Sciatic Nerve Injection

Other Names

The course of the sciatic nerve in the lower limb

• Sciatic Nerve Injection
• Sciatic Nerve Hydrodissection

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Background

Key Points

• Needle: 22 gauge, 3.5 inch needle
• Transducer: linear or curvilinear depending on body habitus
• Do not inject into the nerve or surrounding vessels
• Circumferential hydrodissection should be considered

Anatomy of the Sciatic Nerve

• Formed from lumbosacral plexus nerve roots L4-L5, S1-S3
• Motor innervation: biceps Femoris, semimembranosus, semitendinosus, motor component of adductor magnus
• Anatomic course
  • Exits the sciatic foramen, passes below the piriformis, gluteus maximus
  • Lies posterior to quadratus femoris, just lateral to ischial tuberosity
  • Tracks inferiorly and anterior to biceps femoris
  • Bifurcates into the tibial nerve, common fibular nerve in the posterior thigh

Palpation Guidance vs Ultrasound Guidance

• This procedure can not be safely performed with palpation guidance

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Indications

Ultrasound anatomy of sciatic nerve with structures as labeled

Transverse sonogram between the greater trochanter and ischial tuberosity showing the hypoechoic subgluteal space between the hyperechoic perimysium of the gluteus maximus and the quadratus femoris muscle. The sciatic nerve is seen as a hyperechoic nodule in the medial aspect of the subgluteal space

• Sciatica
  • Can be entrapped in the gluteal triangle
• Piriformis Syndrome
• The sciatic nerve is vulnerable following
  • Hamstring Strain
  • Proximal Hamstring Injuries

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Contraindications

• Absolute
  • Anaphylaxis to injectates
  • Overlying cellulitis, skin lesion or systemic infection
• Relative
  • Can be treated with less invasive means
  • Hyperglycemia or poorly controlled diabetes
  • Lack of symptom improvement with previous injection

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Procedure

Needle and probe position with the patient in the lateral decubitus position

Hydrodissection of the sciatic nerve. The needle (thin arrows) is inserted within the fascia layer (arrowheads) between the two muscles

Equipment

• Sterile prep (i.e. chloraprep, chlorhexidine, iodine, etc)
• Gloves
• Needle: typically 22 gauge, 3.5 inch needle
• Syringe: 5-10 mL
• Gauze
• Ethyl Chloride
• Bandage
• Injectate
  • Local anesthetic
  • Corticosteroid
• Sterile probe cover

Ultrasound Findings

• How to identify the sciatic nerve
  • Palpate the greater trochanteric, ischial tuberosity
  • Place the transducer in an axis connecting these two landmarks
  • Identify greater trochanter, ischial tuberosity
  • Gluteus maximus will be the large, superficial muscle group
  • Quadratus femoris lays deep to the sciatic nerve
  • The hyperechoic sciatic nerve bundle should be in short axis between them

Technique: Short Axis, In Plane

• Patient Position
  • Prone
  • Alternatively, the patient can be placed in the lateral decubitus position
• Transducer position
  • Short axis to sciatic nerve
• Needle Approach/ Orientation
  • In Plane
  • Lateral to medial
• Target
  • Sciatic nerve perineurium
• Pearls and Pitfalls
  • Lateral to medial approach helps avoid intravascular injection

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Aftercare

• No significant restrictions
• Can augment with ice, NSAIDS

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Complications

• Skin: Subcutaneous fat atrophy, skin atrophy, skin depigmentation
• Painful local reaction
• Infection
• Hyperglycemia
• Tendon, nerve or blood vessel injury

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See Also

• Procedures Main
• Ultrasound Main
• Back Pain Main
• Hip Pain Main

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