Some of the pregnancy-related physiologic changes such as fluid retention and weight gain may predispose to muscle cramps, carpal tunnel syndrome, and meralgia parasthetica. Compression of the lumbar and sacral plexi or their branches during labor and delivery may result in postpartum plexopathy and mononeuropathy. A variety of neuromuscular diseases including those caused by autoimmunity and genetic factors often occur in women of childbearing age who then become pregnant. Pregnancy may result in deterioration of the symptoms in some of the autoimmune diseases such as chronic inflammatory demyelinating polyneuropathy, myasthenia gravis, and myositis. The symptoms and/or the natural course of some genetic diseases such as inherited neuropathies, muscular dystrophies, and muscle channelopathies also may deteriorate during a pregnancy. Inherited neuropathies and myopathies also may result in abnormal outcome of pregnancy such as abnormal fetal presentation, or in increased rate of interventions such as forceps delivery and cesarean section. Patients with underlying respiratory muscle weakness and chest wall deformity should be considered high risk when pregnant. They should therefore be monitored closely by a multidisciplinary team of specialists, especially later in the pregnancy and during labor and delivery and early in the postpartum period.

Pathophysiology

Physiologic changes associated with pregnancy often result in musculoskeletal pathology (i.e., back pain and mononeuropathy) in a susceptible individual. The course and natural history of an underlying neuromuscular disease also may change as a result of hormonal or immunologic changes of a normal pregnancy. Below are some of the pregnancy-associated changes that are pertinent to certain kinds of neuromuscular diseases.

Fluid retention : Pregnancy results in a 30–50% increase in plasma and extracellular fluid volume. This is due to a primary renal sodium and water retention as well as a generalized vasodilation . Fluid retention may result in soft-tissue edema, thus predisposing to nerve entrapments, including carpal tunnel syndrome (CTS) and possibly Bell’s palsy (BP).

Weight gain : Physiologic weight gain during pregnancy is due to fluid retention, uterine enlargement, and the growing fetus. It results in a compensatory lumbar lordosis to adjust the center of the gravity . Weight gain and lordosis result in increased mechanical stress on the spine, thus contributing to the high prevalence of back pain in pregnant women. Weight gain is also a predisposing factor for meralgia paresthetica (MP).

Relaxin : Relaxin is a polypeptide hormone, and its elevation in pregnancy is thought to be involved in the ligamentous laxity of the sacroiliac, sacrococcygeal, and pubic joints . Elevated relaxin has been proposed in the pathogenesis of CTS by such mechanisms as fluid retention in the perineural connective tissue and relaxation of the flexor retinaculum . It has also been suggested that relaxin makes the intervertebral discs more vulnerable to stress, resulting in back and pelvic pain . However, the pathogenetic role of relaxin in the above-mentioned conditions remains controversial, as other studies have failed to demonstrate correlation of relaxin levels and joint laxity .

Compression of the pelvic floor neural structures : The enlarging uterus and the fetal head may compress the lumbar or sacral plexi, sciatic, obturator, and femoral nerves later in the pregnancy. Occasionally this results in plexopathy or mononeuropathy, especially at labor and delivery, when the compression of neural elements is more severe.

Labor and delivery : Forceps application may increase the risk of ischemic plexopathy and mononeuropathy due to prolonged compression of the pelvic floor neural elements. Prolonged lithotomy position, especially with excessive leg extension and external hip rotation is another risk factor for post-labor mononeuropathy. In a study of 991 patients who underwent a surgical procedure in the lithotomy position, 15 had unilateral or bilateral mononeuropathy . In that study, the obturator, lateral femoral cutaneous, sciatic, and peroneal nerves were involved in different patients. Furthermore, neuroaxial blockade (including epidural anesthesia), which is commonly used for labor or cesarean section, rarely results in lumbar radiculopathy or other neurologic deficits .

Altered immune responses : Autoimmune diseases commonly affect women of childbearing age. Activity of an autoimmune disease often changes as a result of pregnancy-related alterations of the immune responses. Improvement of some of the autoimmune diseases during pregnancy may be the result of increased tolerance to the autoantigens. Animal evidence suggests changes in the maternal T-cell immunoreactivity to accommodate the tolerance to the developing fetus . Furthermore, a human study found reduction of interleukin 2 (IL2) and increased soluble tumor necrosis factor (TNF) receptors in the third trimester of pregnancy, while the level of TNF-α and IL1 were unchanged . This suggests down-regulation of Th1 pathway responses during pregnancy. On the contrary, other lines of evidence suggest an increased susceptibility to autoimmunity in the pregnant women. Fetal-derived cells have been shown to circulate in the maternal blood during, and even long after the pregnancy (microchimerism) . Microchimerism is hypothesized to result in autoimmune disease in some cases, as the cells of fetal origin may be the target of an immune response, or they may act as immune effector cells against the mother’s autoantigens .

Altered respiratory function : Physiologic changes in the respiratory function during pregnancy may adversely affect the outcome of the gestation in a patient with an underlying respiratory muscle weakness. Although the total lung capacity is preserved or mildly decreased in a normal pregnancy, the functional residual capacity (FRC) decreases by 10–25%, starting at twelfth week of gestation . The reduction in FRC is due to 35–40% decrease in chest wall compliance . On the other hand, the efficiency of diaphragmatic function improves in the parturient due to the increased area of opposition of the diaphragm and the chest wall . Pregnancy does not significantly alter forced expiratory volume in second 1 (FEV1), or forced vital capacity (FVC), and abnormal FEV1, FVC, or their ratio should not be attributed to the pregnancy alone .

Neuromuscular Diseases that Result from Pregnancy, Labor, and the Postpartum Period

Carpal tunnel syndrome (CTS) : CTS is the most common pregnancy-related entrapment neuropathy. CTS results from the median nerve entrapment in the carpal tunnel, that is, the space between the flexor retinaculum and the distal radius and the carpal bones. Nocturnal hand dysesthesia that mainly involves the palmar surface of the first three fingers and improves with shaking of the hands is the most common presenting symptom. More severe stages are characterized by constant pain and numbness, and abnormal two-point discrimination in the median nerve distribution. Thenar atrophy and weakness of the thumb abduction, flexion, and opposition are seen in very severe cases. Other signs of CTS include Tinel’s sign: a radicular pain in the first three fingers with tapping on the median nerve at the wrist; and Phalen’s maneuver: paresthesia in the distribution of the median nerve with wrist flexion for 30–60 s.

Association of CTS and pregnancy, as well as the first case of transection of the carpal ligament during pregnancy, was first reported by Wallace and Cook in 1957 . In a longitudinal study by Melvin et al. , 31% of a cohort of 58 unselected pregnant women complained of symptoms suggestive for CTS, and 7% had diagnostic abnormalities in the nerve conduction study. All of the patients who were diagnosed with CTS in that study had at least one abnormal sensory nerve action potential, while abnormal motor nerve distal latency was present in only half of the patients with CTS. Bilateral CTS was noted in more than half of the affected subjects in that study. In a more recent, prospective study of 2364 pregnant women, only 2% were diagnosed with CTS . Symptoms were bilateral in about 70% and started in the third trimester in 85% of the women with CTS. Factors that are suggested to predispose to CTS in pregnancy include weight gain, primiparity, age of the mother, and presence of generalized edema .

Pregnancy-related CTS generally has a good prognosis and therefore is treated conservatively in most cases. Conservative treatment of CTS in nonpregnant patients includes wrist splints, nonsteroidal anti-inflammatory agents, low-salt diet, and hydrocortisone injections. Nonsteroidal anti-inflammatory agents should not be used late in pregnancy due to potential risk of premature constriction of the ductus arteriosus . In a longitudinal study by the Italian CTS study group on 37 untreated pregnant women with CTS, the symptoms resolved in 30% soon after delivery, 11% during lactation, and 5% after interruption of lactation . Interestingly, severe baseline symptoms were associated with a higher probability of later improvement, which could be due to greater behavior modification when the symptoms are more severe. In the study by Turgut et al. , 60% of the patients had resolution of the symptoms after delivery with the conservative treatment. Only 4% had symptoms 1 year postpartum and needed surgical decompression. In another study, conservative management of CTS with splinting of the wrist made 82% of pregnant women with CTS symptom free. Only 7% needed decompression surgery during or after the pregnancy .

Other upper extremity mononeuropathies : Pregnancy-related ulnar and radial neuropathies are rare compared to CTS. A patient with postpartum bilateral radial neuropathy was reported due to improper use of the birthing bars . Another patient had bilateral ulnar and radial neuropathy due to compression at the axilla, after the use of a birthing stool .

Intercostal neuralgia : Intercostal neuralgia usually manifests in the third trimester of pregnancy with radicular pain in the distribution of one or two thoracic nerve roots . It has been attributed to mechanical stretching from the enlarging uterus . A pregnant patient was reported to have intercostals neuralgia in right T8/9 distribution, which completely improved after delivery and recurred in a subsequent pregnancy . Herpes zoster infection, diabetic truncal polyradiculopathy, and structural lesions such as herniated thoracic discs are the main differential diagnosis. Amitryptiline and lidocaine patch (class B medication) and epidural anesthesia have been used to alleviate pain .

Bell’s palsy (BP) : The association of BP and pregnancy was first suggested by Charles Bell in 1830 . BP is characterized by paresis or complete paralysis of the facial nerve. Other associated symptoms may include pain, dry eyes, hyperacusis, impaired taste sensation in the anterior tongue, and reduced salivation. BP is usually unilateral, but bilateral and recurrent cases have been reported in pregnancy . Typically, BP presents with an acute onset over 1–2 days; progression may continue up to 1 week and may result in complete paralysis of facial innervated muscles.

A study by Hilsinger et al. , estimated the frequency of BP in pregnancy to be 45 per 100,000, which is higher than the general population (17 per 100,000). On the other hand, Vrabec, et al. have speculated that BP is not more common in the parturient than the general population . Pregnancy-associated BP is more likely to occur in the third trimester of pregnancy and the postpartum period . In the study by Hilsinger et al. , 74% of pregnancy-related BP occurred in the third trimester and another 12% in the first 2 weeks postpartum.

Fluid retention during the pregnancy may result in perineural edema and therefore, compression neuropathy of the facial nerve. In a retrospective study of 41 women with BP during pregnancy, 29.3% had pre-eclampsia or gestational hypertension, which is about 5 times the expected rate for the general population . Other potential pathogenesis includes reactivation of the herpes simplex virus in the geniculate ganglion, hypercoagulability, and hormonal changes .

The differential diagnosis of BP includes leptomeningitis (e.g., Lyme disease and neurosarcoidosis), myasthenia gravis, otitis media, cholesteatoma, malignant infiltration, herpes zoster oticus, and arteriovenous malformation . Diagnosis usually can be made solely on the clinical grounds in the typical cases. Atypical features include bilateral involvement, insidious or progressive course, severe ear pain, tinnitus, otorrhea, hearing loss, vestibular symptoms, or other cranial or peripheral nerve involvement. The presence of these atypical features should prompt a diagnostic workup, including a brain MRI, CSF examination, Lyme and myasthenia gravis serology, and nerve conduction study and electromyography.

One of the most important aspects of the treatment include prophylactic treatment of eye dryness with artificial tears during the daytime and a thicker ointment at night, eyelid taping or patching, or use of a moisture chamber . As treatment with steroids is suggested to improve the prognosis of BP in the general population, a course of oral prednisone (1 mg/kg for 5 days followed by a taper) has been recommended in complete BP beyond the first trimester of pregnancy . The fetal risks of steroids in later stages of pregnancy include adrenal suppression and low birth weight. The use of steroids is not recommended in the first trimester due to increased risk of cleft palate in the fetus . Another treatment option is nucleoside analogue antivirals such as valacyclovir and famciclovir. A study on BP in nonpregnant patients showed a better outcome with the combination of these antivirals and steroids compared to the steroids alone . The maximal efficacy of these medications is when they are started within 3 days of the onset of symptoms. Furthermore, the above mentioned antivirals are class B medications and unlikely to be teratogenic, making the risk to benefit ratio more favorable in pregnant women with BP. Facial nerve decompression has been performed in patients with severe axonal BP and has been suggested to improve the long-term prognosis . The prognosis of incomplete facial palsy is excellent, but a persistent deficit may be present in up to 50% of the patients with complete BP .

Backache and lumbar radiculopathy : More than 50% of pregnant women complain of back pain . It usually starts between the fifth and eighth months of the pregnancy, and radicular pain is reported in more than 40% of the patients . Pregnancy-related backache is often accompanied by a pelvic girdle pain which often radiates to the symphisis pubis or the posterior thigh. Ligamentous laxity of the pelvis and spine, lordotic posture, and weight of the uterus have been implicated as the predisposing factors .

In a study by Mantle et al. , the prevalence of severe back pain increased 5% for every 5 years of increase in maternal age; and there was no association with obesity, weight gain, and the weight of the fetus.

Despite the high prevalence of backache in pregnancy, herniated disc has only been reported in 1/10,000 of the parturient . Lumbar radiculopathy usually is unilateral, and affects the L5 or S1 nerve roots. Herniation of the nucleus pulposus commonly occurs posterolaterally, resulting in radicular pain that is often sudden in onset and exacerbated with coughing or straining. Segmental weakness or sensory or reflex changes may be present. A central disc herniation, on the other hand, may cause bilateral lumbar of sacral radiculopathy and sphincter dysfunction (cauda equine syndrome). Spinal and epidural anesthesia rarely result in a lumbar radiculopathy or other neurologic complications such as epidural hematoma when the tip of the needle touches the dural cuff and damages the nerve root or the artery that enters the intervertebral foramen .

Although backache and lumbar radiculopathy in pregnancy are often treated conservatively with bed rest and analgesics, surgical intervention should be considered in pregnant women with severe or progressive neurologic dysfunction or incapacitating pain due to lumbar radiculopathy . Patients with radicular pain and segmental weakness or numbness should undergo a timely workup, including electromyography and MRI study. MRI is the imaging method of choice in the parturient, as it does not expose the fetus to radiation, however, contrast injection should be avoided unless absolutely necessary .

Another less common cause of back pain in the postpartum period and even during the pregnancy is sacral fracture . In a retrospective study of 236 nonpregnant patients with sacral fractures secondary to trauma, Denis et al. showed that about 6% had neurological findings. The same study suggested that fractures that involve the sacral ala can result in L5 nerve root entrapment between the displaced fragment of the ala and the transverse process of L5 . More commonly, a radiculopathy does not occur with sacral fractures, and the symptoms are groin, buttock, and low back pain and tenderness on deep palpation of the sacrum, with a negative straight leg raising test . Sacral fracture in pregnancy may be secondary to an underlying metabolic bone disease such as a transient osteoporosis which is often associated with the pregnancy and lactation . It should be noted that plain X-ray has a low sensitivity for detecting a sacral fracture. Fracture line is seen better in a CT scan, while MRI study best shows the concomitant bone marrow edema .

Lumbar and sacral plexopathy : Plexopathy may result during a vaginal delivery from the compression of the plexi by the fetal head (specially the head of a macrosomic infant) or application of obstetric forceps (especially mid-forceps). Plexopathy is probably the most common cause of acute foot drop after the labor. In a study by Katirji et al. , six of seven patients with postdelivery foot drop had short stature and the other had a large newborn. Other predisposing factors for a plexopathy include a straight sacrum, a flat posterior pelvis, and prominent ischial spines .

Lumbar plexopathy presents with weakness of the hip adductors, hip flexors, and quadriceps. It should be differentiated from femoral neuropathy, which manifests with weakness of quadriceps with or without hip flexion; and obturator neuropathy (weakness of the hip adductors only). Psoas and retroperitoneal hematoma should be considered in patients with lumbar plexopathy. Although hematoma occurs more commonly in the setting of anticoagulation, it has also been reported after normal vaginal delivery .

Sacral plexopathy can be differentiated from sciatic neuropathy by the presence of weakness of the gluteus medius (hip abduction), gluteus maximus (hip extension), and anal sphincter in the former.

Labor-related lumbar and/or sacral plexopathy are usually treated conservatively as the neuropathic lesion is usually demyelinating, and complete recovery over a period of 5–6 months is expected . A less-favorable prognosis can be anticipated if severe axonal degeneration (i.e., absent or markedly abnormal compound muscle action potential (CMAP) amplitude) is detected in the nerve conduction study.

Meralgia paresthetica (MP) : MP is a mononeuropathy of the lateral femoral cutaneous nerve. Lateral femoral cutaneous nerve is a purely sensory branch derived from the lumbar plexus (L2–3). It is predisposed to compression and stretch injury at the level of anterior superior iliac spine, under or in the inguinal ligament . MP is characterized by dysesthesia, pain, and numbness in the anterolateral thigh without weakness or reflex changes. Symptoms often deteriorate with prolonged standing and improve with sitting. Often there is exacerbation of symptoms with tapping on the upper part of the inguinal ligament near the anterior superior iliac spine, and with hip extension, which stretches the nerve . The main differential diagnosis of MP is a lumbar radiculopathy. The presence of such findings as motor weakness, reflex changes, or a positive straight leg raise testing should prompt a diagnostic workup, including an MRI study of the lumbar spine . Otherwise, MP can be diagnosed based on the clinical presentation. MP can be spontaneous or iatrogenic. Spontaneous MP can be caused by stretching of the nerve in the setting of increased intra-abdominal pressure, such as pregnancy. Other predisposing factors for MP include weight gain, diabetes, and hypothyroidism . Spontaneous MP can occur at any time during the pregnancy or the postpartum period. It is usually unilateral, and bilateral involvement is seen in 8–12% of patients . Iatrogenic MP is caused by a number of orthopedic and pelvic operations, including cesarean section . Treatment of pregnancy-related MP is almost always conservative, such as minimizing periods of standing, and avoiding tight clothing. The patient should be reassured that the symptoms usually improve after delivery. More severe pain can be treated with local injection of methylprednisolone at the lateral border of the inguinal ligament.

Sciatic and peroneal neuropathy : The sciatic nerve is the largest branch of the sacral plexus and is derived from branches of L4–S3. It is deep to the gluteus maximus in its superior part, where it could be injured because of deep intramuscular injections. Other risk factors for a postpartum sciatic neuropathy include prolonged lithotomy position with knee extension and external hip rotation, and prolonged lateral tilt position during anesthesia . The prognosis of postpartum sciatic neuropathy is generally favorable .

The sciatic nerve divides to common peroneal and tibial nerve branches proximal to the knee joint. Peroneal neuropathy usually presents with unilateral or rarely bilateral postpartum foot drop and numbness and paresthesia in the lateral aspect of the leg and dorsum of the foot . A peroneal neuropathy can be differentiated from a sciatic neuropathy or L5 radiculopathy by the lack of weakness of the ankle inversion in the former. An electromyography (EMG) and nerve conduction study may help differentiating these potential causes of postpartum foot drop as well as predicting the prognosis. The peroneal nerve can be injured during labor by inappropriate leg positioning, hyperflexion of the knees, prolonged squatting, manual pressure on the knees during the labor, and prolonged second stage of labor . The postpartum peroneal neuropathy is usually predominantly demyelinating, and the prognosis is favorable.

Femoral neuropathy : The femoral nerve arises from the posterior divisions of L2–4 spinal roots and emerges from the psoas muscle. It then descends under the inguinal ligament to innervate the iliacus, sartorius, pectineous, and quadriceps femoris. It also provides sensation to the medial aspect of the thigh and leg through its terminal branch, the saphenous nerve. A femoral neuropathy should be distinguished from a lumbar radiculopathy or plexopathy (see lumbar and sacral plexopathy). Femoral neuropathy usually manifests by painless weakness of hip flexion, and severe weakness of the quadriceps. Thigh numbness or attenuated knee jerk also could be present. Femoral neuropathy rarely presents in the third trimester of pregnancy ; but the majority of pregnancy-related cases occur during the labor and delivery, with an estimated frequency of 1.5/1000 deliveries . Cephalopelvic disproportion, prolonged labor, primiparity, and prolonged lithotomy position are predisposing factors . As postpartum femoral neuropathy is usually demyelinating in nature, the treatment is conservative and the prognosis generally is good, and complete recovery is expected in the majority of patients within a 6-month period .

Obturator neuropathy : The obturator nerve is a branch of the lumbar plexus which arises from the anterior divisions of L2–4. Its anterior division innervates the pectineus, gracilis, and the adductor longus and brevis, as well as sensation to the medial aspect of mid and lower thigh. The posterior division provides innervation to adductor magnus and obturator externus. The obturator nerve is vulnerable to compression against the lateral wall of the pelvis as it crosses the upper margin of the obturator internus . In a retrospective study, only one of the 22 patients with obturator neuropathy was postpartum nature . Compression by the fetal head especially in the setting of cephalopelvic disproportion, forceps application, and prolonged lithotomy position are the predispoing factors . Obturator neuropathy often presents with neuropathic pain in the medial thigh which often radiates to the knee. Other symptoms include gait impairment due to hip adductor weakness . The treatment of obturator neuropathy is conservative and prognosis is generally good . A patient with severe neuropathic pain was successfully treated with obturator nerve block and steroid injection at the obturator foramen .

Pudendal neuropathy : The pudendal nerve arises from the sacral plexus (ventral divisions of S2–4) and innervates the perineal muscles, external urethral and anal sphincter, and skin of the perineum and labia major. Pudendal neuropathy may complicate a normal vaginal delivery due to compression by the fetal head, forceps application, or large episiotomies . It may result in pelvic floor weakness and urinary or fecal incontinence.

Muscle Cramps

A cramp is referred to a sudden, painful, involuntary muscle contraction which lasts for seconds to a few minutes. A cramp often begins and ends with fasciculations. Stretching of the affected muscles generally results in immediate resolution of a cramp. Pregnant women commonly experience cramps in the legs, which are more troublesome at night. Potential causes include pregnancy-related changes in fluid and electrolyte parameters or the compression of the pelvic neural structures by the enlarged uterus or fetal head. Such causes as hypothyroidism, uremia, and hyponatremia must be excluded. Regular exercise, multivitamin and mineral supplements, and magnesium lactate or citrate could be effective for the muscle cramps in the parturient .

Pregnancy and Underlying Neuromuscular Disease

Pregnancy may cause exacerbation or flare-up of a variety of autoimmune neuromuscular diseases because of changes in the immune responses. Furthermore, it is speculated that pregnancy could affect the natural history of some of the genetic neuromuscular diseases.

Furthermore, pregnancy-related physiologic changes of respiratory function (mentioned earlier) may have deleterious effects on the outcome of a pregnancy, and even prove to be life threatening to the parturient . Abnormal respiratory function in the neuromuscular diseases may be the result of respiratory muscle weakness and/or kyphoscoliosis . Managing a pregnant patient with respiratory muscle weakness may prove to be challenging and needs a multidisciplinary approach. Noninvasive positive pressure ventilation (NPPV) is often used and elective cesarean section is often considered to avoid the need for intubation and mechanical ventilation. Successful pregnancies have been reported with forced vital capacity of 50% and even much lower .

Inflammatory Neuropathies

Guillain–Barré syndrome (GBS) : GBS is an autoimmune, acute, monophasic polyradiculoneuropathy. Most of the cases in the United States and Europe are of the sensorimotor demyelinating type (acquired inflammatory demyelinating polyneuropathy; AIDP). Axonal subtypes, acute motor axonal neuropathy (AMAN), and acute motor and sensory axonal neuropathy occur in less than 10% of cases in the North America and Europe . AMAN is particularly common in China and another variant, Miller Fisher syndrome (MFS) is more prevalent in Japan . AIDP is characterized by progressive weakness, with maximal weakness present within 4 weeks, but usually within 2 weeks, after the onset . The weakness typically affects both proximal and distal limb muscles and frequently the truncal and respiratory muscles. Reflexes are typically absent early in the course. Facial neuropathy is seen in 70% of patients . Oculomotor involvement is less common, except in patients who are positive for GQ1b antibody, including those with MFS. Sensory symptoms are commonly present, including severe pain in some patients.

A history of a respiratory or gastrointestinal tract infection 3 weeks or less before the onset is present in about two-thirds of patients with AIDP . Molecular mimicry is the possible explanation for this association; that is, the immune response directed towards an infectious organism also is directed to the peripheral nerve antigens (e.g., gangliosides). Campylobacter jejuni is the most common pathogen in the nonpregnant population . AIDP associated with C. jejuni infection is also associated with seropositivity to IgG GM1, an axonal form, and less-favorable prognosis . Cytomegalovirus is the second most common infection associated with GBS . Cytomegalovirus infection and associated seropositivity to GM1 and GM2 antibodies has been associated with GBS in early and late pregnancy . Other more commonly encountered pathogens are Epstein–Barr virus, Mycoplasma pneumoniae , human immunodeficiency virus, and Haemophilus influenzae .

The incidence of GBS in pregnancy is estimated to be 0.75–2 in 100,000, similar to the general population . Although AIDP can present any time in a pregnancy, it is more common in the second and third trimesters, and in the first month of the postpartum period . There appears to be an increased frequency of GBS in the first 30 days postpartum compared to the general population . The occurrence of AIDP in the later stages of pregnancy often results in maternal respiratory failure and premature birth . However, the fetal survival rate was reported to be 96% in a review of 29 cases . Luijckx et al. reported a rare case of GBS in a newborn of a GBS patient with recent CMV infection.

Multidisciplinary care is needed to prevent potentially fatal complications. About 25% of patients with GBS who are unable to walk will need mechanical ventilation . Therefore, the vital capacity and respiratory rate must be closely monitored. Other important management issues include prophylaxis for deep vein thrombosis and appropriate treatment of fluctuations in the blood pressure, ileus, and urinary retention.

Plasma exchange (PE) and intravenous immunoglobulins (IVIG) are both proven to be effective in the treatment of GBS . PE and IVIG can safely be used in pregnancy . PE is more effective when it is given early in the course, and the usual regimen is a total exchange of 200–250 mL/Kg over a period of 10 days to 2 weeks . Hemodynamic changes (especially hypotension) often complicate PE. Other potential side effects of PE include septicemia, pneumonia, abnormal clotting, transfusion reactions including anaphylaxis and urticaria, and rarely transfusion-related infections .

IVIG has replaced PE as the preferred method of treatment in many hospitals, after a large randomized clinical trial showed its equal efficacy to PE . The usual dose is 2 g/kg over a 5-day period . A prospective study on 84 IVIG treatment courses in patients with neurologic diseases showed that the most common side effect was headache (30% of treatment courses). The treatment had to be stopped in 4% of the patients due to more severe side effects like thrombosis of the jugular vein, allergic reaction, and retrosternal pressure . Other common side effects of IVIG include nausea or vomiting, meningismus, exacerbation of chronic renal failure, hypercoagulability, and painful erythema at the infusion site .

The more severe cases of GBS who are bed-bound or require artificial ventilation have a worse prognosis than those who have less disability at the peak of their weakness . Other predictors of a poor outcome are rapid onset and axonal features (such as absent motor responses) in the nerve conduction study .

AIDP is not considered an indication for cesarean section or therapeutic abortion . The uterine contractions probably are not affected, however, cesarean section was performed in 61% of 23 patients with third-trimester AIDP . Both epidural and general anesthesia can be used. Caution should be exercised with the use of depolarizing neuromuscular blockers (e.g., succinylcholine) in patients with AIDP and other diseases that affect the lower motor neurons, because of potentially severe hyperkalemia . The proposed reason for this complication is proliferation of the postsynaptic acetylcholine receptors in diseases of the lower motor neurons. Depolarizing neuromuscular blockers may therefore result in increased release of potassium from the muscle in patients with these diseases .

Chronic inflammatory demyelinating polyneuropathy (CIDP) : CIDP is classically characterized by symmetrical weakness of the proximal and distal muscles of the upper and lower extremities. The disease progression should exceed 2 months, an important feature that differentiates CIDP from GBS (which is a monophasic, self-limited illness) . Other features of CIDP include sensory impairment, absent or attenuated deep tendon reflexes, demyelinating features in the nerve conduction study, elevation of CSF protein, and signs of demyelination in the nerve biopsy . Relapsing polyneuropathy was reported with pregnancy and oral contraceptive use even before the diagnostic criteria for CIDP were defined . In the patient reported by Calderon-Gonzalez et al., severe relapsing polyneuropathy occurred during the second or third trimesters of three subsequent pregnancies, with complete remission after the delivery each time. That patient probably had CIDP, as she had elevation of CSF protein level, very slow conduction velocities (<14 m/s), and segmental demyelination in a sural nerve biopsy . In a more recent study by McCombe et al. on nine women with CIDP who became pregnant, the onset of the neuropathy was during a pregnancy in 45%, and others had more relapses while pregnant. The symptoms generally worsened in the last trimester and the postpartum period in that study. Maintenance IVIG treatment has been shown to be effective for CIDP and should be considered in the parturient with this condition. Prednisone and intravenous methylprednisolone are category C medications, and can be used. Steroid-sparing agents such as mycophenolate mofetil, cyclosporine, and azathoiprine (all category D medications) must be used with extreme caution, if at all .

Multifocal motor neuropathy (MMN) : MMN is an autoimmune demyelinating neuropathy that is characterized by slowly progressive, asymmetrical weakness, and presence of conduction block in the motor nerves. Sensory nerves are typically not affected. Thirty to eighty-five percent of the patients with MMN are seropositive for IgM GM1 antibodies . An observational study showed deterioration of neuropathy and involvement of the unaffected nerves in three pregnant patients with MMN . The patients were treated with IVIG, and strength improved to the baseline level after delivery. As steroids may result in the exacerbation of weakness in the patients with MMN, it was suggested that increased disease activity could have been the result of endogenous corticosteroid secretion.

Hereditary Neuropathies

Hereditary motor and sensory neuropathies (Charcot–Marie–Tooth disease; CMT) are a genetically heterogenous group of progressive peripheral neuropathies that often affect the women in the childbearing age. CMT is caused by a number of mutations that affect the peripheral nerve myelination (CMT 1,4) or result in a primarily axonal degeneration (CMT2) . CMT is clinically characterized by pes cavus, symmetrical weakness and atrophy of muscles of the feet and legs, and to a lesser extent, weakness and atrophy of the hand muscles. The sensory symptoms are less prominent than the other neuropathies.

Association of CMT and pregnancy was first reported by Bellina and Deming , who reported a patient with increasing weakness and atrophy of the distal muscles in five subsequent pregnancies but no progression between the pregnancies. Pregnancy-related exacerbations were also noted in the patient’s sister. Pollock et al. , reported a previously asymptomatic patient with CMT who developed severe neuropathic pain in the third trimester of pregnancy, that resulted in an elective cesarean section. The patient improved 3 months after the delivery. The authors proposed increasing pressure of the enlarging uterus and the estrogen-induced endoneural edema as the potential causes of the observed deterioration.

In a retrospective study by Rudnik-Schoneborn et al. , childhood and juvenile onset but not the adult onset CMT, were predisposed to exacerbation of neuropathy symptoms. In that study, 38% of the patients reported exacerbation of weakness during at least one pregnancy, and in 65% of the patients who deteriorated, the deficits persisted after delivery. On the other hand, there was no adverse effect on the outcome of the pregnancy. In another study on 108 gestations of patients with CMT, the patients had a higher rate of fetal presentation abnormalities, including breech or abnormal cephalic presentations which resulted in increased rate of interventions like the use of forceps . That finding was hypothesized to be due to abnormal mobility of the fetuses, but involvement of the fetuses was not reported in that study.

Anesthetic management of the parturient with CMT depends on the severity of the disease. Patients with mild CMT may have a normal vaginal delivery with local or epidural anesthesia . On the other hand, if kyphoscoliosis and significantly impaired respiratory function are present, NPPV may have to be started in later stages of pregnancy and elective cesarean section should be considered . Depolarizing neuromuscular blockers should be avoided as there is a risk of severe hyperkalemia (see Guillain Barre Syndrome).

Autoimmune Inflammatory Myopathies

Dermatomyositis (DM) and polymyositis (PM) are the most common autoimmune inflammatory myopathies that affect women of childbearing age. Pregnancy is uncommon in DM/PM, as the two peaks of the onset are in the childhood and over the age of 45 . Flare-up of the underlying DM/PM often occurs in pregnancy or the postpartum period, although a fatal outcome for the mother has only rarely been reported . Four of the seven pregnant women with DM/PM had the onset, and three others had an exacerbation of their disease during pregnancy in a study by Gutierrez et al. . The outcome of the pregnancy in DM/PM depends on the disease activity, as well as the age of onset of the myositis. In a study on 28 women with DM/PM, 4 became pregnant, 2 of the 4 with an active disease had abortions, whereas the other 2 with an inactive disease had good fetal outcomes . In yet another retrospective study, only 42% of the pregnancies in DM/PM resulted in normal deliveries, with a strong correlation between the outcome of the pregnancy and the activity of the myositis . The risk of getting pregnant should be discussed with the patients of childbearing age, and pregnancies are better planned when the disease is in remission . Muscle strength, respiratory muscle function, and serum CPK should be closely followed during the pregnancy, and flare-ups of the myositis should be treated aggressively . Prednisone (starting at 1 mg/kg) is a category C medication and usually is the first line of treatment for DM and PM during pregnancy. IVIG should also be considered a second line of treatment . Some authors have suggested that because DM and PM could have a very aggressive course during pregnancy, such steroid-sparing agents as azathioprine and cyclosporive have to be considered in the more severe cases . DM/PM generally do not affect the uterine contractility, but forceps or vacuum extraction has to be considered if there is generalized muscle weakness .

Hereditary Myopathies