What is Foot Drop in Obstetrics?
While it may seem that anesthesia during childbirth could be the cause of certain nerve-related problems, it’s actually the processes of pregnancy and labor that most often lead to these issues. These nerve injuries, also called obstetric palsies, are in fact more common than those caused by regional anesthesia administered for pain relief. It’s important to understand where
nerves are located in relation to surrounding physical structures in the body to pinpoint the location of the nerve injury, figure out how it appears as a neurological malfunction, and assess available treatment options.
Foot drop is a type of obstetric palsy. It was first identified in 1838 and can significantly affect your quality of life if not recognized and treated properly. Foot drop can be caused by issues in three areas: the lumbar radiculopathy (nerves in your lower spine), the lumbosacral (LS) plexopathy (nerve network in your lower spine), or the common fibular (CF) neuropathy (nerve in your leg). A combination of careful nerve checks, MRI scans, and tests measuring electrical activity in muscles and nerves help determine the site of the nerve injury.
Foot drop mainly surfaces as a lack of ability to lift the foot upwards (dorsiflexion) and turn the sole of the foot outward (eversion) at the ankle. This can cause a slapping sound when the affected foot hits the ground. To avoid dragging the foot on the ground, one might lift it higher than usual, leading to a distinctive stepping pattern. Other possible symptoms can include tingling, reduced feeling, numbness, muscle weakness, shrinkage, and diminished or loss of deep tendon reflexes.
Foot drop is usually seen to affect only one foot, except in the case of common fibular neuropathy, which may affect both feet. This paper aims to explain the individual reasons behind each type of obstetric foot drop and to clarify related clinical anatomy to guide doctors in making correct diagnoses and deciding appropriate treatment for such nerve injuries.
Let’s explore some anatomy. The lumbosacral (LS) plexus is located in the psoas muscles (major muscles in your lower back) and is formed by nerve roots from L1-S4 (sections of your lower spine), controlling sensation and movement of the pelvis, thigh, leg, and foot. Each mixed spinal nerve splits off into two roots: ventral and dorsal. Damage to these roots can cause loss of sensation or muscle weakness, respectively. Of these roots, the L5 and S1 are of particular importance in relation to obstetric nerve injuries.
The lumbosacral trunk, formed by nerve roots L4 and L5, runs down in the area of the sacral ala (part of your pelvis) where it might be injured by the descending fetal head during childbirth. Injury to the L5 component of the lumbosacral trunk can be enough to cause foot drop.
The nerves from the lumbosacral plexus branch out to form distinct peripheral nerves associated with the lower limbs. The upper plexus gives rise to nerves that control the abdomen and the inner and frontal thigh muscles, while the lower part sends nerve supply to muscles of the buttock, posterior thigh, and the large sciatic nerve, which extends down the back of the leg.
The common fibular nerve arises from the sciatic nerve and passes over the fibula (the outer leg bone), where it divides into the superficial and deep fibular nerves. Both these nerves supply to muscles and skin surface areas in the leg, controlling movements like lifting the foot upwards (dorsiflexion) and turning the sole of the foot outwards (eversion). Damage to the common fibular nerve or the deep fibular nerve can result in foot drop.
What Causes Foot Drop in Obstetrics?
Foot drop occurs when there is pressure or damage on the nerves that control the ability to lift the front part of your foot. This can happen during childbirth, due to the baby’s position or the use of tools like forceps. It can also be caused by specific body positions like laying on your back with your legs raised (dorsolateral lithotomy) or due to a herniated disc in the lower spine.
Radiculopathy is a condition where one or more nerves don’t work properly due to being damaged or disturbed. This is one of the less common causes of foot drop in women after childbirth and is caused by a herniated disc. This issue often presents itself days or months after giving birth. To diagnose this condition, doctors use tests like magnetic resonance imaging (MRI) and electromyography (EMG), which help to confirm if there are any problems with your nerves and muscles.
Neural issues can also arise from damage to what’s known as the lumbosacral plexus, a network of intersecting nerves in the lumbar region of the body. In childbirth, this can happen when the baby’s head pushes down into the pelvis. Symptoms of this kind of damage could include difficulties controlling your hip, groin, or leg muscles, in addition to foot drop.
The common fibular nerve is a nerve located in the lower leg that is responsible for controlling muscles which lift your foot. If this nerve is compressed or damaged during childbirth, it can lead to foot drop. This could be due to the patient holding their legs in a certain way during labor, such as holding the knees tightly to the chest, or due to specific birth positions like squatting. Symptoms of damage to this nerve can include weakness and numbness in the leg and foot.
Diagnosis of common fibular nerve damage is typically based on a patient’s symptoms (like foot drop), as well as special tests like X-rays, MRIs, and electromyography. While X-rays and MRIs may not necessarily reveal the issue, they can help rule out other possible problems. The process of giving birth can, in some cases, indirectly cause foot drop, whether by prolonged squatting or by pressure on the leg applied by the patient herself or a healthcare worker. That’s why this condition is sometimes referred to as “pushing palsy.”
Risk Factors and Frequency for Foot Drop in Obstetrics
Obstetrical foot drop is a condition that affects women during their reproductive years. It’s quite rare, happening in just 0.92% of births.
There are certain risk factors associated with nerve injuries during childbirth:
- Having a prolonged labor, especially during the second stage, can increase the risk.
- Shorter women (5 feet or under) who are giving birth to a relatively large baby have a higher risk of injuries to their lumbosacral trunk. This is especially true if the baby is too big for the size of the pelvis.
- Also, having a bigger than average baby or if the baby is not in the correct position for birth, can up the risk of harm to the lumbosacral plexus.
- Risk factors for common fibular neuropathy include squatting during childbirth, bending the knee too far, or pressure applied by the hand of the person giving birth or the health professional assisting.
- Interestingly, one-sided cases of common fibular neuropathy can be linked to the dominant hand of the person giving birth.
Signs and Symptoms of Foot Drop in Obstetrics
During a routine physical examination, certain vital signs such as blood pressure, pulse rate, oxygen saturation, respiratory rate, and body measurements are taken into account. Among these assessments, doctors check for a particular condition known as foot drop, which signals weakness or nerve damage in certain muscles of the leg. These include the tibialis anterior – the most crucial for foot lifting, and the muscles responsible for toe extension.
The doctor can test the severity of muscle weakness by having the patient sit with their foot dangling off of an examination table. They will then push the patient’s foot downward while observing the resistance to that action. Comparison with the other foot can help see any differences.
The patient’s way of walking or gait is also monitored. If foot drop is present, the person may drag their toes, or lift their foot higher than usual to avoid tripping, mimicking the gait of a Tennessee walking horse. Another sign can be a loud footfall, where the patient’s foot loudly hits the ground due to limited control.
People with foot drop often find it challenging to walk on their heels because it requires active lifting of the foot. The doctor also checks for other losses in motor control. In a typical case of foot drop, these losses should be confined to the muscles that lift the foot.
They also examine any sensory loss or pain. They may perform Tinel’s sign, a test that involves tapping on the side of the leg to stimulate a specific nerve: the common fibular nerve. A positive response causes a tingling sensation that spreads from the tapping site.
The Lasegue straight-leg raising test can indicate a herniated disc, one potential cause of foot drop. An MRI scan can confirm this diagnosis. In addition, the Achilles tendon reflex should be normal, unless the patient has an issue with another nerve: the S1 nerve root.
Lastly, a neurological consultation may be necessary to determine exactly where the problem lies. It’s important to assure the patient that foot drop is not their fault and that this condition should respond well to treatment with compliance.
Testing for Foot Drop in Obstetrics
In diagnosing radicular pain due to a herniated lumbar disc, which is a condition where a disc in your lower spine bulges or breaks open, causing pain to travel along the nerve path, a test called the Lasegue Straight Leg Raising Test can be performed. During this test, you will lie flat on your back, and the doctor will raise your leg while it’s straight. If there’s a spinal irritation (possibly due to a herniated disc), you’ll feel pain along a specific area of your skin known as a dermatome, typically when your leg is lifted less than 60 degrees.
For certain affected discs (like L4/L5), the pain will typically travel down the side of your leg, across the top of your foot and include your big toe and second and third toes. For some other discs (like L5/S1), the pain will usually cover your heel and both sides of your fourth and fifth toes. Moreover, damage to specific nerve roots could cause loss of reflexes, like the Achilles tendon reflex.
To check how severe foot drop (a condition where difficulty lifting the front part of the foot results in dragging the foot along the ground when walking) is, while you’re seated at the edge of the examination table with your foot hanging off the edge, the doctor may use one hand to try and force your foot to bend at the ankle (a movement called plantar flexion). The doctor will then repeat on the other side to compare. The same test is used to assess specific nerves like the common fibular and deep fibular nerves since a lesion (damage or injury) on either of them could cause foot drop.
The doctor may also test for Femoral Neuropathy (a condition where damage to the femoral nerve causes pain, numbness, or weakness in the upper leg). For this, you’ll lie face down, and the doctor will hold your ankle and then lift your thigh. If this triggers pain and you have foot drop, it might suggest a condition where your nerves are affected (lumbosacral plexus lesion). You may also be asked to lie on your side and extend your leg against resistance to test the strength of your femoral nerve.
Tests for Obturator Internus Neuropathy (which would involve specific muscles responsible for rotating your leg inward) would include checking for weakness or pain as you’re asked to pull your thighs together against resistance. If foot drop is also present with this condition, it could indicate another type of nerve issue in the lower back referred to as lumbosacral plexopathy.
In diagnosing other lesions affecting nerves, an MRI of the lower spine can help determine if there is a herniated lumbar disc at a specific location (like L4/L5). If a herniated disc isn’t found, then other causes will be considered. Confirmatory tests, like an electrophysiological analysis which examines the electrical activity of your nerves, are also important for an accurate diagnosis.
Treatment Options for Foot Drop in Obstetrics
For a successful treatment of obstetrical neural injuries, such as nerve damage that happens during childbirth, an accurate diagnosis by a neurologist is key. This typically involves reviewing the patient’s medical history, conducting physical examinations and other special tests like imaging scans, which are especially vital for radiculopathies (a condition caused by a pinched nerve in the spine). Another integral part of the diagnosis is an electrophysiological examination to pinpoint the exact site of the lesion (damaged area).
In treating nerve injuries related to childbirth, it’s crucial to use non-surgical methods first, in case the issue was not caused by other underlying non-obstetrical conditions.
For a condition known as lumbosacral radiculopathy, patient education, exercise, manual therapy, and non-steroidal anti-inflammatory drugs are all employed part of the treatment plan. Oral corticosteroids, which are medicines to calm inflammation, may also be used during the acute (early) phase. If needed, pain relief injections with certain drugs might also be used. Methods like transcutaneous electrical nerve stimulation and lidocaine patches can be used to relieve pain. Neurosurgery can be considered only if other treatments are unsuccessful.
For lumbosacral plexopathy, a condition involving nerve damage in the lower back, treatment may include painkillers and muscle relaxants. Other medicines like amitriptyline, duloxetine, gabapentin, pregabalin, and opioids can be used. Physical therapy forms an essential part of the treatment for this condition.
A condition called Common Fibular Neuropathy, which is a nerve problem affecting the leg, can be treated with similar medications as lumbosacral plexopathy, along with physical therapy and gait retraining. Special supports called ankle foot orthoses can help patients walk better. In more severe cases, surgery might be considered to improve nerve function.
Typically, patients with a common fibular nerve injury regain full mobility within six months following the injury, with notable improvement often seen in the first two months. In some cases, symptoms may last for up to a year. However, total recovery is expected within two years, even if symptoms persist. Physical therapy plays a critical part in this process, focusing on certain exercises to stretch and strengthen affected muscles.
Regarding nerve damage that causes foot drop (difficulty lifting the front part of the foot), electrical stimulation can be used to prevent severe muscle atrophy (wasting away of muscles) and to promote muscle contraction if physical therapy alone is not enough.
What else can Foot Drop in Obstetrics be?
Foot drop can happen to a patient due to different types of injuries during childbirth. This condition can be triggered by damage to the roots of the lumbosacral plexus, often because of softened ligaments in the later stages of pregnancy. The lumbosacral plexus can also get injured directly, leading to foot drop. Another feature of this type of foot drop is that it can appear along with other nerve damage. Lesions of the lumbosacral trunk can also lead to foot drop, and they tend to occur due to compression from the baby’s head during birth.
Foot drop can also result if the common fibular nerve or its branch, the deep fibular nerve, gets injured. This typically happens when a patient’s legs are held flexed at the hip and knee during the pushing stage of labor, or when they are placed in a specific medical position known as the dorsal lithotomy position. Accordingly, a variety of different lesions can lead to foot drop, and diagnosing it involves identifying other symptoms and pin-pointing exactly where the damage occurred.
It’s important to consider motor losses, sensory losses, and pain while diagnosing foot drop. Tests such as an MRI may be helpful, especially in cases of L5 lumbar radiculopathy. When foot drop occurs due to L5 lumbar radiculopathy, there’s typically evidence of damage to the ligaments and nucleus pulposus at the L4/L5 level. Electrophysiological studies can provide detailed data about the damage and are more reliable than physical examinations, which depend on factors like the patient’s mental condition and ability to cooperate.
While diagnosing foot drop, it’s important to consider:
- Lumbar plexopathy, which can cause a sensory deficit or global muscle weakness in the lower extremity
- Radiculopathy, where pain or motor function loss follows a dermatomal or myotomal pattern respectively
- Foot Drop that involves the L5 nerve root, which can be traced as it’s present in the lumbosacral trunk and in the sciatic & common fibular nerves
- Common Fibular Neuropathy, which may manifest as weakness in foot movements and loss of sensation over certain areas of the lower limb
Tests such as electromyography and MRI of the lumbar spine are helpful in confirming the diagnosis and determining the extent of the damage.
What to expect with Foot Drop in Obstetrics
The outlook for patients experiencing foot drop due to pregnancy is generally positive if treated correctly. In cases where foot drop is caused by stress on the L5 nerve root (a nerve located in the lower back), symptoms typically disappear within six months after giving birth.
The results are also generally positive for those experiencing lumbosacral plexus plexopathy, a specific type of nerve damage, during or after childbirth. These symptoms typically go away within days to months. Only a small number of patients reported still having some symptoms at their last check-up, but these were usually minor and did not affect life quality.
After an injury to the common fibular nerve (a nerve in the leg), patients usually regain full mobility within six months, with significant improvements often seen within the first two months. In some cases, symptoms might persist for up to a year, but even in these prolonged cases, total recovery should still take place by the end of two years.
Possible Complications When Diagnosed with Foot Drop in Obstetrics
Recovery is generally straightforward if the patient follows the diagnosis and prescribed treatment plan.
The most significant risk is falling while the patient is trying to walk. Wearing supportive foot devices can help, but for serious conditions, using a walking aid may be necessary to ensure safe movement.
There’s a potential complication that the same problem might occur in a future pregnancy. This is particularly possible for short mothers with large babies, as the risk of such complications is usually higher during the first pregnancy. Though not a genetic condition, the physical factors causing foot drop could potentially be inherited.
It’s important that patients receive advice about maintaining a healthy diet – especially those who are overweight. Safely moving around with foot drop is already a significant challenge, and being overweight makes the situation even more difficult.
The patient should also be advised not to sit with their legs crossed. This position can make foot drop worse, particularly if the common fibular nerve becomes compressed. Chronic leg-crossing over several years could also lead to foot drop.
Important Guidelines:
- Patient adherence to diagnosis and treatment plan
- Use of supportive footwear or a walking aid for safe walking
- Understanding the potential genetic basis of foot drop in relation to future pregnancies
- Diet counselling particularly for overweight patients
- Avoid sitting with crossed legs to prevent nerve compression
Preventing Foot Drop in Obstetrics
When dealing with the risk of “obstetrical foot drop” (a condition that weakens the muscles responsible for lifting the front part of the foot), it’s crucial to be aware of the risk factors. If a pregnant woman is short, overweight, has gestational diabetes (diabetes that develops during pregnancy), and is expecting a large baby, it may be safer to have a cesarean section (or c-section, a surgical procedure to deliver the baby) instead of a vaginal delivery.
It’s important for patients to understand their condition and be reassured that if they follow the prescribed treatment, they’re likely to have a positive outcome. Providing psychological support can also be beneficial to help cope with the emotional distress that can accompany this unexpected issue during delivery.
If a patient wants to know more about what caused her foot drop, it can be discussed, but it’s also vital to reassure her that it’s not her fault. This condition is caused by the situation, not the person.
In terms of practical advice, a patient should never sit with her legs crossed, as this could potentially worsen her condition. If the patient is overweight, she may also benefit from dietary guidance. Lastly, it’s crucial that the patient is aware she may experience foot drop again during the delivery of a future pregnancy, if she chooses to have more children.