Many conditions can cause leg pain and weakness. According to the University of Maryland Medical Center, leg pain can be caused by overuse injuries, inflammatory diseases, lower extremity trauma and certain medical conditions. In some cases, leg pain is accompanied by lower extremity weakness. Simultaneous leg pain and weakness may signal a serious underlying condition, especially if the weakness develops rapidly. A person may first notice leg weakness when climbing stairs or performing other activities of daily living.
Diabetic neuropathy can cause leg pain and weakness. According to the National Institute of Diabetes and Digestive and Kidney Diseases, or NIDDK, diabetic neuropathy is a nerve-related disorder caused by diabetes. Approximately 60 to 70 percent of diabetics develop some degree of neuropathy, or nerve damage. Nerve damage can occur in every organ system in the body, including the gut, heart and reproductive organs. Diabetic neuropathy can also occur in the upper and lower extremities, causing pain and weakness in the arms or legs. Common signs and symptoms associated with diabetic neuropathy include pain; numbness and tingling in the toes, feet and legs; lower extremity atrophy, or muscle wasting and weakness; indigestion; nausea and vomiting; problems with urination; and dizziness when sitting up from a lying position. NIDDK states that loss of sensation in the extremities is the most common form of diabetic neuropathy.
Lumbar Disc Herniation
A lumbar, or lower back, disc herniation can cause leg pain and weakness. The University of Maryland Medical Center states that lumbar disc herniations---a protrusion of part of the spinal disc into the spinal canal or intervertebral foramen---are most common among young and middle-aged adults. Older individuals rarely experience a herniated disc because degenerative changes that develop in the spine with aging make disc herniations in this population unlikely. A herniated disc may compress or irritate a spinal nerve root---an offshoot of the spinal cord---as it exits the spinal column through the intervertebral foramen or hole between two lumbar vertebrae or spinal bones. Most disc herniations cause symptoms on one side of the body only. Common signs and symptoms associated with a lumbar disc herniation include lower back and leg pain, numbness and tingling that travels down the back of the affected-side thigh, lower extremity muscle weakness, and reduced deep tendon reflexes.
Multiple sclerosis can cause leg pain and weakness. According to the National Institute of Neurological Disorders and Stroke, or NINDS, multiple sclerosis is an unpredictable nervous system disease that can range from mild to debilitating, depending on the level of disruption between the brain and other parts of the body. It's believed that multiple sclerosis is an autoimmune condition in which the body senses the myelin sheath---the fatty coating surrounding nerves---as foreign and attacks it. Destruction of the myelin sheath disrupts impulses to and from the brain. NINDS states that multiple sclerosis symptoms usually manifest between the ages of 20 and 40. Common signs and symptoms associated with multiple sclerosis include pain, numbness, tingling and weakness in one or more of the extremities, vision problems, tremors, lack of coordination, dizziness, and fatigue.