What causes spaticity?

A stroke occurs when the blood supply to a part of the brain is interrupted or severely reduced. If blood flow is cut off for longer than a few seconds, the brain does not receive enough blood and oxygen to fulfil its functions. Consequently, nerve cells die, causing lasting damage.²

There are two major types of stroke²:

• Ischaemic: an ischaemic stroke occurs when a brain artery is blocked by a blood clot, which has developed at the site of blockade (atherosclerosis) or developed and then moved to other parts of the body (arterial embolism)
• Haemorrhagic: a haemorrhagic stroke is caused by weak blood vessels that burst open. The escaping blood accumulates and compresses the surrounding nerve cells

Depending on the brain region affected, a stroke might lead to a vast variety of symptoms such as³:

• Inability to move the upper and/or lower limb on one side of the body (hemiplegia)
• Incapability to understand or formulate speech (aphasia)
• Visual disturbances
• Spasticity on one side of the body (spastic hemiplegia)

Symptoms can be:

• Transient: a transient ischaemic attack may last between a few seconds and hours. These events are an alert that should lead to an immediate consultation³
• Permanent: these symptoms usually improve over time, especially when an appropriate rehabilitation programme is set⁴

In the twelve months over 2022/23, 91,162 people in the UK were admitted to hospital due to stroke. It is estimated that 25% of the stroke survivors develop spasticity two weeks after a stroke episode. It is reported that 38% of people surviving their first stroke will experience spasticity at 12 months post-stroke.^5,6

Multiple sclerosis (MS) is a chronic autoimmune disease that causes inflammation in the central nervous system. This inflammation can damage myelin, the protective sheath that surrounds and insulates nerves (like the insulation around an electrical wire). When myelin is lost, nerves lose the ability to conduct electrical impulses to and from the brain, leading to various neurological symptoms.⁷

It was once thought that progression of disability in MS only happened after relapses (flare-ups). However, research now suggests that relapses and progression can occur together and that disability can gradually worsen over time, even without relapses. The symptoms of MS can vary between patients and over time in the same patient, reflecting its complex and changing nature.⁷

MS can affect any part of the central nervous system, i.e. the brain or the spinal cord. If the disorder affects the motor areas in the central nervous system, connections between the brain and the muscles are disturbed and this can lead to spasticity.⁸

Other frequent symptoms are⁷:

• Balance impairment
• Coordination difficulties
• Bladder dysfunction
• Visual impairment

Traumatic brain injury causes substantial disability and mortality, especially among children, adolescents, and young adults. It occurs when a sudden trauma damages the brain and disrupts normal brain function.^9,10

The main causes of traumatic brain injury are road traffic accidents, falls, sports-related impacts, and physical violence. In military settings, explosions and blast injuries are also significant causes. Brain damage can also be caused by¹¹:

• Oxygen deficiency
• Encephalitis: infection of the brain
• Meningitis: infection of the covering of the brain and spinal cord

The main causes of traumatic brain injury are road traffic accidents and falls.

Traumatic brain injury symptoms can impact individuals in physical, psychological, cognitive, emotional, and social ways. Upper motor neuron syndrome (UMNS) is a common complication in moderate or severe cases meaning the likelihood of epileptic seizures, cognitive decline and spasticity can be very high.^10,12

Traumatic brain injury results in the development of spasticity in up to 85% of those affected.¹²

Although well-protected by the vertebrae of the spinal column, the spinal cord can be damaged in many ways. Most spinal cord injuries occur as a result of road traffic accidents, sports injuries, physical altercations, or falls (the latter predominantly in elderly people).^13,14

A spinal cord injury can disrupt communication between the brain and the part of the spinal cord below the injury.¹⁵

Depending on the extent of damage, spasticity is a form of muscle overactivity that occurs when this happens.¹⁶

After spinal cord injury, 65% to 74% of patients are reported to have spasticity, and 35% to 45% of patients have spasticity that is troublesome or problematic.^17,18

Injuries to the spinal cord can cause loss of:

• Muscle function¹⁹
• Sensation in the body below the level of injury¹⁹
• Control of the bowels and bladder^13,15
• Normal sexual function¹⁵

Spinal cord injuries in the upper neck can cause difficulty breathing and may require the use of a breathing machine or ventilator.²⁰

Cerebral palsy is caused by damage to the motor control centres of the developing brain and can occur during pregnancy, childbirth, or postpartum, up to three years later.²¹

The damage to the motor control centre can have various causes such as²²:

• Accident during pregnancy
• Drug abuse by the pregnant mother
• Infections
• Birth malformation
• Abnormal brain development
• Arterial malformation

Cerebral palsy causes physical impairment as seen in the upper motor neuron syndrome, including spasticity²¹.

Spastic cerebral palsy is the most common type of cerebral palsy, with spasticity found in 70% of people with cerebral palsy aged 2 to 20 years⁵, resulting in stiff muscles and awkward movements.²¹ Among people with cerebral palsy and spasticity, quadriplegia is most common (in 33%), then hemiplegia (21%), diplegia (16%) and monoplegia (0.1%).⁵ Hemiplegic spastic cerebral palsy usually affects the arm and hand on one side of the body, but it can include the leg.²¹ Balance, posture and coordination can also be affected.²¹

¹Thibaut A, Chatelle C, Ziegler E, Bruno MA, Laureys S, Gosseries O. Spasticity after stroke: physiology, assessment and treatment. Brain Inj. 2013;27(10):1093-105. doi: 10.3109/02699052.2013.804202.

²Barthels D, Das H. Current advances in ischemic stroke research and therapies. Biochim Biophys Acta Mol Basis Dis. 2020 Apr 1;1866(4):165260. doi: 10.1016/j.bbadis.2018.09.012.

³National Institute of Neurological Disorders and Stroke (NINDS). April 2020. Post-stroke rehabilitation. NIH Publication No. 20-NS-4846. National Institutes of Health. Available at: https://catalog.ninds.nih.gov/sites/default/files/publications/post-stroke-rehabilitation.pdf [accessed September 2025].

⁴Grefkes C, Fink GR. Recovery from stroke: current concepts and future perspectives. Neurol Res Pract. 2020 Jun 16;2:17. doi: 10.1186/s42466-020-00060-6.

⁵https://www.strokeaudit.org/Documents/National/Clinical/Apr2022Mar2023/Apr2022Mar2023-AnnualReport.aspx [accessed September 2025]

⁶Bavikatte G, Subramanian G, Ashford S, Allison R, Hicklin D. Early Identification, Intervention and Management of Post-stroke Spasticity: Expert Consensus Recommendations. J Cent Nerv Syst Dis. 2021;13:11795735211036576. Published 2021 Sep 20. doi:10.1177/11795735211036576

⁷Portaccio E, Magyari M, Havrdova EK, Ruet A, Brochet B, Scalfari A, Di Filippo M, Tur C, Montalban X, Amato MP. Multiple sclerosis: emerging epidemiological trends and redefining the clinical course. Lancet Reg Health Eur. 2024 Aug 22;44:100977. doi: 10.1016/j.lanepe.2024.100977.

⁸Chang E, Ghosh N, Yanni D, Lee S, Alexandru D, Mozaffar T. A review of spasticity treatments: pharmacological and interventional approaches. Crit Rev Phys Rehabil Med. 2013;25(1-2):11-22. doi: 10.1615/CritRevPhysRehabilMed.2013007945.

⁹Kundu S, Singh S. What happens in TBI? A wide talk on animal models and future perspective. Curr Neuropharmacol. 2023;21(5):1139-1164. doi: 10.2174/1570159X20666220706094248.

¹⁰Maas AIR, Menon DK, Manley GT, Abrams M, Åkerlund C, Andelic N, et al. Traumatic brain injury: progress and challenges in prevention, clinical care, and research. Lancet Neurol. 2022 Nov;21(11):1004-1060. doi: 10.1016/S1474-4422(22)00309-X.

¹¹National Institute of Neurological Disorders and Stroke (NINDS). 2024a. Traumatic brain injury (TBI). Last reviewed 15 October 2024. National Institutes of Health. Available at: https://www.ninds.nih.gov/health-information/disorders/traumatic-brain-injury-tbi#toc-how-does-tbi-affect-the-brain [accessed September 2025].

¹²Enslin JMN, Rohlwink UK, Figaji A. Management of Spasticity After Traumatic Brain Injury in Children. Front Neurol. 2020 Feb 21;11:126.

¹³Ahuja CS, Wilson JR, Nori S, Kotter MRN, Druschel C, Curt A, Fehlings MG. Traumatic spinal cord injury. Nat Rev Dis Primers. 2017 Apr 27;3:17018. doi: 10.1038/nrdp.2017.18.

¹⁴National Institute of Neurological Disorders and Stroke (NINDS). 2024c. Spinal cord injury. Last reviewed 19 July 2024. National Institutes of Health. Available at: https://www.ninds.nih.gov/health-information/disorders/spinal-cord-injury [accessed September 2025].

¹⁵Awad A, Levi R, Waller M, Westling G, Lindgren L, Eriksson J. Preserved somatosensory conduction in complete spinal cord injury: discomplete SCI. Clin Neurophysiol. 2020 May;131(5):1059-1067. doi: 10.1016/j.clinph.2020.01.017.

¹⁶Trompetto C, Marinelli L, Mori L, Pelosin E, Currà A, Molfetta L, Abbruzzese G. Pathophysiology of spasticity: implications for neurorehabilitation. Biomed Res Int. 2014;2014:354906. doi: 10.1155/2014/354906.

¹⁷Holtz KA, Lipson R, Noonan VK, Kwon BK, Mills PB. Prevalence and Effect of Problematic Spasticity After Traumatic Spinal Cord Injury. Arch Phys Med Rehabil. 2017 Jun;98(6):1132-8.

¹⁸Skoog B., Jakobsson K.E. Prevalence of Spasticity and Below-Level Neuropathic Pain Related to Spinal Cord Injury Level and Damage to the Lower Spinal Segments. J. Rehabil. Med. Clin. Commun. 2020;3:1000039. doi: 10.2340/20030711-1000039.

¹⁹Butler Forslund E, Truong MTN, Wang R, Seiger Å, Gutierrez-Farewik EM. A protocol for comprehensive analysis of gait in individuals with incomplete spinal cord injury. Methods Protoc. 2024 May 4;7(3):39. doi: 10.3390/mps7030039.

²⁰Satkunendrarajah K, Karadimas SK, Fehlings MG. Spinal cord injury and degenerative cervical myelopathy. Handb Clin Neurol. 2022;189:241-257. doi: 10.1016/B978-0-323-91532-8.00006-9.

²¹Pulgar et al. Prevalence, Patterns, and Cost of Care for Children with Cerebral Palsy Enrolled in Medicaid Managed Care. J Manag Care Spec Pharm 2019 Jul;25(7):817-822. https://pubmed.ncbi.nlm.nih.gov/31232210/ [accessed September 2025]

²²National Institute of Neurological Disorders and Stroke (NINDS). 2024. Cerebral Palsy. Last reviewed 19 July 2024. National Institutes of Health. Available at: https://www.ninds.nih.gov/health-information/disorders/cerebral-palsy# [accessed September 2025].