What is Interscalene Block?
Interscalene and Brachial Plexus Blocks : Interscalene block is a procedure of inhibiting sensations around the shoulder, elbow and upper arms region. This is a pre and post-surgery procedure done on the arms to reduce pains during surgery. Consider interscalent block as an anesthetic technique done in the upper limb region.
An interscalene block can be done alone or in combination with general anesthetic for pain control. However, interscalene block is not recommended for hand surgery as the inferior trunk may be spared during anesthetization.
An interscalene block anesthetizes most of the Brachial Plexus. Under ultrasound visualization, the brachial plexus is seen as 2 or 3 circles that are equivalent to the superior, middle and inferior trunks. The inferior trunk may not be seen as it should when the muscles around the region get thicker. The brachial plexus can also be identified by palpation.
The interscalene groove -a space between scalene muscles is palpable, the space is behind the lateral head of sternocleidomastoid muscle and adjacent to the Chaissaignac’s tubercle.
When do people undergo Interscalene Block procedure?
To undergo an Interscalent block, one must have had a fracture or tendon tear in the upper arm, elbow and shoulder region and will need a surgical operation.
Common injuries include:
- Rotator Cliff Injury: This injury affects the muscles that link your humerus to your shoulder blade and an injury in the pain causes shoulder pain and inability to move the shoulders.
- Sinew Repair: The sinew is a tendon that connects the muscles and bones together. This tendon can tear or get damaged, causing a painful sensation and inability to move the joint. It is a common sports injury prevalent in football, rugby and wrestling.
- Humerus fracture or dislocation: This is when the bone in the upper arm gets broken or dislocated.
Why is Interscalene Block preferred to other anesthetic procedures?
- Faster healing time
- Lesser negative effect
- Reduced pain
What nerves are affected during Interscalene Block?
An interscalene block anesthetizes most of the Brachial Plexus. The Brachial Plexus is a group of nerves interconnection that supplies impulses of sensations to the upper limbs. The Brachial Plexus ends at the cervical spine after passing through the anterior and scalene muscles and around the artillery artery. It is formed by the ventral rami of the fifth to eighth cervical nerves and a larger part of the ventral ramus of the thoracic nerve.
The nerves in the Brachial Plexus include Subclavius, Dorsal Scapular, Long Thoracic, Suprascapular, Subscapular, Thoracodorsal, Auxilliary, Pectoralis, Radial, Musculocutaneous, Ulinar, and Median nerves.
Complications and Risks associated with Interscalent Block?
- Hemi-paralysis of the diaphragm
- Patient can also complain of shortness of breath, this happens when the volume of the anesthetic reaches the phrenic nerve.
- Anesthetic toxicity: Commonly used anesthetic have maximum dosage, exceeding this dosage can cause anesthetic toxicity.
- Permanent nerve injury
- Brain damage
- Slow heartbeats
- Low blood pressure
- Carotid artery puncture
People that cannot take the procedure?
- People with proven allergies to certain medications and specific anesthetics. Ester local anesthetics have Para-Aminobenzoic Acid (PABA) which is a known allergen.
- Pregnant women are not advised to undergo this procedure due to its risk in child formation.
- People using Blood Thinners such as Apixaban, Dabigatran and Edoxaban. Blood thinners are medications prescribed to reduce the risk of heart attacks or strokes when there is an unusual collection of blood outside the blood vessels.
- Patient’s refusal to undergo the procedure; children under 18 need parental consent to have an interscalene block.
Is it normal to have pain after Nerve Block?
Yes, it is expected to have soreness in the region, it is expected to heal within few days. Patient also loses sensitivity or sensation in the region for hours but within a day after the surgical procedure.
Equipment and things needed for an Interscalene Block?
- Sterile gloves
- Injection pressure monitor
- A 3-mL Syringes
- A 20-30mL syringe
- Local anesthetics
- Two-inch 22-gauge insulated simulating needle
- Nerve simulator
- Marking pen and ruler
- Skin prep i.e. alcohol, betadine
Who performs the procedure?
An interscalene block requires two people. An anesthesiologist or an anesthetic specialist and an anesthetic nurse are expected to carry out the procedure. They are also expected to explain the risks and complications to patients and have their consent before proceeding.