Spasticity: Why Tight Muscles Are Not a Cramp, When Not to Treat Them, and the Baclofen Rules
Spasticity is a specific thing, and it gets confused with everything else that makes muscles feel tight. It is not a cramp, not a strain and not the stiffness of Parkinson disease. It is a velocity-dependent increase in muscle tone — the faster a limb is moved, the more it resists — and it comes from damage to the pathways running from the brain down the spinal cord.
That single definition explains the examination finding, the drug choice and the one clinical judgement that matters most here: whether to treat it at all.
🔄 Four kinds of tight muscle
| What it is | How it behaves | |
|---|---|---|
| Spasticity | Upper motor neuron damage | Worse the faster you move the limb. A catch then a release, exaggerated tendon reflexes, often a clonus at the ankle. Usually with weakness in the same limb |
| Muscle spasm | A protective reflex after injury | Localised, follows a specific strain, settles over days to weeks. Covered in our guide to acute muscle pain and spasm |
| Cramp | Sudden involuntary contraction | Calf or foot, seconds to minutes, relieved by stretching. Nothing to do with the spinal cord |
| Rigidity | Parkinson disease and related conditions | Not velocity-dependent — the resistance is the same slow or fast, in both directions. Normal reflexes |
Clinicians grade it on the modified Ashworth scale from 0 to 4, where 0 is normal tone and 4 is a limb rigid in flexion or extension. Knowing your own grade is useful, because it is the number that treatment decisions are measured against.
🧠 Where it comes from
- 🩸 Stroke — the commonest cause, developing over weeks to months afterwards, typically flexion at the elbow and wrist and extension at the ankle
- 🦴 Spinal cord injury — often with spasms triggered by touch or movement
- ⚡ Multiple sclerosis — one of its most disabling features. The disease itself is covered in our guide to multiple sclerosis
- 🧒 Cerebral palsy — present from early childhood, with growth and contracture adding complications over time
- 🛡️ Traumatic brain injury, and brain or spinal tumours
- 🧬 Hereditary spastic paraplegia and other inherited conditions, often with slow progression over years
⚖️ The judgement that comes before any drug
💡 Spasticity is sometimes useful, and this is the thing most often got wrong.
Increased extensor tone in a weak leg can be what allows someone to stand, transfer from a chair, or walk with a stick. Reduce it and the leg becomes a soft weak limb that will not hold weight. The person is left more comfortable and less able.
So the first question is never how do we lower the tone. It is what is the tone actually costing you — pain, interrupted sleep, difficulty with dressing or washing, a hand that cannot be opened to clean, difficulty with catheterisation, pressure areas, or a contracture forming. Treatment is aimed at those specific problems, and the effect on function is checked afterwards.
A clearly stated goal before starting — I want to be able to straighten my fingers to clean the palm, or I want to sleep without being woken by spasms — is what makes it possible to tell whether treatment worked.
🔍 Sudden worsening: look for the cause, do not raise the dose
Spasticity is sensitive to anything painful or irritating below the level of the injury, even when the sensation itself is not felt. A noticeable increase over days, or new spasms, is usually a message rather than disease progression.
| Look for | Why it matters |
|---|---|
| Urinary infection | The commonest trigger by a wide margin. Often without fever or burning in spinal cord injury |
| Constipation or a loaded bowel | Second commonest, and easily fixed |
| Pressure sore | Including early redness over the sacrum or heels, which must be looked for rather than waited for |
| Ingrown toenail, or anything tight | Shoes, a splint rubbing, a catheter strap, a leg bag. Genuinely this trivial, and genuinely this effective when removed |
| A fracture or injury not noticed because of reduced sensation | Worth imaging if nothing else is found |
| Deep vein thrombosis | A swollen warm calf needs assessing urgently in its own right |
| A new medicine | Several drugs raise tone or lower the seizure and spasm threshold |
Working through that list first prevents a great deal of unnecessary dose escalation, and it finds problems that matter more than the spasticity.
🧘 Physical management, which is not the soft option
No drug maintains range of movement. Drugs reduce tone; stretching and positioning are what stop a tight muscle becoming a fixed contracture, and once a contracture has formed no tablet reverses it.
- 📏 Daily sustained stretch — held for minutes rather than seconds, through the full available range, every day. This is the core of it
- 🪑 Positioning — how someone sits and lies for the other 23 hours matters more than the exercise session. Seating assessment is a specialist job and worth asking for
- 🦿 Splints and serial casting for a limb drifting towards contracture
- 🚶 Standing frames and tilt tables, which load the legs and reduce tone for hours afterwards
- 🏊 Hydrotherapy, where warm water reduces tone enough to allow movement that is impossible on land
- 🌡️ Cold reduces tone briefly and can be used before a stretch; heat helps pain but not tone
The referral to ask for by name is a physiotherapist with a neurological rehabilitation interest, and an occupational therapist for the hand and for daily tasks. General musculoskeletal physiotherapy is a different skill set.
💊 The oral drugs
All of them trade tone against sedation and weakness, which is the limiting factor for every one. Start low, go slowly, and judge by the goal rather than by the Ashworth number.
| Drug | Dose | What limits it |
|---|---|---|
| Baclof (Baclofen) | 5 mg three times daily to start, increasing every three days. Usual effective range 30 to 80 mg daily in divided doses | Drowsiness, weakness, dizziness. Excreted by the kidneys, so the dose is reduced in renal impairment. Never stopped abruptly — see below |
| Zanaflex (Tizanidine) | 2 mg at night to start, increasing by 2 mg every three to four days, up to 24 to 36 mg daily in three or four doses | Sedation, dry mouth and low blood pressure. Needs liver enzyme checks at baseline and at 1, 3 and 6 months. Must not be combined with ciprofloxacin or fluvoxamine, which block its breakdown and can cause a severe drop in blood pressure |
| Dantrolene | 25 mg daily, increased slowly | Acts on the muscle rather than the brain, so less sedating — at the cost of a real risk of liver injury, which makes regular liver monitoring compulsory |
| Neurontin (Gabapentin) | Titrated upwards over weeks | Some benefit in spinal cord injury spasticity, and useful where neuropathic pain coexists, which it often does |
| Benzodiazepines | Low dose, usually at night | Effective and sedating, with tolerance and dependence. Reserved for night-time spasms rather than daytime use |
Often a smaller dose of two drugs is better tolerated than a large dose of one — baclofen plus low-dose tizanidine at night being a common combination. The range sits in the muscle relaxers category.
⛔ Baclofen is never stopped abruptly, and this is the most important safety point on the page.
Sudden withdrawal after regular use causes rebound spasticity far worse than the original, agitation, hallucinations, confusion, seizures and high temperature. It is a recognised and avoidable emergency.
The practical situations in which it happens are ordinary ones: running out of tablets, a prescription not renewed in time, a hospital admission where the drug is omitted from the chart, or being unable to swallow. Treat baclofen as a time-critical medicine, keep a buffer supply, and carry a written list into any hospital.
Reducing it deliberately is done over weeks, in small steps.
💉 When the problem is in a few muscles rather than everywhere
Oral drugs act on the whole body, which is wasteful and sedating when the problem is one arm. Botulinum toxin injected into the specific overactive muscles reduces tone locally without affecting anything else, and is the standard approach for focal spasticity — a clenched hand, an inverted foot, a flexed elbow.
- ⏳ Effect begins in a few days, peaks at two to four weeks and lasts around three to four months, then repeats
- 📏 It only buys a window. Injection combined with intensive stretching, splinting or casting during those weeks is what produces lasting gain in range. Injection alone wastes most of the benefit
- 🎯 Goal-led — a specific task it is meant to make possible, assessed afterwards
- ⚠️ Temporary excess weakness in the injected muscle is the main drawback, and swallowing or breathing problems are a rare but real reason to report any new difficulty promptly
🔧 Severe generalised spasticity: the pump
Where tone is severe throughout the body and oral drugs cause unacceptable sedation before they work, intrathecal baclofen delivers the drug directly into the fluid around the spinal cord through an implanted pump. The dose is in micrograms rather than milligrams — roughly a thousandth of the oral amount — which is why it works without the drowsiness.
It is effective and it is a serious commitment: surgery, refills every few months, and a device that can fail.
🚨 Intrathecal baclofen withdrawal is a life-threatening emergency. If the pump, catheter or battery fails, or a refill is missed, the drug stops abruptly at a dose the body is heavily dependent on.
Signs: spasticity returning worse than ever, high fever, racing heart, agitation and confusion, low blood pressure, progressing to muscle breakdown and multi-organ failure. It can be fatal and it is frequently mistaken for sepsis.
Anyone with a pump should carry a card stating so, and anyone presenting with that picture needs the pump considered immediately. Do not wait for the next clinic appointment if the pump alarms or if spasticity suddenly deteriorates.
Other options where appropriate: selective dorsal rhizotomy, mainly in cerebral palsy in childhood, and orthopaedic surgery for established contractures — tendon lengthening or release — which addresses the fixed shortening that drugs cannot.
📋 What good care looks like
- 🎯 A written goal, specific enough to test
- 🔍 Triggers excluded — infection, bowels, skin, anything tight
- 🧘 A stretching and positioning programme that is actually being done, with specialist input
- 💊 Oral medication only if the problem is generalised, started low and reviewed against the goal
- 💉 Botulinum toxin if the problem is focal, with therapy in the weeks after it
- 🔧 Pump or surgery where severity justifies it, before contractures become fixed
- 🔄 Review — including stopping drugs that are not achieving the goal, rather than adding another
📞 When to seek help
Emergency:
- A baclofen pump alarming, or sudden severe worsening of spasticity with fever, racing heart or confusion — possible intrathecal withdrawal
- Missed oral baclofen with agitation, hallucinations or a seizure
- New swallowing or breathing difficulty after botulinum toxin
- A swollen, warm, painful calf
- A pressure sore with surrounding redness, fever or a bad smell
Promptly:
- Spasticity worsening over days — ask for urine testing and a bowel and skin check before any dose increase
- A joint losing range, or a limb becoming harder to position — a contracture forming is a reason to act now rather than later
- Pain or spasms waking you at night
- Difficulty with washing, dressing, catheterising or transferring because of tone
- Feeling weaker or sleepier since the dose went up — the treatment may be costing more than it gives
- Running low on baclofen, at any point
- Never having seen a neurological physiotherapist — ask to be referred
- Starting ciprofloxacin while taking tizanidine — this combination should not be used
- No liver tests since starting tizanidine or dantrolene
❓ Frequently asked questions
What is the difference between spasticity and a muscle spasm?
Spasticity is a velocity-dependent increase in tone from damage to the pathways between brain and spinal cord — the faster the limb is moved, the more it resists, with exaggerated reflexes. A spasm is a protective reflex after a local injury and settles in days to weeks.
Should spasticity always be treated?
No. Increased extensor tone in a weak leg can be what allows standing and transferring, and reducing it can leave someone more comfortable but less able. Treatment is aimed at specific problems such as pain, broken sleep, hygiene or a forming contracture.
My spasticity suddenly got worse. Why?
Usually something painful or irritating below the level of injury, even if not felt. A urinary infection is the commonest, then constipation, a pressure sore, an ingrown toenail or anything tight. Look for those before increasing any dose.
What is the baclofen dose for spasticity?
5 mg three times daily to start, increasing every three days, with a usual effective range of 30 to 80 mg daily in divided doses. The dose is reduced in kidney impairment because baclofen is cleared by the kidneys.
What happens if I stop baclofen suddenly?
Rebound spasticity worse than the original, plus agitation, hallucinations, confusion, seizures and high temperature. It is an avoidable emergency, so keep a buffer supply, treat it as time-critical in hospital, and reduce only gradually over weeks.
Why does tizanidine need liver tests?
Because it can raise liver enzymes, so they are checked at baseline and at one, three and six months. It also must not be combined with ciprofloxacin or fluvoxamine, which block its breakdown and can cause a severe fall in blood pressure.
When is botulinum toxin used instead of tablets?
When the problem is focal — one clenched hand, an inverted foot, a flexed elbow — rather than generalised. It avoids whole-body sedation, lasts three to four months, and only produces lasting gain if combined with stretching or splinting during that window.
Do stretches really matter if I am taking medication?
Yes, and they do something no drug does. Medication lowers tone; sustained daily stretching and good positioning are what prevent a tight muscle becoming a fixed contracture, and once a contracture forms no tablet reverses it.
What is an intrathecal baclofen pump?
An implanted pump delivering baclofen directly around the spinal cord in micrograms rather than milligrams, which controls severe generalised spasticity without the drowsiness of oral doses. It needs surgery and regular refills.
What are the warning signs of pump failure?
Spasticity returning worse than ever, high fever, racing heart, agitation, confusion and low blood pressure. It is life-threatening, often mistaken for sepsis, and needs the pump considered immediately rather than at the next appointment.
📑 Sources and editorial
- National and specialist society guidance on the management of spasticity in adults following stroke, spinal cord injury and multiple sclerosis
- Definitions of spasticity within the upper motor neuron syndrome, and the modified Ashworth scale
- Rehabilitation guidance on noxious stimuli precipitating increased tone, including urinary infection, constipation, pressure ulceration and ill-fitting orthoses
- Evidence on sustained stretch, positioning, serial casting, standing and hydrotherapy in the prevention of contracture
- Prescribing information for baclofen, tizanidine, dantrolene, gabapentin and benzodiazepines in spasticity, including renal dose adjustment for baclofen and hepatic monitoring for tizanidine and dantrolene
- Safety communications on the tizanidine interaction with ciprofloxacin and fluvoxamine
- Case series and guidance on oral baclofen withdrawal syndrome and on intrathecal baclofen withdrawal, including presentation and emergency management
- Randomised evidence for botulinum toxin in focal spasticity, including the requirement for adjunctive therapy during the period of effect
- Outcome data for intrathecal baclofen therapy and for selective dorsal rhizotomy
- Related reading: multiple sclerosis, acute muscle pain and spasm
- Related products: Baclof (Baclofen), Zanaflex (Tizanidine), Neurontin (Gabapentin), muscle relaxers category
- RXshop Editorial Team — reviewed by James Carter, MD — Neurologist & Sleep Medicine Specialist
Medical Disclaimer: The information in this article is for educational and informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek guidance from a qualified healthcare provider with any questions you may have regarding a medical condition, and before starting, stopping or changing any medication.