Flaccid hemiplegia is paralysis on one side of the body where the affected muscles are limp and without tone, rather than stiff or tight. It most commonly occurs immediately after a stroke, representing the earliest phase of motor loss before the muscles transition to other states. The affected arm, leg, or both hang loosely, cannot be moved voluntarily, and show little or no resistance when someone else moves them.
How Flaccid Hemiplegia Differs From Spastic Hemiplegia
The word “flaccid” describes the specific quality of the paralysis. In flaccid hemiplegia, the muscles on the affected side are soft and floppy. Reflexes are reduced or absent, and the limbs feel heavy and limp. This is the opposite of spastic hemiplegia, where the muscles become abnormally stiff, reflexes are exaggerated, and the limbs resist being moved.
After a stroke, most people pass through both states in sequence. The flaccid phase comes first. Spasticity, a velocity-dependent tightness where muscles resist quick stretching, typically emerges between one and six weeks after the initial brain injury. The progression from flaccid to spastic reflects the nervous system reorganizing after damage, not necessarily improvement or worsening on its own.
A widely used framework called the Brunnstrom stages maps this progression across seven stages. Stage 1 is pure flaccidity: no voluntary movement, no muscle tone. Stages 2 through 5 involve the gradual appearance and then decrease of spasticity alongside returning voluntary control. Stages 6 and 7 represent recovery, with spasticity disappearing and coordinated movement returning. Not everyone progresses through all seven stages, and some people remain in the flaccid phase for an extended period.
What Causes It
Flaccid hemiplegia results from damage to the brain or spinal cord that disrupts the signals traveling from the motor areas of the brain down to the muscles. The most common cause is stroke, either from a blocked blood vessel (ischemic stroke) or bleeding in the brain (hemorrhagic stroke). In the immediate aftermath, the brain’s motor pathways essentially go quiet on the affected side, producing flaccidity.
Other causes include traumatic brain injuries and concussions, spinal cord injuries, brain tumors, bleeding between the brain and skull (epidural or subdural hematomas), and infections that affect the nervous system such as encephalitis or meningitis. Autoimmune conditions like multiple sclerosis can also produce hemiplegia. In rarer cases, hemiplegic migraines cause temporary one-sided paralysis.
Spinal cord injuries produce a particularly dramatic version of flaccidity called spinal shock, where the body below the injury becomes acutely paralyzed with very low muscle tone and absent reflexes. This phase can last from days to weeks before spasticity develops. The flaccid period tends to be more pronounced with spinal cord lesions than with injuries to the brain itself.
Why Some People Stay Flaccid Longer
For most stroke survivors, flaccidity is temporary. But in some cases, the muscles remain limp for months. Research involving brain imaging of 42 stroke patients found that prolonged flaccidity was closely linked to damage in a deep brain structure called the lentiform nucleus, part of a cluster of regions involved in motor control. Patients who stayed flaccid had significantly reduced blood flow in several connected brain areas, including the thalamus and the opposite side of the cerebellum, even when those regions appeared structurally intact on scans.
This suggests that prolonged flaccidity isn’t just about the size of the stroke. It reflects widespread disruption in the brain’s motor circuits, particularly two loops that coordinate movement: one running through the deep brain structures and back to the cortex, and another routing through the brainstem and cerebellum. When both loops are severely affected, the flaccid state persists, and the motor deficit tends to be greater.
Shoulder Subluxation: A Major Complication
One of the most significant risks during the flaccid phase is shoulder subluxation, where the arm bone partially slides out of the shoulder socket because the surrounding muscles are too weak to hold it in place. The reported prevalence in hemiplegic patients ranges from 17% to 81%, with one study finding a rate of 51%. It can be painful and, if not managed carefully, can lead to rotator cuff injuries and other soft tissue damage.
During rehabilitation, therapists take specific precautions to protect the flaccid shoulder. Movements that lift the arm out to the side beyond about 60 degrees are avoided because they risk further injury. External rotation, where the arm twists outward, is also limited in patients with subluxation to prevent damage to the tendons and cartilage around the joint. Slings, lap trays, and careful positioning help support the arm when the patient is sitting or standing. Patients are also taught to protect their shoulder during everyday activities like dressing and transfers.
How It’s Diagnosed
Diagnosis starts with a physical examination. A clinician will test muscle strength on both sides of the body, check muscle tone by moving the limbs passively, and test reflexes with a reflex hammer. In flaccid hemiplegia, the affected side shows marked weakness or no movement, very low or absent muscle tone, and diminished reflexes.
Imaging is a critical next step. An MRI of the brain and spinal cord can reveal the location and extent of the damage causing the paralysis. For stroke, CT scans are often done first in the emergency setting because they’re faster. Nerve conduction studies, which measure how well electrical impulses travel along nerves, help determine whether the problem originates in the brain, spinal cord, or peripheral nerves. In some cases, a lumbar puncture is performed to check the cerebrospinal fluid for signs of infection or inflammation.
Rehabilitation During the Flaccid Phase
Therapy during flaccidity focuses on maintaining what the muscles and joints have while waiting for motor signals to return. Because the muscles can’t contract on their own, a therapist moves the affected limbs through their full range of motion passively. This prevents joints from stiffening, keeps soft tissues from shortening, and maintains circulation. Stretching the fingers, wrist, and larger joints to their maximum pain-free range is a routine part of treatment.
Electrical stimulation is one of the most commonly used interventions for flaccid muscles. Small electrodes placed on the skin deliver controlled pulses that cause the muscle to contract, essentially substituting for the missing brain signal. This serves multiple purposes: it helps maintain muscle bulk, improves blood flow, and may support the brain’s ability to relearn motor control. Functional electrical stimulation takes this a step further by timing the muscle contractions to occur during a meaningful task, like grasping an object or lifting the wrist.
Splints and positioning devices are used to keep joints in proper alignment. A flaccid hand, for instance, tends to rest in a curled position that can lead to permanent tightness if the fingers aren’t regularly straightened and supported. Sensory stimulation techniques, including stroking, tapping, and guided movement of the affected limbs, aim to reactivate the brain’s awareness of the paralyzed side. Even before voluntary movement returns, these approaches help maintain the neural connections between the brain and the affected muscles.
Recovery timelines vary widely. Some people begin to show voluntary muscle contractions within days, while others remain in the flaccid stage for weeks or months. Earlier onset of voluntary movement generally predicts better long-term recovery, though gains can continue well beyond the initial months with sustained rehabilitation.