Phenol blocks for spasticity management

1. Chemo-neurolysis – a lost art ?
Mrinal Joshi
Director, Rehabilitation Research Center
Prof & Unit Head, Dept. of Phys. Med. & Rehabilitation
Nodal Officer, Disability Board
SMS Medical College & Associated Hospital
Editor, IJPMR & PMR Buzz
Jaipur

3. Phenol & Medicine – Milestones
• 1860 – Sir Joseph Lister used it as antiseptic agent during surgery
• 1903 – Schlosser reports injection of alcohol in nerves for neuralgia
• 1912 – May publishes its functional and histologic effects
• 1919 – Lijestrand and Magnus show reduction of triceps rigidity in
decerebrate cat after i.m. procaine injection
• 1959 – Nathan and Kelly describe technique for intrathecal phenol injection
for spasticity
• 1964 – Tardieu and Hariga perform motor point inections using dilute
alcohol and electric stimulation
• 1964 – Khalili & associates publish injection techniques for peripheral
nerve blocks using 2% to 7% phenol solution
• 1965 – Halpern & Meelhuysen publish motor point block technique using
low dose of phenol solution

4. Focal Spasticity Toolbox
• Chemo-denervation
• Has become primary treatment of choice
• Explosion of article
• But high cost (approx. $200 each vial)
• Recurrent cost (each treatment cost more than $500)
• Neurolysis
• Pre-botulinum era
• Only option for focal spasticity
• Low cost ($20 each treatment cost)
• Surgical intervention

5. Nerve blocks
• Process of applying chemical agents to various nerve structures to
intentionally interfere with nerve conduction
• Are performed for pain management
• For spasticity management
• Intramuscular motor point block
• Selective motor branch block of nerves
• Motor nerve block
• Diagnostic nerve block – for evaluation
• Therapeutic nerve block – neurolysis

6. Fading art
• Despite long history and safety profile
• Frequency of use has declined
• Many centers – completely abandoned
• Many do not feel confident in performing
• Most registrars have never performed during residency
• Though effective
• No marketing or sponsored studies
• Remains a cost-effective option

7. Phenol
• Carbolic acid
• Benzyl alcohol and derivative of benzene

8. Spasticity Management
• Closed peri-neural injection
• Closed motor branch block
• Open motor branch block
• Motor point block
• Primary use in nerves with minimal sensory input

9. Aqueous or Glycerol
• Glycerol - diminishes the necrotizing effect
• Aqueous solution induces marked endoneural damage
• Aqueous solution - penetrates the perineurium better
• 3-5% solution for percutaneous blocks
• 3% glycerine solution favoured for open blocks

10. Effect
• Reduces amplitude of M-Response
• Relative preservation of voluntary strength
• Destroys axons
• Type I alpha affected preferentially
• Others indicate, blocks all fibers
• Long term histology shows persistent fibrosis

11. Duration of Effect
• Site of block
• Concentration and volume
• Procedural dexterity
• Date of manufacturing
• Repeated injections
• Effect : Average six months

12. Side Effect
• Local Pain & Swelling
• Dysesthesia : 2 to 32%
• Peripheral Edema
• Tremors & Convulsions
• CNS Depression
• Deep Venous Thrombosis
• Cardiovascular Collapse
• Prolonged Sensory Loss – Rare

13. Side Effect
• Skin slough
• Extreme motor weakness
• Accidental intravascular injection

14. Dose
• 0.25-0.5 ml of 5-6% of solution
• Lethal dose of Phenol 8.5 gm
• Zafonte et al recommend 1gm/session
• Maximum - 20ml of 5% aqueous solution

15. Problem Nerve Block Motor Point Block
Shoulder Internal Rotation Pectoral Nerve Pectoralis
Subscapularis
Arm adduction Thoraco-dorsal nerve Latissimus Dorsi
Elbow Flexion Musculo-cutaneous Biceps, Brachioradialis
Wrist Flexion Flexor Carpi Ulnaris, Flexor
Carpi Radialis
Finger flexion Flexor Digitorium Superficialis
Thumb In Palm Recurrent Motor Branch
of Median
Opponense Pollicis, Flexor
Pollicis Longus, Flexor Pollicis
Brevis

16. Problem Nerve Block Motor Point Block
Knee Flexion – Hamstring
spasm
Flexor spasms
Sciatic Proximal Nerve
Sciatic Distal Nerve
Hamstrings
Scissoring – Hip adduction
spasticity
Obturator Nerve Adductor longus
Equinus – Planter flexor
spasticity
Post-tibial Nerve Gastrocnemius
Hip flexion Ilio-psoas
Stiff knee – knee extensor
spasticity
Rectus femoris

23. Sciatic Nerve
SCIATIC NERVE
PERONEAL PART
TIBIAL PART
BICEPS FEMORIS
SEMITENDINOSUS
*fig from atlas of anatomy by F Netter

24. Sciatic Nerve Block
Posterior Approach
1.Post. Super. Iliac Spine
2.Great. Trochanter

25. Sciatic Nerve Block - Distal
From ischial tuberosity
• 20% of femur length
• 33% of femur length
• Towards lateral femoral
condyle.

26. Obturator Nerve
OBTURATOR NERVE
Anterior Branch
Posterior Branch
*fig from atlas of anatomy by F Netter

27. Obturator Nerve Block
• Mark 2 cm medial to femoral
artery, below inguinal ligament
• Palpate adductor longus tendon
• 2 cm below and lateral from
pubic tubercle