nerve branches
from the posterior tibial nerve entering the foot between the lateral
malleolus and the Achilles’ tendon. It provides sensation
to posterior lateral aspect of the lower calf, lateral side of the
foot and small toe.
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Operative and therapeutic
interventions on the foot and toes.
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