Muscle flaccidity [Muscle hypotonicity]

Flaccid muscles are profoundly weak and soft, with decreased resistance to movement, increased mobility, and greater than normal range of motion. The result of disrupted muscle innervation, flaccidity can be localized to a limb or muscle group or generalized over the entire body. Its onset may be acute, as in trauma, or chronic, as in neurologic disease.

Emergency Interventions

If the patient’s muscle flaccidity results from trauma, make sure his cervical spine has been stabilized. Quickly determine his respiratory status. If you note signs and symptoms of respiratory insufficiency—dyspnea, shallow respirations, nasal flaring, cyanosis, and decreased oxygen saturation—administer oxygen by nasal cannula or mask. Intubation and mechanical ventilation may be necessary.

History and physical examination

If the patient isn’t in distress, ask about the onset and duration of muscle flaccidity and any precipitating factors. Ask about associated symptoms, notably weakness, other muscle changes, and sensory loss or paresthesia.

Examine the affected muscles for atrophy, which indicates a chronic problem. Test muscle strength, and check deep tendon reflexes in all limbs.

Medical causes

Amyotrophic lateral sclerosis

Progressive muscle weakness and paralysis are accompanied by generalized flaccidity. Typically, these effects begin in one hand, spread to the arm, and then develop in the other hand and arm. Eventually, they spread to the trunk, neck, tongue, larynx, pharynx, and legs; progressive respiratory muscle weakness leads to respiratory insufficiency. Other findings include muscle cramps and coarse fasciculations, hyperactive deep tendon reflexes, slight leg muscle spasticity, dysphagia, dysarthria, excessive drooling, and depression.

Brain lesions

Frontal and parietal lobe lesions may cause contralateral flaccidity, weakness or paralysis, and eventually, spasticity and possibly contractures. Other findings include hyperactive deep tendon reflexes, positive Babinski’s sign, loss of proprioception, stereognosis, graphesthesia, anesthesia, and thermanesthesia.

Cerebellar disease

With this disease, generalized muscle flaccidity or hypotonia is accompanied by ataxia, dysmetria, intention tremor, slight muscle weakness, fatigue, and dysarthria.

Guillain-Barré syndrome

This disorder causes muscle flaccidity. Progression is typically symmetrical and ascending, moving from the feet to the arms and facial nerves within 24 to 72 hours of onset. Associated findings include sensory loss or paresthesia, absent deep tendon reflexes, tachycardia (or, less often, bradycardia), fluctuating hypertension and orthostatic hypotension, diaphoresis, incontinence, dysphagia, dysarthria, hypernasality, and facial diplegia. Weakness may progress to total motor paralysis and respiratory failure.

Huntington’s disease

Besides flaccidity, progressive mental status changes up to and including dementia and choreiform movements are major symptoms. Others include poor balance, hesitant or explosive speech, dysphagia, impaired respirations, and incontinence.

Muscle disease

Muscle weakness and flaccidity are features of myopathies and muscular dystrophies.

Peripheral nerve trauma

Flaccidity, paralysis, and loss of sensation and reflexes in the innervated area can occur.

Peripheral neuropathy

Flaccidity usually occurs in the legs as a result of chronic progressive muscle weakness and paralysis. It may also cause mild-to-sharp burning pain, glossy red skin, anhidrosis, and loss of vibration sensation. Paresthesia, hyperesthesia, or anesthesia may affect the hands and feet. Deep tendon reflexes may be hypoactive or absent.

Poliomyelitis

Damage to the anterior horn cells in the spinal cord and brain stem causes flaccid weakness and loss of reflexes. The large, proximal muscles of the limbs are most commonly affected.

Seizure disorder

Brief periods of syncope and generalized flaccidity commonly follow a generalized tonic-clonic seizure.

Spinal cord injury

Spinal shock can result in acute muscle flaccidity or spasticity below the level of injury. Associated signs and symptoms also occur below the level of injury and may include paralysis; absent deep tendon reflexes; analgesia; thermanesthesia; loss of proprioception and vibration, touch, and pressure sensation; and anhidrosis (usually unilateral). Hypotension, bowel and bladder dysfunction, and impotence or priapism may also occur. Injury in the C1 to C5 region can produce respiratory paralysis and bradycardia.

Special considerations

Provide regular, systematic, passive range-of-motion exercises to preserve joint mobility and to increase circulation. Reposition a patient with generalized flaccidity every 2 hours to protect him from skin breakdown. Pad bony prominences and other pressure points, and prevent thermal injury by testing bath water yourself before the patient bathes. Treat isolated flaccidity by supporting the affected limb in a sling or with a splint. Ensure patient safety and reduce the risk of falls by introducing assistive devices and their proper use. Consult a physician and occupational therapist to formulate a personalized therapy regimen and foster independence.

Prepare the patient for diagnostic tests, such as cranial and spinal X-rays, computed tomography scans, and electromyography.

Pediatric pointers

Pediatric causes of muscle flaccidity include myelomeningocele, Lowe’s disease, Werdnig-Hoffmann disease, and muscular dystrophy. An infant or young child with generalized flaccidity may lie in a froglike position, with his hips and knees abducted.

Book Source Details

• Book Title: Professional Guide to Signs & Symptoms (Fifth Edition)
• Author(s): Springhouse
• Year of Publication: 2006
• Copyright Details: Professional Guide to Signs & Symptoms (Fifth Edition), Copyright © 2006 Lippincott Williams & Wilkins.

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Copyright Details: Professional Guide to Signs & Symptoms (Fifth Edition), Copyright © 2008 Williams & Wilkins.

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More About This Book: Title: Professional Guide to Signs & Symptoms (Fifth Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2006 ISBN: 1-58255-510-9

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