Monoplegia is paralysis of a single limb, usually an arm. Common symptoms associated with monoplegic patients are weakness, numbness, and pain in the affected limb. Monoplegia is a type of paralysis that falls under hemiplegia. While hemiplegia is paralysis of half of the body, monoplegia is localized to a single limb or to a specific region of the body. Monoplegia of the upper limb is sometimes referred to as brachial monoplegia, and that of the lower limb is called crural monoplegia. Monoplegia in the lower extremities is not as common of an occurrence as in the upper extremities. Monoparesis is a similar, but less severe, condition because one limb is very weak, not paralyzed. For more information, see paresis. Many conditions that cause paraplegia or quadriplegia begin as monoplegia. Thus, the diagnosis of spinal paraplegia must also be consulted. In addition, multiple cerebral disorders that cause hemiplegia may begin as monoplegia. Monoplegia is also frequently associated with, and considered to be the mildest form of, cerebral palsy. Signs and symptoms
There are a number of symptoms associated with monoplegia. Curling of the hands or stiffness of the feet, weakness, spasticity, numbness, paralysis, pain in the affected limb, headaches, and shoulder pain are all considered to be symptoms of monoplegia. Patients of monoplegia typically feel symptoms of weakness and loss of sensation in the affected extremity, usually an arm. Despite these symptoms, the extremity with paralysis continues to maintain a strong pulse.
Cerebral palsy
Direct physical trauma to the affected limb
Central nervous mass lesion, including tumor, hematoma, or abscess
Complicated migraine
Epilepsy
Head or spinal trauma
Hereditary brachial neuritis
Hereditary neuropathy with liability to pressure palsy
Neonatal brachial plexus paralysis
Neuropathy
Plexopathy
Traumatic peroneal neuropathy
Vaccine-associated paralytic poliomyelitis
Hemiparetic seizures
Monomeric spinal muscular atrophy
StrokeSpecifically, monoplegia in the lower extremities is typically caused by Brown Sequard syndrome and hematomas in the frontoparietal cortex near the middle that could produce a deficit such as this, but this is a very uncommon occurrence. Mechanism
In monoplegia, the spine and the proximal portion of nerves are usually the abnormal sites of limb weakness. Monoplegia resulting from upper extremity impairments following a stroke occurs due to direct damage to the primary motor cortex, primary somatosensory cortex, secondary sensorimotor cortex, sensorimotor cortical areas, subcortical structures, and/or the corticospinal tract. It is often found that impairments following stroke are either caused by damage to the same or adjacent neurological structures. A combination of these impairments is more likely than just one in isolation. Damage to the corticospinal system results in an inability to activate muscles with enough force or in a coordinated manner, which can lead to paresis, loss of fractional movement, and abnormal muscle tone. Damage to the somatosensory cortical areas causes loss of somatosensation which results in an impaired ability to monitor movement.Considering monoplegia as it relates to cerebral palsy, in premature infants, the most common cause of cerebral palsy is periventricular hemorrhagic infarction. In term infants, the underlying causes are often cerebral malformations, cerebral infarction, and intracerebral hemorrhage.