What does weakness in the legs mean?
True muscle weakness means you can't develop the strength you normally need, for example to stand up, walk on your toes, or lift your foot. Pain and fear can also limit strength without nerve damage.
A feeling of heavy legs can be due to fatigue, circulation, medication or fitness, so the healthcare provider will test the strength of different muscle groups rather than just relying on sensation.
Weakness may occur along with numbness in the leg or pain that radiates down the leg.
Possible causes of leg weakness
Stroke often causes sudden one-sided weakness and can affect the face, arm, speech or vision. Affecting the spinal cord can cause weakness in both legs and sometimes sensory or bladder symptoms.
Herniated discs and spinal stenosis can affect nerve roots and cause pain, numbness, and weakness. Polyneuropathy often begins distally in the feet and progresses gradually.
Muscle disease, electrolyte imbalance, thyroid disease, medications, and general illness can also reduce strength. Circulatory problems are more likely to cause pain and fatigue when walking than isolated muscle weakness.
When is leg weakness acute?
Call 112 if you experience sudden weakness in one leg or one side of your body, especially with drooping corners of your mouth, speech problems, loss of vision, severe headache or dizziness.
Seek emergency care if you have weakness in both legs along with decreased sensation around your lower abdomen, inability to urinate, urine or stool leakage, or rapidly increasing back pain.
Rapid assessment is also needed if the weakness progresses upward, affects breathing, occurs after trauma, or is combined with fever and severe back pain.
Call 112 for sudden one-sided weakness or other stroke symptoms. Seek emergency care for leg weakness with bladder dysfunction or loss of sensation in the lower abdomen.
How is bone weakness investigated?
The neurological examination tests strength, reflexes, sensation, coordination, and gait. The classification helps to differentiate between brain, spinal cord, nerve root, peripheral nerve, and muscle involvement.
Blood tests can assess blood sugar, salts, thyroid, vitamin deficiencies, inflammation, and muscle enzymes. Medications and alcohol habits also need to be reviewed.
Nerve conduction studies and EMG can assess peripheral nerves and muscles. If vascular problems are suspected, the circulation is examined separately.
When is MRI brain or MRI spine used?
MRI brain used when symptoms and examination point to the brain, for example in certain central neurological conditions. Acute suspected stroke, on the other hand, is assessed through emergency medical care and often CT first.
MRI of the spine is used when there is suspected involvement of the spinal cord, nerve roots or other structures in the back. The correct spinal section is chosen based on the symptom pattern.
MRI of the brain is not automatically correct for all bone symptoms. Clinical localization determines which examination can provide answers.
How can you describe the weakness clearly?
Note if you have difficulty getting up from a chair, climbing stairs, walking on your heels or toes, or if your foot drags. Describe whether one or both legs are affected and how quickly it developed.
Document numbness, back pain, falls, vision or speech problems, and changes in urinary and bowel function. These details can determine the urgency of the situation.
Avoid driving or walking without support if your leg suddenly becomes weak. Seek emergency help instead of trying to test your limits yourself.