Author:
Editor(s):
Updated:
ULY CLINIC
ULY CLINIC
12 Septemba 2025, 01:33:39
Muscle Flaccidity (Muscle Hypotonicity)
Muscle flaccidity is characterized by profound weakness, soft muscles, decreased resistance to movement, and increased joint mobility, often resulting in an abnormally large range of motion (ROM). It arises from disrupted muscle innervation and may affect a single limb or muscle group or be generalized over the entire body. Onset can be acute, as in trauma, or chronic, as in neurologic diseases.
Emergency interventions
Trauma: Stabilize the cervical spine.
Respiratory assessment: Quickly check for dyspnea, shallow respirations, nasal flaring, cyanosis, and decreased oxygen saturation.
Oxygen therapy: Administer via nasal cannula or mask; intubation and mechanical ventilation may be required in severe cases.
History and Physical Examination
History:
Determine onset, duration, and precipitating factors.
Ask about associated symptoms, including weakness, other muscle changes, and sensory loss or paresthesia.
Physical Examination:
Examine muscle atrophy, which suggests a chronic condition.
Test muscle strength.
Assess deep tendon reflexes (DTRs) in all limbs.
Medical causes
Condition | Features | Associated Findings |
Amyotrophic lateral sclerosis (ALS) | Progressive generalized flaccidity | Fasciculations, hyperactive DTRs, slight leg spasticity, dysphagia, dysarthria, drooling, respiratory insufficiency, depression |
Brain lesions (frontal/parietal lobes) | Contralateral flaccidity | Weakness/paralysis, eventual spasticity, hyperactive DTRs, positive Babinski, sensory loss (proprioception, stereognosis, graphesthesia, thermanesthesia) |
Guillain-Barré syndrome | Symmetrical, ascending flaccidity | Sensory loss/paresthesia, absent DTRs, autonomic instability (tachy/bradycardia, BP fluctuations), dysphagia, facial diplegia, respiratory failure |
Huntington’s disease | Flaccidity with choreiform movements | Progressive cognitive decline/dementia, poor balance, dysarthria, dysphagia, respiratory impairment, incontinence |
Muscle disease (myopathies, muscular dystrophies) | Flaccid weakness | Progressive loss of muscle function |
Peripheral nerve trauma | Flaccidity, paralysis, sensory/reflex loss | Depends on nerve distribution |
Peripheral neuropathy | Distal limb flaccidity, usually legs | Paresthesia, hyperesthesia, anesthesia, burning pain, anhidrosis, loss of vibration sense, hypo/absent DTRs |
Seizure disorder | Transient generalized flaccidity post-tonic-clonic seizure | Brief syncope or weakness |
Spinal cord injury | Acute flaccidity (spinal shock) | Paralysis below injury, absent DTRs, sensory loss, hypotension, bowel/bladder dysfunction, respiratory compromise (C1–C5), impotence/priapism |
Special considerations
Perform regular passive ROM exercises to maintain joint mobility and circulation.
Reposition patients with generalized flaccidity every 2 hours to prevent pressure ulcers.
Pad bony prominences and prevent thermal injuries during bathing.
Support isolated flaccid limbs with slings or splints.
Ensure patient safety, teach assistive device use, and consult a physician or occupational therapist for individualized therapy.
Prepare for diagnostic tests: cranial/spinal X-rays, CT scans, EMG.
Patient counseling
Educate the patient on proper use of assistive devices.
Review the exercise regimen and emphasize safety measures.
Pediatric pointers
Causes in children include:
Myelomeningocele
Lowe’s disease
Werdnig-Hoffmann disease
Muscular dystrophy
Infants with generalized flaccidity may adopt a froglike posture, with hips and knees abducted.
References
Ageno W, Agnelli G, Checchia G, Cimminiello C, Paciaroni M, Palareti G, Testa S, et al. Prevention of venous thromboembolism in immobilized neurological patients: Guidelines of the Italian Society for Haemostasis and Thrombosis (SISET). Thromb Res. 2009;124(5):26–31.
van Hedel HJ, Dietz V. Rehabilitation of locomotion after spinal cord injury. Restor Neurol Neurosci. 2010;28(1):123–134.