From the Guidelines
Leg monoparesis is most commonly caused by conditions affecting the nervous system, with stroke, spinal cord lesions, peripheral nerve injuries, and neuromuscular junction disorders being among the most prevalent causes. The diagnosis of leg monoparesis requires a thorough neurological examination to determine the pattern of weakness and associated symptoms. Some key points to consider in the diagnosis and management of leg monoparesis include:
- A thorough history and physical examination to identify the underlying cause of leg monoparesis, including assessment of lower extremity pulses and evaluation for signs of peripheral neuropathy 1.
- Imaging studies such as MRI of the brain or spine, nerve conduction studies, or electromyography may be necessary to confirm the diagnosis and guide treatment 1.
- Treatment depends entirely on the underlying cause, ranging from physical therapy and medication management for inflammatory conditions to surgical intervention for compressive lesions 1.
- Early diagnosis is crucial as some causes like stroke require immediate intervention to prevent permanent disability 1.
- The prognosis varies significantly based on the underlying etiology, with some conditions being reversible while others may lead to progressive weakness despite treatment 1. It is also important to consider alternative diagnoses for leg pain or claudication not related to peripheral artery disease (PAD), such as hip arthritis, foot/ankle arthritis, nerve root compression, spinal stenosis, and symptomatic popliteal (Baker’s) cyst 1. In patients with confirmed diagnosis of PAD, it is essential to assess the risk of subclavian artery stenosis and to measure blood pressure in both arms 1. Overall, a comprehensive approach to diagnosis and management is necessary to improve outcomes in patients with leg monoparesis.
From the Research
Causes of Leg Monoparesis
- Ischemic stroke is a common cause of leg monoparesis, with cortical infarctions of the precentral knob and the anterior cerebral artery territory being the most commonly reported lesion sites 2
- Spinal cavernoma is a rare cause of acute monoparesis, with intramedullary cavernoma being a possible cause of leg monoparesis 3
- Peripheral and cranial nerve lesions can also cause monoparesis, including leg monoparesis 4
- Isolated monoparesis following stroke can be caused by small artery disease or a small hemorrhage, with most ischemic lesions occurring in the deep territory of the middle cerebral artery, the corona radiate, or the centrum semiovale 5
- Spinal cord infarction is a rare cause of leg monoparesis, accounting for 0.3-1% of all strokes, and is often associated with severe deficits but good functional improvement 6
Characteristics of Leg Monoparesis
- Leg monoparesis can present with pure motor deficit, without accompanying cranial or sensory dysfunction 2
- Distal-dominant weakness and the absence of pyramidal signs are commonly observed in leg monoparesis due to ischemic stroke 2
- Moderate spasticity and brisk tendon reflexes can be present in leg monoparesis caused by spinal cavernoma 3
- Leg monoparesis can be a rare symptom in stroke patients, often caused by small artery disease or a small hemorrhage 5
Diagnosis and Prognosis of Leg Monoparesis
- Diffusion-weighted imaging is the most useful tool for diagnosing pure motor monoparesis due to ischemic stroke 2
- Spinal MRI can reveal intramedullary lesions consistent with cavernoma in cases of leg monoparesis caused by spinal cavernoma 3
- The overall prognosis of leg monoparesis is generally good, with most patients showing good functional improvement 2, 6