Abstract
The choice of anesthetic technique for pregnant women with neurologic disease requires knowledge of the pathophysiology of the disorder and an understanding of controversies involved in the diagnosis and management of the disease. If a patient’s neurologic condition deteriorates postpartum, the cause may be unclear and the anesthetic technique may be blamed unfairly. There are limited published data on specific neurologic and neuromuscular disorders in pregnant women. However, few of these disorders contraindicate the use of neuraxial anesthesia. In most cases, the obstetrician should obtain early antepartum consultation from an anesthesia provider. Early consultation allows accurate antepartum documentation of the extent and pattern of the neurologic deficit as well as discussion and formulation of the anesthetic plan with the patient, her obstetrician, and a neurologist or neurosurgeon.
Because patients with a wide variety of neurologic disorders will present for preoperative evaluation, a systematic work-up and thought process that includes an assessment of risks and benefits will assist the clinician with completing a proper evaluation and formulating an anesthetic plan.
Keywords
Neurologic, Neuromuscular, Management, Treatment, Obstetric, Anesthesia
Chapter Outline
Multiple Sclerosis, 1161
Headache during Pregnancy, 1163
Spinal Cord Injury, 1165
Myasthenia Gravis, 1168
Epilepsy, 1170
Myotonia and Myotonic Dystrophy, 1172
Muscular Dystrophy, 1174
The Phakomatoses (Neurocutaneous Syndromes), 1174
Neurofibromatosis, 1174
Tuberous Sclerosis, 1175
Cutaneous Angiomatosis with Central Nervous System Abnormalities, 1176
Acute Idiopathic Polyneuritis (Guillain-Barré Syndrome), 1176
Poliomyelitis, 1176
Brain Neoplasms, 1177
Idiopathic Intracranial Hypertension, 1180
Maternal Hydrocephalus with Shunt, 1180
Intracerebral Hemorrhage, 1180
Cerebral Vein Thrombosis, 1182
Obstetric and Anesthetic Management, 1182
Motor Neuron Disorders, 1182
Isolated Mononeuropathies during Pregnancy, 1183
The choice of anesthetic technique for pregnant women with neurologic disease requires knowledge of the pathophysiology of the disorder and an understanding of controversies involved in the diagnosis and management of the disease. If a patient’s neurologic condition deteriorates postpartum, the cause may be unclear and the anesthetic technique may be blamed unfairly. There are limited published data on specific neurologic and neuromuscular disorders in pregnant women. However, few of these disorders contraindicate the use of neuraxial anesthesia. In most cases, the obstetrician should obtain early antepartum consultation from an anesthesia provider. Early consultation allows accurate antepartum documentation of the extent and pattern of the neurologic deficit as well as discussion and formulation of the anesthetic plan with the patient, her obstetrician, and a neurologist or neurosurgeon.
Because patients with a wide variety of neurologic disorders will present for preoperative evaluation, the following thought process will assist the clinician with completing a proper evaluation and formulating an anesthetic plan.
What is the basic pathophysiology of the neurologic disorder? Neurologic disorders may be stable, progressive, or relapsing/recurrent. It is important to understand the common disease patterns. The potential for progression of the disease after delivery will depend on the pattern of progression and underlying pathophysiology, and on the effect of pregnancy on disease progression.
What is the patient’s history and current findings after neurologic examination? A history should include the onset date and current course of the disorder. Symptoms related to neurologic issues should be documented (e.g., seizure type and frequency, deficits after cerebrovascular events, cognitive deficits). A basic physical examination should be conducted to document existing deficit patterns, including cognitive dysfunction (e.g., ability to understand and cooperate), deficits involving vision, hearing, speech, and swallowing; respiratory symptoms; and weakness and sensory deficits in the head and neck, trunk, and extremities. Motor and sensory deficits are classified as mild, moderate, or severe, with a description of the affected area. Special attention should be directed to limitations in ambulatory ability (e.g., bed-bound, wheelchair, walking with assistance) or positioning.
What are the current treatments, and what testing results are available? Documentation of medical and nonmedical therapies is essential. For some disorders (e.g., myasthenia gravis), documentation of the timing of treatment is also critical. In most cases, specific laboratory testing will not influence anesthetic management and outcome. However, pulmonary function testing should be considered in patients with neurologic disorders that result in significant respiratory compromise; the findings may assist the anesthesia provider in making recommendations about anesthetic management.
What is the impact of the neurologic disorder on other organ systems (e.g., cardiac, respiratory, airway)? The patient’s neurologic disease may affect organ systems that are relevant to the anesthetic plan. For example, central core disease is associated with a risk for malignant hyperthermia. In addition, progressive neurologic disorders may significantly compromise the patient’s respiratory status, thereby increasing the risks associated with neuraxial and general anesthesia.
What are the potential impacts, risks, and benefits of anesthetic options based on the disease’s pathophysiology, symptoms, and treatment? Can treatment be initiated antepartum or before delivery that will improve outcome? For most rare neurologic disorders, there is limited evidence on which to base decisions about anesthetic management. In these cases, the anesthesia provider should consider the disease’s basic pathophysiology and its possible direct and indirect interactions with specific anesthetic techniques. Encouraging the obstetrician to send these patients for early antepartum consultation will enable the anesthesia provider to obtain formal input from a neurologist or other consultant if necessary. A multidisciplinary discussion that includes the patient and her family may be necessary to weigh the risks and benefits of specific obstetric and anesthesia plans. A team approach to peripartum care in patients with complex neurologic disorders is essential.
What are the plans for postpartum management of the patient’s disease? Will the intrapartum anesthetic management or postpartum analgesia management influence outcomes? Some conditions, such as multiple sclerosis, can have significant implications for the postpartum period. The anticipated progress of the disease and planned postpartum management should be discussed with the patient in the antenatal period.
In all cases, accurate documentation of the responses to the previous questions will greatly assist the team providing peripartum care for these patients. Some of the more common neurologic conditions are addressed in this chapter, and the existing literature is surveyed relative to the peripartum management of these patients. This knowledge allows the anesthesia provider an opportunity to formulate a safe and rational anesthetic plan as well as enable an appropriate discussion with the patient regarding the risks and benefits of anesthetic options.
Multiple Sclerosis
Multiple sclerosis is a major cause of neurologic disability in young adults, and it is at least two to three times more common in females than in males. First-time symptoms typically manifest in the second or third decade of life; therefore, the disease typically presents in females in their reproductive years. The prevalence of the disorder varies with the population, and may be as high as 300 per 100,000 in some parts of North America, although the accuracy of epidemiologic estimates have been limited by heterogeneous methods for identifying people with disease and by different data analytic strategies.
The disease is characterized by variable neurologic disabilities with two general patterns of presentation: (1) exacerbating remitting, which accounts for 85% of cases, in which attacks appear abruptly and resolve over several months; and (2) chronic progressive, in which continued deterioration occurs over time. The relapse rate varies significantly among patients, averaging approximately 0.4 attacks per year; this rate reflects the large proportion of patients with relapsing/remitting disease. The deficits tend to become more progressive and debilitating over time. Environmental factors (e.g., stress, infection, increased body temperature) may provoke a relapse. Most relapses reproduce previously experienced neurologic deficits, which can manifest as pyramidal, cerebellar, or brainstem symptoms. It is estimated that about one-half of affected individuals with exacerbating remitting disease will eventually convert to chronic progressive.
The etiology remains unclear, although it is widely believed to be autoimmune in nature. There is a clinically significant heritable component, and alleles in the HLA locus have been identified as risk factors for multiple sclerosis. Pathologic findings include local inflammation, demyelination, gliotic scarring, and axonal loss; on magnetic resonance imaging (MRI), the formation of gray and white matter plaques is seen. It is possible that the disease results from a yet undetermined combination of genetic predisposition and exposure to specific environmental factors. The more common symptoms include motor weakness, impaired vision, ataxia, bladder and bowel dysfunction, and emotional lability.
Although there is no cure, over the last two decades relapsing/remitting multiple sclerosis has become a treatable disease as a result of advancements in disease-modifying therapies. Immunosuppressive therapies may hasten recovery from a relapse, but no evidence suggests that these agents influence the progressive course of the disease. Administration of interferon-beta may significantly reduce the relapse rate and retard disability; however, an increased risk for fetal loss and low birth weight (LBW) has been observed with the use of this therapy during the first trimester of pregnancy. In contrast, administration of intravenous immunoglobulin or plasmapheresis for severe relapses has no known adverse effects on pregnancy outcome. Acute relapses during pregnancy are treated with short courses of high-dose corticosteroids, although longer-term use may be associated with maternal glucose intolerance, neonatal adrenal suppression, cleft palate if used in the first trimester, and an increased risk for premature rupture of membranes.
Interaction with Pregnancy
The effects of multiple sclerosis and long-term use of disease-modifying therapies on fertility are poorly studied. Findings from a prospective study in Finland suggest that multiple sclerosis is associated with increased requirement for assisted reproductive techniques. A large Danish national cohort study found that multiple sclerosis was associated with having no or fewer children ; however, it is not known whether this finding is explained by the disease itself or if it is caused by altered reproductive behaviors among diseased individuals. In one study of women with multiple sclerosis undergoing assisted reproductive techniques, failed assisted reproductive attempts were associated with increased annual relapse rates. These findings may be explained by the stress of infertility, temporary interruption in disease-modifying therapy, and increases in inflammatory cytokines associated with hormonal therapies.
Pregnancy and obstetric outcomes in women with multiple sclerosis are likely no different from individuals without disease. One cohort study compared 198 affected women with 1584 healthy women; the number of maternal complications was not higher in women with multiple sclerosis. However, infants delivered of women with multiple sclerosis were at greater risk for meconium aspiration. This finding may reflect an intrauterine environment in patients with multiple sclerosis that is more susceptible to acute hypoxic events. A subsequent cohort study of 649 pregnancies in women with multiple sclerosis concluded that infants of these women were more likely to be small for gestational age, attributed to a suboptimal intrauterine environment. Moreover, this study found that mothers with multiple sclerosis were more likely to undergo induction of labor and operative delivery, possibly as a result of neuromuscular weakness and spasticity. These findings have not been reproduced in other studies. A 2017 United Kingdom case-controlled study of 181 pregnancies in 98 mothers with multiple sclerosis and 244,573 pregnancies in 124,830 mothers without multiple sclerosis did not find any associations with neonatal birth weight, gestational age at birth, mode of delivery, stillbirth, or neonatal death. A 2011 meta-analysis did not find significant associations between multiple sclerosis and adverse obstetric and neonatal outcomes. The relapse rate was lower during pregnancy than before or after pregnancy.
Data from prospective studies suggest that the rate of relapse increases during the first 3 months postpartum in comparison with the year before pregnancy. Relapses during this period were more likely in women who had higher relapse rates in the year before pregnancy or during pregnancy. Stress, exhaustion, infection, the loss of antenatal immunosuppression, and the postpartum decline in concentrations of reproductive hormones may account for the higher postpartum relapse rate. Treatment with immunologically active agents (e.g., interferon-beta) may result in a decreased postpartum relapse rate, but data are limited.
Pregnancy does not negatively affect the long-term outcome of multiple sclerosis. Rather, at least one study has suggested that parturition may have a slightly favorable effect on long-term disease activity. Data are conflicting as to whether exclusive breast-feeding is associated with a lower risk for relapse than partial or no breast-feeding. A 2015 prospective study in 201 German women found a modestly protective effect against relapses among women with multiple sclerosis who exclusively breast-fed for at least 2 months (first postpartum relapse adjusted hazard ratio, 1.70; 95% confidence interval [CI], 1.02 to 2.85; P = .04).
Anesthetic Management
The anesthesia provider should assess the patient’s level of compromise, document the pattern of deficits, and give special attention to respiratory involvement, in particular the ability to cough, clear secretions, and take vital capacity breaths. Historically, the optimal mode of anesthesia in patients with multiple sclerosis has been controversial. Most anesthesia providers have considered general anesthesia to be safe. Many anesthesia providers have been reluctant to administer neuraxial anesthesia because the effect of local anesthetic drugs on the course of the disease is unclear. Some anesthesia providers have expressed concern that neuraxial anesthesia may expose demyelinated areas of the spinal cord to potentially neurotoxic effects of local anesthetic agents. Several animal studies have investigated the histologic effects of local anesthetic agents on the normal spinal cord. In one study, subarachnoid injection of small doses of a local anesthetic agent produced no histologic changes in the spinal cord or meninges. Injection of very large doses caused reversible inflammatory and degenerative changes, but all changes resolved within 14 days of injection.
Diagnostic lumbar puncture is not associated with a higher rate of relapse. Two small reports have implicated spinal anesthesia in the exacerbation of multiple sclerosis. Bamford et al. described one case of relapse after the administration of spinal anesthesia in 9 patients, and Stenuit and Marchand identified two cases of relapse after the administration of spinal anesthesia in 19 patients. The relationship of these relapses to spinal anesthesia or other postoperative conditions (e.g., stress, infection, hyperpyrexia) known to exacerbate multiple sclerosis is unclear.
There are few published data on the use of epidural anesthesia in patients with multiple sclerosis. Warren et al. reported minor exacerbations after the administration of epidural anesthesia for two separate vaginal deliveries in one patient. Crawford et al. reported one postoperative relapse in 50 nonobstetric and 7 obstetric patients who received epidural analgesia. Confavreux et al. reported a study of 269 pregnancies in 254 women with multiple sclerosis, of whom 42 received epidural analgesia; epidural analgesia did not have an adverse effect on the rate of relapse or on the progression of disability in these patients. Bader et al. retrospectively evaluated 32 pregnancies in women with multiple sclerosis; they observed that women who received epidural anesthesia for vaginal delivery did not have a higher incidence of relapse than those who received only local infiltration anesthesia. The Pregnancy in Multiple Sclerosis (PRIMS) study followed 227 women who had multiple sclerosis for at least 1 year before conception, of whom 42 received epidural analgesia during labor; no adverse effect of epidural analgesia on the rate of postpartum relapse or the progression of disability was identified. Similarly, a 2012 prospective study followed 349 patients for 5 years postpartum and did not find an increased risk for relapse associated with labor epidural analgesia. A 2013 record linkage study comparing 431 deliveries in women with multiple sclerosis who received peripartum neuraxial analgesia or anesthesia to 2959 deliveries in women from the general population in British Columbia did not find an association between the use of neuraxial techniques and increased disability.
Bader et al. observed that all of the women who experienced a relapse after epidural anesthesia had received a concentration of bupivacaine greater than 0.25%. The concentration of local anesthetic in the CSF progressively increases during prolonged administration of epidural anesthesia, and the authors suggested that the higher concentration may overwhelm the protective effect of dilution within the CSF. An alternative explanation is that women who require a higher concentration of neuraxial local anesthetic may have more stressful labor. However, these observations suggest that anesthesia providers should use a dilute solution of local anesthetic for epidural analgesia during labor, when possible.
The administration of neuraxial anesthesia for cesarean delivery is considered safe. Because the operation is of limited duration, multiple doses of local anesthetic are typically not needed, so a progressive increase in CSF concentration of local anesthetic over time is less likely. The 2013 record linkage study from British Columbia compared spinal anesthesia use in cesarean deliveries in 128 women with multiple sclerosis and 846 women in the general population, and did not find a link between spinal anesthesia and increased disability. Although there are limited data on spinal and general anesthesia for cesarean delivery in patients with multiple sclerosis, they are both considered safe, and prior concerns over these techniques are attributable to recall bias associated with postpartum relapses after regional anesthesia. No data suggest harmful effects of neuraxial opioids in women with multiple sclerosis. In light of the significant benefits of neuraxial techniques for intraoperative anesthesia and postoperative analgesia, either spinal or epidural anesthesia is the principal anesthetic technique used for cesarean delivery in patients with multiple sclerosis in many institutions, including our own.
In summary, published data do not contraindicate the use of neuraxial anesthetic techniques for labor analgesia or operative anesthesia. The patient should be aware that there is a higher incidence of relapse during the postpartum period, even without the use of neuraxial analgesia or anesthesia. In addition, when anesthetic techniques are used, the type of anesthesia selected does not appear to influence the relapse rate. Neither pregnancy nor anesthesia appear to have a negative influence on the long-term course of the disease. The willingness of anesthesia providers to use neuraxial techniques in pregnant patients with multiple sclerosis is reflected in a survey of obstetric anesthesia providers published in 2006. The majority (91%) of respondents had seen fewer than 10 cases of multiple sclerosis in the past 10 years; 79% and 98% of anesthesia providers indicated they would perform a neuraxial anesthetic technique for labor and elective cesarean delivery, respectively.
Headache During Pregnancy
Headaches are among the most frequently observed neurologic symptoms during pregnancy ( Table 48.1 ). Tension headaches, migraine headaches, and headaches associated with hypertensive disorders of pregnancy are commonly observed during pregnancy. De novo primary headaches (e.g., tension and migraine) are very common during pregnancy, particularly in the first few months of pregnancy; however, new headaches in the third trimester and puerperium should prompt closer evaluation for secondary causes. A pregnant patient with a history of chronic headaches who reports new or different symptoms should be closely evaluated to exclude serious causes such as preeclampsia, tumor, or intracranial vascular malformation. Symptoms of concern include sudden onset, intense severity, altered mental status, meningeal signs, fever, vomiting, changes in vision, pulsatile tinnitus, headache in a woman with prior malignancy or HIV infection, and any localizing or lateralizing abnormality. All imaging modalities may be used to assist in the diagnosis of secondary headaches in pregnancy, although measures should be taken to minimize maternal and fetal exposure to ionizing radiation.
| Etiology | Symptoms | Pattern | Treatment |
|---|---|---|---|
| Tension headache | Dull, widespread headache | Increased incidence during peripartum period | Analgesics Tricyclic antidepressants |
| Migraine headache | Frontotemporal throbbing Prodrome of scotomata | Improvement in 79% of patients during pregnancy | Ergotamine contraindicated during pregnancy Promethazine Beta-adrenergic receptor antagonist for prophylaxis |
| Preeclampsia | Generalized headache Occasional scotomata and/or blurred vision | Occurrence during pregnancy and occasionally postpartum | Blood pressure control Delivery |
| Meningeal irritation (subarachnoid hemorrhage, meningitis) | Generalized headache | Increased risk for subarachnoid hemorrhage during pregnancy | Based on etiology |
| Brain tumor | Variable | No increase in incidence during pregnancy; possible increased growth rate | Based on etiology |
| Idiopathic intracranial hypertension | Generalized headache Visual symptoms | Increased incidence and worsened symptoms during pregnancy | Typically remits within 1 to 3 months or after childbirth |
Tension Headache
Tension or muscle contraction headaches are the most common type of headache observed during pregnancy. The symptoms typically consist of dull, persistent pain that extends over the entire head. The onset is usually gradual, but the symptoms may persist for long periods. Although the etiology is unknown, this type of headache is believed to be associated with stress rather than hormonal changes. These headaches are more common in women, are frequently associated with anxiety, and may be a symptom of postpartum depression.
Treatment
Acetaminophen should be used as a first-line analgesic in the pregnant patient. Caffeine and butalbital may be contained in combination analgesic products (e.g., Fioricet, Fiorinal). The American College of Obstetricians and Gynecologists (ACOG) has concluded that there is no clear evidence that caffeine exposure increases the risk for fetal growth restriction. Because a definitive conclusion regarding high caffeine intake and the risk for miscarriage cannot be made, the ACOG recommends caffeine be limited to moderate consumption (less than 200 mg/day) during pregnancy. Butalbital is sometimes prescribed for treatment of migraine and tension headaches, but its appropriateness has been questioned given increased risks for abuse, overuse headache, and withdrawal. Emerging data from the National Birth Defects Prevention Study, an ongoing case-control study, suggest that butalbital exposure in pregnancy is associated with an increased risk for congenital heart abnormalities, including tetralogy of Fallot, pulmonic stenosis, and atrial septal defect. Butalbital use, however, was rare; only 73 case mothers and 15 control mothers reported periconceptional use.
Ergot alkaloids (e.g., ergotamine) are contraindicated during pregnancy; these agents may cause marked increases in uterine tone, which may compromise placental perfusion and fetal oxygenation. Use of nonsteroidal antiinflammatory drugs (NSAIDs) should be limited during the third trimester because of risk for premature closure of the fetal ductus arteriosus, oligohydramnios, and prolongation of pregnancy. Although a 2013 review did not find evidence that first-trimester exposure to benzodiazepines is associated with an increased risk for congenital malformations, these drugs are not usually used to treat headache during pregnancy. Opioids have a long record of safe use during pregnancy, but because of escalated use and abuse, and their association with neonatal opioid withdrawal syndrome with long-term maternal exposure, their prescription during pregnancy and the puerperium is undergoing increased scrutiny. Tricyclic antidepressants similarly have a record of safe use during pregnancy. Although earlier studies reported links between tricyclic antidepressant use during pregnancy and congenital malformations, most subsequent larger studies have been negative. Findings from one study suggest that tricyclic antidepressants do not have detrimental effects on the neurodevelopment of children exposed in utero .
Obstetric and Anesthetic Management
Pregnancy is not likely to reduce the frequency or severity of tension headaches because they are not hormonally mediated. Obstetric and anesthetic management are rarely affected by the presence of tension headaches, although a history of chronic tension headaches has been associated with an increased risk for placental abruption (adjusted odds ratio [OR], 1.60). The frequency and severity of tension headaches should be assessed and documented in the preanesthetic assessment to better differentiate preexisting symptoms from new or changing symptoms in the postpartum period.
Migraine Headache
Migraine headaches are classically described as unilateral, throbbing headaches sometimes accompanied by nausea and vomiting. The duration varies from hours to days. Visual disturbances (e.g., scotomata) typically precede the onset of these headaches, and focal neurologic symptoms (e.g., aphasia, hemiplegia) may also occur. Most investigators favor neurovascular vasospasm, followed by cerebral vasodilation, as a cause of these headaches; a primary vascular disorder or a disturbance in the noradrenergic nervous system also may be involved. Patients appear to be more susceptible to symptoms when serotonin levels are low.
The 1-year period prevalence of migraine headache in the United States is 3.9% for men and 5.1% for women. Prevalence is higher in middle life, between 30 and 59 years of age. Hormonal influences have a strong association with these headaches; estrogen withdrawal is associated with an exacerbation of symptoms. After delivery, the reduction in hormonal concentrations coincides with an increase in migraine symptoms.
Treatment
In nonpregnant patients, therapy centers around prevention, abortive treatments, and rescue treatments. Preventive medications are typically avoided during pregnancy; beta-adrenergic receptor antagonists (e.g., propranolol) may be used for prophylaxis, however, owing to their ability to cross the placenta, these agents should be used only when a patient’s symptoms are severe. Antidepressants such as selective serotonin reuptake inhibitors can be used off-label for migraine prevention, although fetal exposure to some antidepressants has been controversially linked to congenital anomalies and adverse neonatal outcomes (see Chapter 50 ). Abortive treatments often involve triptans or ergotamine tartrate, typically in combination with caffeine (e.g., Cafergot, Migergot). However, ergot alkaloids are contraindicated during pregnancy because of associated uterotonic effects and possible (but unproven) teratogenic effects. The use of sumatriptan or other selective serotonin receptor agonists is controversial. A higher incidence of congenital anomalies was observed after administration of high doses of sumatriptan in animals ; however, in a review of human studies, no evidence of any specific adverse effect of sumatriptan on pregnancy outcome was found. A prospective study also showed no relationship between triptan use for migraine and teratogenicity.
Rescue treatments are given when abortive therapies fail and include acetaminophen, antiemetics, and NSAIDs. In general, acetaminophen is considered the first-line treatment during pregnancy. Combination therapy with agents containing caffeine and/or butalbital should be used with caution, as should therapy with NSAIDs (see earlier discussion). Occasionally, calcium entry–blocking agents are used.
Obstetric and Anesthetic Management
Women with a lifetime history of migraine have been reported to have a twofold higher risk for placental abruption. Pregnant women with migraines are at four times higher risk for developing preeclampsia, as well as at higher risk for stroke during pregnancy and the puerperium.
Cerebral ischemia has been reported after the administration of terbutaline in pregnant patients with migraine. Rosene et al. recommended that physicians avoid the administration of terbutaline in pregnant women with a history of vascular headache.
Although there are no published data on the relationship between intrapartum anesthesia and postpartum migraine headaches, one cohort study suggested that patients with a prior history of migraine may be more likely to present with atypical symptoms of post–dural-puncture headache, including nonpostural headache; cervical, thoracic, or lumbar vertebral stiffness and pain; and vertigo.
Spinal Cord Injury
Worldwide, there are large geographic differences in the incidence, prevalence, and lethality of spinal cord injuries. In the United States, traumatic spinal cord injuries occur with an incidence of 23.7 to 77.0 per million population per year; the prevalence per million inhabitants is 473 to 1800. Improved handling and stabilization of victims at the site of an accident and the availability of extensive rehabilitation services have resulted in more women who present for obstetric care after spinal cord injury than in the past.
Patient disability and residual function depend on the anatomic location of the injury. Cord injuries below S2 involve mainly bladder, bowel, and sexual functions. Affected patients have relaxed perineal muscles, and women with such injuries experience labor pain. Women with a lesion above T10 do not experience labor pain. Patients with a lesion above T6 have varying levels of respiratory compromise and are at risk for autonomic hyperreflexia (see later discussion).
Spinal shock, defined as immediate and temporary areflexia/hyporeflexia and transient sensorimotor dysfunction resolving within 24 to 48 hours after injury, may develop in about one-half of spinal cord–injured patients. Patients with injuries at or above the T6 level are at risk for neurogenic shock caused by loss of signals from the sympathetic nervous system. It is characterized by hemodynamic and sensorimotor abnormalities, and flaccid paralysis with loss of tendon and autonomic reflexes. Patients experience loss of vasomotor tone, temperature regulation, sweating, and piloerection in the parts of the body below the lesion. Pulmonary edema, hemodynamic instability, and circulatory collapse can develop in the absence of brainstem regulation of vasomotor tone. Patients are at risk for aspiration, infection, and other pulmonary complications. Paraplegic patients may have a compensatory tachycardia, whereas quadriplegic patients may have bradycardia caused by unopposed vagal tone.
After a variable period, the spinal cord-injured patient progresses to a chronic stage in which reflex activity is regained. In most cases, this return of reflex activity occurs within 1 to 6 weeks after the injury; rarely, return of reflex activity may take several months. This stage is characterized by disuse atrophy, flexor spasms, and an exaggeration of reflexes. The mass reflex is a phenomenon in which a stimulus that normally would cause the contraction of a few muscle units leads to the widespread spasm of entire muscle groups. It results from the absence of central inhibitory mechanisms. The mass reflex can occur with any level of spinal cord injury. It may occur with autonomic hyperreflexia in a patient with a lesion above T6.
Approximately 85% of patients with chronic spinal cord injuries at or above T6 experience the syndrome of autonomic hyperreflexia. This is a life-threatening complication that results from the absence of central inhibition on the sympathetic neurons in the cord below the injury. Noxious stimuli, including bladder or bowel distention and uterine contractions, result in afferent transmission by means of the dorsal spinal root ( Fig. 48.1 ). These afferent neurons synapse with sympathetic neurons, and the impulse is propagated both cephalad and caudad in the sympathetic chain, without central inhibition. The propagation results in extreme sympathetic hyperactivity and severe systemic hypertension secondary to vasoconstriction below the level of the lesion. In response, the reflex arcs involving the baroreceptors of the aortic and carotid bodies lead to bradycardia and vasodilation above the level of the lesion. In patients with lesions at T6 and above, these compensatory mechanisms are insufficient to compensate for the severe hypertension. Intracranial hemorrhage, arrhythmias, and myocardial infarction occur in some cases. A variety of agents have been used for control of the hypertension of autonomic hyperreflexia ( Fig. 48.2 ).
Obstetric Management
Approximately 2000 women in the United States with spinal cord injury become pregnant each year. Pregnancy may aggravate many of the medical complications of spinal cord injury ( Box 48.1 ). The loss of both functional residual capacity and expiratory reserve volume during pregnancy may increase the likelihood of respiratory compromise associated with spinal cord injury, with worsening of respiratory function occurring as early as 20 weeks’ gestational age. Patients may require tracheal intubation and mechanical ventilatory support, and cesarean delivery may be indicated to avert the fetal risks associated with maternal hypercapnia and to improve maternal respiratory mechanics.
Pulmonary
- •
Decreased respiratory reserve
- •
Atelectasis and pneumonia
- •
Impaired cough
Hematologic
- •
Anemia
- •
Deep vein thrombosis
- •
Thromboembolic phenomena
Urogenital
- •
Chronic urinary tract infections
- •
Urinary tract calculi
- •
Proteinuria
- •
Renal insufficiency
Dermatologic
- •
Decubitus ulcers
Cardiovascular
- •
Hypertension
- •
Autonomic hyperreflexia
Pregnancy increases the risks for thromboembolic phenomena and urinary tract infection. Loss of sympathetic tone below the level of the lesion renders pregnant patients with spinal cord injury particularly prone to orthostatic hypotension, which may result in reduced uteroplacental perfusion. In pregnant women, autonomic hyperreflexia occurs most commonly during labor; uterine contractions, vaginal and cervical examinations, speculum insertion, and urethral catheterization may trigger autonomic hyperreflexia. Autonomic hyperreflexia may affect uteroplacental blood flow, necessitating careful monitoring of the fetal heart rate (FHR). Symptoms of autonomic hyperreflexia are also common in the immediate postpartum period, possibly triggered by postpartum pain, urethral catheterization, and uterine contractions.
Women with a lesion above T11 may be at higher risk for preterm labor. Because these women do not experience labor pain, obstetric management includes weekly cervical examinations during the third trimester, and patients are instructed on uterine palpation techniques to detect contractions at home. Although vaginal delivery is preferred, the development of autonomic hyperreflexia in the second stage of labor may necessitate expedited instrumental delivery. Assisted vaginal delivery may also be necessary because of the inability of the mothers to push during the second stage. In a study of 52 pregnancies in spinal cord–injured women, 9 of 12 patients with lesions above T5 had symptoms of autonomic hyperreflexia. The cesarean delivery rate was 47% for women with lesions above T5 and 26% for women with lesions at T5 or below. Preterm delivery occurred in 19% of patients.
Anesthetic Management
The ACOG recommends continuous hemodynamic monitoring during labor for all patients at risk for autonomic hyperreflexia. This syndrome can be distinguished from other causes of intrapartum hypertension by the occurrence of cyclic hypertension (i.e., blood pressure increases during contractions and decreases between contractions).
Early neuraxial anesthesia is preferred for the prevention or treatment of autonomic hyperreflexia during labor and delivery. Although neuraxial labor analgesia may attenuate the risk and symptoms of autonomic hyperreflexia, it may not ablate the phenomenon entirely, particularly when low doses of local anesthetics are used. Spinal anesthesia has effectively controlled blood pressure in paraplegic patients undergoing general surgical procedures. Although some anesthesia providers contend that distortion of the vertebral column in paraplegic patients makes it more difficult to predict and control the level of spinal anesthesia, published data do not lend support to this assumption. If spinal anesthesia is chosen, insertion of an intrathecal catheter and use of a continuous technique may be appropriate; this approach may allow careful titration of the resulting neuroblockade. Assessment of level of blockade in an insensate patient may be accomplished by assessing for loss of lower extremity deep tendon reflexes and meticulous monitoring for acute hypertension and bradycardia.
Most obstetric anesthesia providers prefer the use of epidural analgesia for the prevention or treatment of autonomic hyperreflexia during labor and vaginal delivery. Consideration also should be given to providing epidural analgesia after vaginal delivery to minimize the possibility of autonomic hyperreflexia, which has been reported to occur in response to pain as late as 5 days after delivery.
Case reports have described the successful epidural administration of 0.25% or 0.5% bupivacaine, or the administration of combined spinal-epidural (CSE) anesthesia for the mitigation of autonomic hyperreflexia. Baraka reported the successful use of epidural meperidine, an opioid with local anesthetic qualities, in avoiding the signs of autonomic hyperreflexia. Abouleish et al. observed that epidural fentanyl alone did not effectively treat the hypertension of autonomic hyperreflexia, but the addition of 0.25% bupivacaine led to a decrease in blood pressure to baseline levels. Maehama et al. described the successful use of magnesium sulfate for management of autonomic hyperreflexia during labor.
Patients with spinal cord injury often have a low baseline blood pressure and some hemodynamic instability. Placement of an intra-arterial catheter before induction of anesthesia allows the continuous assessment of blood pressure. In patients with a history of autonomic hyperreflexia, continuous hemodynamic monitoring with an intra-arterial catheter will permit early detection and treatment of symptoms. Pulse oximetry is particularly useful in patients with respiratory compromise, and the anesthesia provider should always be available to provide ventilatory assistance if necessary.
Positioning for neuraxial block may be difficult; the anesthesia provider should consider performing the block with the patient in a lateral position because the sitting position may cause hypotension from venous pooling in the lower body. Therapeutic doses of a local anesthetic agent should be administered cautiously with the understanding that the cephalad level of the sensory block can be fully assessed only if it is higher than the level of the spinal cord lesion. As a result, the typical epidural test dose may not identify unintentional subarachnoid injection in a patient with spinal cord injury. Neuraxial blockade can be partially assessed by evaluating segmental reflexes below the level of the lesion. For example, the anesthesia provider can lightly stroke each side of the abdomen above and below the umbilicus, looking for contraction of the abdominal muscles and deviation of the umbilicus toward the stimulus. Reflexes are absent below the level of the block. In some patients with spastic paresis at baseline, the level of anesthesia may be confirmed by the conversion of spastic paresis to flaccid paresis. A decline in blood pressure may also herald the onset of neuraxial blockade.
Alternative means of treating autonomic hyperreflexia should be available at the bedside if neuraxial analgesia or anesthesia is inadequate or not successful. Antihypertensive medications such as magnesium sulfate or arteriolar vasodilators may be effective, recognizing that hypotension can result in decreased uterine blood flow. Careful titration of sodium nitroprusside, noting the potential for fetal/neonatal cyanide intoxication, or beta-adrenergic receptor blockade, may also be useful. The anesthesia provider should recognize that increased vagal activity during autonomic hyperreflexia can result in electrocardiographic changes including first- and second-degree atrioventricular block and sinus arrest.
If cesarean delivery is necessary, epidural or spinal anesthesia can be administered. Spinal anesthesia is generally associated with more rapid onset and greater need to treat hypotension. The effect of neuraxial blockade on respiratory function may be less severe with epidural anesthesia than with spinal anesthesia.
Severe respiratory insufficiency or technical difficulties with neuraxial anesthesia may necessitate the use of general anesthesia. If general anesthesia is required, a depolarizing muscle relaxant such as succinylcholine should not be given during the period of denervation injury. By a conservative definition, this period begins 24 hours after the injury and lasts for 1 year. The use of succinylcholine during this period of denervation injury may cause severe hyperkalemia ; therefore, a nondepolarizing muscle relaxant should be used to facilitate laryngoscopy and tracheal intubation.
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