Nerve block for spasticity
An injection of phenol or alcohol onto a nerve or muscle motor point to calm overactive, stiff muscles, used for selected spasticity alongside therapy when other measures are not enough.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- A nerve block uses phenol or alcohol to calm overactive muscles, often larger ones, when stiffness is causing problems.
- It is targeted and used alongside therapy; it does not cure the underlying brain or spinal condition.
- The effect commonly lasts several months — sometimes longer than botulinum toxin — but is generally temporary and can be repeated.
- It is a specialist procedure needing accurate nerve location and an experienced clinician; sensory side effects are a particular consideration.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your specialist will give you advice for your situation.
Calms overactive, stiff muscles, including larger ones that may be harder to treat with toxin alone.
A fixed contracture (a permanently shortened muscle or joint) will not respond and needs a different approach.
Soreness, and sometimes bruising or swelling, at the injection sites. Most people go home the same day; arrange transport if you had sedation.
A clear, goal-based plan with therapy and splinting arranged around the block.
Soreness, and sometimes bruising or swelling, at the injection sites. Most people go home the same day; arrange...
The muscle-relaxing effect develops. Any altered sensation usually becomes apparent in this period.
The effect settles and therapy, stretching and splinting make the most of the reduced stiffness.
The benefit is at its most useful, then gradually fades.
What is a nerve block for spasticity?
A nerve block for spasticity uses an injection of a chemical — usually phenol or alcohol — placed onto a nerve, or onto the 'motor points' where nerves enter a muscle, to reduce the signals that make that muscle overactive and stiff. This is called chemical neurolysis. It is used for selected spasticity, often in larger muscles or muscle groups, when stiffness is causing problems.
Like botulinum toxin, it is a targeted treatment aimed at specific muscles rather than the whole body, and it is used alongside therapy. It is sometimes chosen for bigger muscles, when many large muscles need treating, or when botulinum toxin alone is not enough or its dose would be exceeded.
The effect builds over days and commonly lasts several months, sometimes longer than botulinum toxin, but it is still generally considered temporary and can be repeated. It is not a cure for the underlying condition.
It is a more specialised procedure than a botulinum toxin injection, needing accurate nerve location (usually with electrical stimulation or ultrasound) and a clinician experienced in the technique. As with all spasticity treatment, it works best as part of a wider plan with stretching, splinting, positioning and therapy.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
Nerve block versus botulinum toxin
| Nerve block (phenol/alcohol) | Botulinum toxin | |
|---|---|---|
| Often suits | Larger muscles or many muscles | Smaller, specific muscles |
| Typical duration | Several months, sometimes longer | About 3–4 months |
| Particular risk | Altered sensation on mixed nerves | Temporary local weakness, rare spread |
| Technique | More specialist nerve location | Targeted muscle injection |
They are not rivals — they are often used together for different muscles. Your specialist chooses based on which muscles are involved and your goals.
Preparing for your procedure
- Agree clear goals with your specialist — which muscles, and what the block is meant to improve.
- Bring a list of medicines and doses, and mention any blood-thinning medicines or bleeding problems.
- Tell the team about pregnancy or breastfeeding, infection near the injection site, or previous reactions to injections.
- Discuss the sensation risk if a nerve that also carries feeling is to be treated.
- Arrange the therapy, splinting or follow-up that should go alongside the block.
- Ask whether local anaesthetic, sedation or, occasionally, general anaesthetic will be used, and prepare accordingly (for example transport if sedated).
- Wear clothing that allows easy access to the area being treated.
What happens
After examining you and confirming the goals, the specialist locates the target nerve or motor points, usually using a fine needle that delivers a small electrical stimulus (and often ultrasound) to confirm the right spot — you may see the muscle twitch. Local anaesthetic is generally used; sedation or a general anaesthetic is occasionally needed, for example in children or for extensive treatment.
Small amounts of phenol or alcohol are then injected at the identified points. The procedure usually takes around 20–45 minutes, depending on how many nerves or muscles are treated.
Most people go home the same day. Some soreness is normal. Therapy, stretching or splinting is usually planned in the days afterwards to make the most of the reduced stiffness.
Is this procedure right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- A fixed contracture (a permanently shortened muscle or joint) will not respond and needs a different approach.
- Where altered sensation would be unacceptable, blocks on mixed motor-and-sensory nerves may be avoided in favour of motor points or botulinum toxin.
- Infection or skin breakdown over the injection site.
- A bleeding disorder or blood-thinning medicine that cannot be safely managed.
- If there are no clear functional, care or comfort goals, the procedure may not be justified.
Delay or rearrange if…
- There is active infection at or near the injection site.
- You are pregnant or breastfeeding, where treatment is generally avoided unless specifically advised.
- Aggravating factors such as a urine infection or constipation are temporarily worsening the spasticity.
- A bleeding problem or anticoagulant needs review and adjustment first.
- Goals have not been agreed, so it is unclear which nerves or muscles to target.
Alternatives to discuss
- Botulinum toxin injections, especially for smaller muscles.
- Oral spasticity medicines for more widespread stiffness.
- Physical management alone — stretching, positioning, splinting and therapy.
- Specialist intrathecal baclofen pump assessment for severe, widespread spasticity.
- No block if the stiffness is mild, useful, or better treated another way.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Comfort, sedation or contrast choices
If local anaesthetic, sedation, contrast or pain relief is used, ask what is planned, why, and what it means afterwards.
Benefits
- Calms overactive, stiff muscles, including larger ones that may be harder to treat with toxin alone.
- Can make positioning, washing, dressing and care easier.
- May reduce pain and spasms from tight muscles.
- Can improve a limb's position and, for some, function or standing and walking.
- Effect often lasts several months, sometimes longer than botulinum toxin.
- Allows large muscles to be treated while saving toxin for smaller ones.
Risks & complications
- Soreness, bruising or swelling around the injection site.
- More weakness than wanted in the treated muscles for a time.
- Altered sensation, tingling or numbness, especially if a nerve that also carries feeling is treated.
- The effect wearing off over months, needing repeat treatment.
- Painful or unpleasant sensations (dysaesthesia) along the nerve, which can persist for a time.
- Local infection at an injection site.
- Bruising or a small collection of blood, particularly with blood-thinning medicines.
- Not every goal being fully met, needing a change of plan.
- Longer-lasting sensory disturbance or chronic nerve pain.
- An unwanted effect on nearby structures from spread of the chemical.
- An allergic or systemic reaction.
The most distinctive risk of a phenol or alcohol block is altered or unpleasant sensation when a nerve that also carries feeling is treated — which is why motor nerves or motor points are usually chosen, and accurate location matters. Tell your specialist about bleeding risks and sensation problems, and ask how they will reduce the sensory risk and what to do if pain or numbness develops. An experienced clinician and careful targeting are key.
Published figures to discuss
Exact complication rates for chemical neurolysis vary by agent (phenol or alcohol), the nerves treated, technique and the underlying condition, and we will not invent precise figures. The most relevant points for patients are that altered or unpleasant sensation is a recognised, distinctive risk when sensory fibres are affected, that local weakness and soreness are expected, and that the effect, while often lasting several months, generally wears off and may be repeated. Targeting motor nerves or motor points and accurate location reduce the sensory risk.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Temporary weakness or numbness | Expected/technique-dependent | Diagnostic blocks deliberately reduce nerve activity and may temporarily affect function. | Phenol nerve block — StatPearls (NCBI Bookshelf)ncbi.nlm.nih.govSource-linked context |
| Pain, bleeding, infection or nerve irritation | Uncommon to rare | Risk depends on site, medicines such as anticoagulants, sterile technique and guidance method. | Phenol nerve block — StatPearls (NCBI Bookshelf)ncbi.nlm.nih.govSource-linked context |
| Functional worsening despite reduced tone | Recognised | Some people use spasticity to stand or transfer, so goals must be tested before permanent treatment. | Guide sourcesClinical context |
| Short-lived benefit | Expected for diagnostic local anaesthetic blocks | Temporary response may guide longer-acting phenol, botulinum toxin, orthotic or surgical options. | Guide sourcesClinical context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
There is little physical recovery from the injection itself, beyond some soreness. 'Afterwards' is about the effect building over days, the therapy planned around it, and the effect gradually wearing off over months.
- Soreness or bruising at the injection sites for a few days.
- The treated muscles gradually loosening over the first days to weeks.
- Some tingling or altered sensation, which often settles.
- The effect lasting several months before fading.
- Best results when stretches, splinting and therapy are kept up.
Aftercare
- Keep up the stretches, splinting, positioning and therapy planned around the block — this is what makes it work.
- Watch the injection sites for signs of infection (spreading redness, heat, swelling).
- Report new or persistent pain, burning or numbness along the nerve to your specialist.
- Note what improves and what does not, to guide future treatment.
- Continue any oral spasticity medicines unless told otherwise.
- If you had sedation, rest and do not drive that day as advised.
- Attend your review so the effect and goals can be assessed.
- Clear, agreed goals and which muscles are being treated
- Therapy, stretching or splinting arranged to follow
- An up-to-date medicines list, including any blood thinners
- Understanding of the sensation risk and what to report
- Transport arranged if sedation is planned
- A note of how the limb is before treatment, to compare after
- A review appointment booked
Scars and how they heal
There are no surgical scars. You may have small needle marks and some bruising or swelling at the injection sites, which settle over days. No stitches or wound care are needed.
⚠ Get urgent help if…
- New, severe or persistent burning pain, numbness or unpleasant sensations along the nerve.
- Spreading redness, heat, swelling or discharge at an injection site (possible infection).
- A rash, facial swelling or breathing difficulty soon after the injection (possible allergy).
- Severe or unexpected weakness that affects safety, such as with standing or transfers.
- A large, painful or expanding bruise, especially if you take blood thinners.
- Any new symptom that worries you in the days after treatment.
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your specialist gives you.
Results & realistic expectations
A good result is meeting the agreed goal — for example easier positioning or care, less pain or spasm, or a better-positioned limb — for the months the block is active, with therapy used to make the most of it. The effect builds over days and can last several months.
The block cannot cure the underlying condition and will not help a fixed contracture (a permanently shortened muscle or joint). Its effect is generally temporary, so repeat treatment may be needed, and results vary depending on which nerves and muscles are treated and how therapy is combined with it.
The benefit of a nerve block commonly lasts several months and sometimes longer, because nerve fibres recover gradually. It can be repeated when it continues to help. Over time, your specialist reviews whether to repeat the block, switch to or add botulinum toxin, or consider other options, depending on your goals and response.
Related tests, treatments or support
Nerve blocks are frequently combined with botulinum toxin for different muscles (for example a block for large muscles and toxin for smaller ones), with oral spasticity medicines, and always with physiotherapy, stretching and splinting. The overall plan is coordinated by a rehabilitation team and tailored to your goals.
Follow-up & long-term care
You will usually be reviewed a few weeks after the block to assess the effect against your goals, with further review as it wears off to decide about repeating. Therapy continues alongside. Your specialist adjusts the approach — block, toxin, medicines or a combination — based on how you respond.
- Repeat blocks when the effect wears off and they continue to help.
- Ongoing stretching, splinting and therapy between treatments.
- Review of goals and response at each cycle.
- Combining or switching with botulinum toxin or oral medicines as needed.
- Monitoring for and managing any persistent sensory symptoms.
Repeat, follow-on and what comes next
- Blocks are repeated when their effect wears off and they continue to help.
- The approach is often adjusted between sessions, or combined with botulinum toxin and medicines.
- If a block does not meet goals or causes troublesome sensory symptoms, the plan is reviewed rather than simply repeated.
- Some people are better served by switching between block and toxin over time.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- A clear, goal-based plan with therapy and splinting arranged around the block.
- Review a few weeks later to assess the effect against goals.
- Clear written warning signs, including about new pain or numbness.
- A plan for repeating, combining or switching treatment based on response.
- A named contact and joined-up communication with your team and GP.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- The number of nerves or muscles treated and the number of sessions.
- Whether nerve location uses electrical stimulation and ultrasound guidance.
- Whether local anaesthetic, sedation or general anaesthetic is used (a general anaesthetic adds anaesthetist and facility costs).
- The specialist's fee and the clinic or facility fee.
- Therapy, splinting or equipment provided alongside, usually charged separately.
- How often blocks need repeating and the frequency of review.
- The fee for each block session and what it includes.
- Whether nerve-location guidance is included.
- Whether sedation or general anaesthetic, with its own fees, is needed.
- What therapy or splinting is included or charged separately.
- How often repeat treatment is expected and its cost.
- Whether a written plan and a letter to your GP are included.
- What happens, and any cost, if the block does not achieve the goal or causes a side effect needing follow-up.
On the NHS? Nerve blocks for spasticity are available on the NHS through specialist rehabilitation services when clinically indicated; private treatment is generally used for faster access or more choice rather than because it is unavailable on the NHS.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Not explaining the distinctive risk of altered or unpleasant sensation.
- Promising a permanent result when the effect is generally temporary and repeated.
- Injecting without clear, agreed goals or without the therapy that makes it work.
- Not checking bleeding risk, infection, pregnancy or suitability beforehand.
- Not setting out who is experienced in the technique and how the nerve is located.
Marketing red flags
- Presenting a nerve block as a one-off 'cure' for spasticity.
- Offering blocks without therapy, goals or specialist assessment.
- Downplaying the sensory risk or the need to repeat treatment.
- No discussion of suitability, side effects or warning signs.
Choosing a specialist safely
- Check the specialist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good specialist will welcome every one of these.
- Which nerves or muscles will you treat, and what specific goal are we aiming for?
- How will you locate the nerve, and how will you reduce the risk of altered sensation?
- Would botulinum toxin, a nerve block, or both be best for me?
- How long should the effect last, and when might we repeat it?
- What side effects should I expect, and what should I report urgently?
- What therapy or splinting should I do afterwards?
- What is the plan if this does not achieve the goal?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the specialist who carries out my procedure, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this procedure not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
How is a nerve block different from botulinum toxin?
How long does it last?
Will it cure my spasticity?
Does it hurt, and will I be awake?
Could it affect my feeling in the limb?
Is it available on the NHS?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: RCP/BSRM — Spasticity in adults: management using botulinum toxin (national guidelines, 2018) Phenol nerve block — StatPearls (NCBI Bookshelf) Phenol block for upper limb spasticity — ACNR Phenol and alcohol blocks for the treatment of spasticity (PM&R Clinics) Stroke Association — Spasticity and contractures NICE NG236 — Stroke rehabilitation in adults (national guideline, 2023; includes spasticity) NICE CG145 — Spasticity in under 19s: management (national guideline, 2012, updated 2016)
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
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