While chronic progressive brachial monoplegia is uncommon, syringomyelia and tumors of the cervical cord or brachial plexus may be the cause. The onset of brachial plexus paralysis is usually explosive where pain is the initial feature. Pain localizes to the shoulder but may be more diffuse, or could be limited to the lower arm. Pain is severe and often described as sharp, stabbing, throbbing, or aching. The duration of pain, which is constant, varies from a span of several hours to 3 weeks. As the pain subsides, weakness usually appears. In addition, chronicle progressive weakness of one leg suggests a tumor of the spinal cord of the lumbar plexus. Fever is often the first symptom of lumbar plexus paralysis, followed by pain in one or both legs. The pain has an abrupt onset and may occur in a femoral or sciatic distribution. Weakness may develop concurrently with pain or be delayed for as long as 3 weeks. Furthermore, a monomeric form of spinal muscular atrophy, affecting only one leg or arm, should be considered when progressive weakness is not accompanied by sensory loss. Causes
Some potential causes of monoplegia are listed below.
Iridodialysis is a localized separation or tearing away of the iris from its attachment to the ciliary body. Symptoms and signs
Those with small iridodialyses may be asymptomatic and require no treatment, but those with larger dialyses may have corectopia or polycoria and experience monocular diplopia, glare, or photophobia. Iridodialyses often accompany angle recession and may cause glaucoma or hyphema. Hypotony may also occur. Complications
Those with traumatic iridodialyses (particularly by blunt trauma) are at high risk for angle recession, which may cause glaucoma. This is typically seen about 100 days after the injury, and as such is sometimes  called "100-day glaucoma". Medical or surgical treatment to control the IOP may be required if glaucoma is present. Soft, opaque contact lenses may be used to improve cosmesis and reduce the perception of double vision. Causes
Iridodialyses are usually caused by blunt trauma to the eye, but may also be caused by penetrating eye injuries. An iridodialysis may be an iatrogenic complication of any intraocular surgery and at one time they were created intentionally as part of intracapsular cataract extraction. Iridodialyses have been reported to have occurred from boxing, airbag deployments, high-pressure water jets, elastic bungee cords, bottle caps opened under pressure, water balloons, fireworks, and various types of balls. Treatment
Iridodialysis causing an associated hyphema has to be carefully managed, and recurrent bleeds should be prevented by strict avoidance of all sporting activities. Management typically involves observation and bed rest.