Neurology of pregnancy

The role of gonadal hormones in regulating opioid antinociception

Opioids are the most prescribed drugs for the alleviation of pain. Both clinical and preclinical studies have reported strong evidence for sex-related divergence regarding opioid analgesia. There is an increasing amount of evidence indicating that gonadal hormones regulate the analgesic efficacy of opioids. This review presents an overview of the importance of gonadal steroids in modulating opioid analgesic responsiveness and focuses on elaborating what is currently known regarding the underlyingmechanism. We sought to identify the link between gonadal hormones and the effect of oipiod antinociception.

Histological analysis of neuronal changes in the olfactory cortex during pregnancy

Fluctuations in olfactory sensitivity are widely known to occur during pregnancy and may be responsible for hyperemesis gravidarum. These changes are thought to be caused by structural and functional alterations in neurons in response to marked changes of the hormonal milieu. In this study, we examined changes in neurons in the olfactory cortex during pregnancy and after delivery in rats. Dendritic spine densities were measured in the piriform cortex (PIR) and posterolateral cortical amygdala (COApl), which are involved in olfaction. The results showed increased numbers of dendritic spines in the PIR in mid-pregnancy and in the COApl during early and late pregnancy, but not in the motor area of the cerebral cortex, indicating a correlation with changes in olfactory sensitivity during pregnancy. Immunohistochemical analysis of expression of ovarian hormone receptors in these brain regions revealed a decrease in the number of estrogen receptor α-positive cells during pregnancy in the PIR and during pregnancy and the postpartum period in the COApl. Regarding pregnancy-related peptide hormones, oxytocin receptors were expressed in the PIR and COApl, while prolactin receptors were not found in these regions. Accordingly, oxytocin-containing neurites were distributed in both regions. These results suggest that the balance of these hormonal signals has an effect on olfactory sensitivity in pregnant females.

Exercise-Induced Hypoalgesia in Patients with Chronic Whiplash-Associated Disorders: Differences between Subgroups Based on the Central Sensitization Inventory

BACKGROUND

Physical exercise is an important element in the rehabilitation of chronic whiplash-associated disorders, with the physiological process underlying pain reduction called exercise-induced hypoalgesia. In chronic whiplash-associated disorders, exercise-induced hypoalgesia appears impaired, and the research suggests a relationship with symptoms of dysfunctional nociceptive processing, such as central sensitization. This study improves our understanding of exercise-induced hypoalgesia in chronic whiplash-associated disorders by examining the differences between the extent of exercise-induced hypoalgesia in subgroups based on scores on the central sensitization inventory (CSI).

METHODS

Data were collected from 135 participants with chronic whiplash-associated disorders who completed a set of questionnaires. Pain pressure thresholds and temporal summations were assessed before and after a submaximal aerobic bicycle exercise test.

RESULTS

We observed no interaction effect between exercise-induced hypoalgesia and the CSI scores for both pain pressure threshold and temporal summation. No overall statistical effect was measured in the analysis of the effect of time. The pain pressure threshold significantly related to the CSI. The temporal summation showed no correlation.

CONCLUSIONS

During this study, we did not find evidence for a difference in the presence of exercise-induced hypoalgesia when the subgroups were created based on the central sensitization cluster calculator. Limited evidence was found for the influence of CSI scores on the delta pain pressure threshold.

Neurologic Complication Due to Crystallization After Drug Interaction Between Alkalized Lidocaine and Ropivacaine: A Case Report and in vitro Study

Background

For pregnant women transferred to emergency cesarean section after receiving epidural labor analgesia, there is still a debate over the effective and safe means of rapidly delivering surgical anesthesia. Alkalized lidocaine is often adopted for fast onset time; however, crystallization of the anesthetic may cause severe neurologic symptoms.

Case Presentation

We report a case of a pregnant woman who underwent emergency cesarean section with satisfied analgesia but experienced severe weakness and paranaesthesia in the lower limb. After excluding lumbar disc herniation, obstetric nerve injury, and anesthesia technique causes by symptoms signs and magnetic resonance imaging, drug-related injury became the most likely cause. Our in vitro testing confirmed the obvious precipitation of additional anesthetic-concentrated ropivacaine (0.5–1%) with pretreated alkalized lidocaine. With trophic neurotherapy, the parturient attained prompt relief of weakness by day four, but delayed recovery of numbness, which lasted for 4 weeks.

Conclusion

To date, this is the first case reporting neurologic complication possibly due to drug crystallization in cesarean section. Our study confirmed the rapid onset of alkalized lidocaine and its safety to pretreated routine labor dose of ropivacaine (0.09%). However, additional anesthetic-concentrated ropivacaine (0.5–1%) to maintain the anesthesia and analgesia level is not suggested.

Effect of Preeclampsia on Ultrastructure of Thyroid Gland, Hepatic Type 1 Iodothyronine Deiodinase, and Thyroid Hormone Levels in Rats

Background

Although hypothyroidism during pregnancy may develop grave outcomes for both mothers and offspring, management of which is still a challenge due to the insufficient understanding of this disease. The close correlation between hypothyroidism and preeclampsia is well documented, suggesting that preeclampsia is a potential risk factor for the development of maternal hypothyroidism. However, the exact role of preeclampsia in gestational hypothyroidism is still obscure.

Objective

In this study, we explored the possible mechanisms of the effect of preeclampsia on thyroid function of maternal rats.

Methods

Thirty pregnant rats were randomly divided into normal pregnancy control (NOP), preeclampsia (PE), and preeclampsia supplemented with amlodipine besylate (PEAml). NG-Nitro-L-arginine-methyl ester was used to induce preeclamptic symptoms. On gestational day 21, rats were sacrificed, and then, the ultrastructure of the thyroid gland, type 1 iodothyronine deiodinase (Dio1) expression, and serum-free thyroxine (FT₄), free triiodothyronine (FT₃), and thyroid stimulation hormones (TSH) were assessed.

Results

Compared to NOP rats, results of PE rats showed that thyroid follicular cells' ultrastructure was damaged; both hepatic Dio1 mRNA and protein levels were decreased. Interestingly, these changes were ameliorated in PEAml rats. Additionally, FT₄, FT₃, and TSH levels have no significant differences among groups.

Conclusion

These findings indicated that preeclampsia could disrupt synthesis, secretion, and metabolism function of thyroid hormones by damaging thyroid follicular cells and interfering Dio1 expression.

Stroke in pregnancy

Stroke in pregnancy is rare and has a wide range of etiologies and implications on stroke management that differ from nonpregnant individuals. The highest risk of stroke is during the third trimester and puerperium period, where hypertensive disorders of pregnancy occur; however, stroke can occur at any point during pregnancy. In this chapter, we will provide an overview of the epidemiology of stroke in pregnancy and then review the specific etiologies of ischemic and hemorrhagic stroke as they relate to pregnant women. Finally, we discuss the process of acute stroke evaluation in pregnancy and the management of women after stroke with regard to long-term risk factors, medications, and implications in future pregnancies. Throughout the chapter, we highlight relevant guidelines from the American Heart Association and American Stroke Association and key literature on stroke in pregnancy.

Convergent Validity of the Central Sensitization Inventory in Chronic Whiplash-Associated Disorders; Associations with Quantitative Sensory Testing, Pain Intensity, Fatigue, and Psychosocial Factors

OBJECTIVE

Central sensitization is present in different pain conditions, including chronic whiplash-associated disorders. In the absence of a gold standard method of assessment to determine the presence of central sensitization, quantitative sensory testing is currently understood as an optimal proxy. Laboratory sensory testing is, however, not feasible in clinical practice, and the Central Sensitization Inventory was developed as an alternative. The aim of the current study was to evaluate the convergent validity of the Central Sensitization Inventory in chronic whiplash-associated patients by determining the association between the Central Sensitization Inventory and quantitative sensory testing, pain intensity, fatigue, and psychosocial factors.

METHODS

A total of 125 chronic whiplash-associated patients completed multiple questionnaires and were subjected to pressure pain thresholds and temporal summation.

RESULTS

. The Central Sensitization Inventory showed a strong association with constructs of general psychopathology, anxiety, distress, depression, and somatization in chronic whiplash-associated disorders. Moderate correlations were found with fatigue and intrusive and avoidant phenomena after a variety of traumatic events. No significant association was found between the Central Sensitization Inventory and pressure pain thresholds and temporal summation, nor between the Central Sensitization Inventory and other pain measurements.

CONCLUSIONS

Overall, we found that the Central Sensitization Inventory is better in identifying the psychosocial factors related to central sensitization in chronic whiplash-associated disorders than the central nervous system adaptations. Thus, the convergent validity of the Central Sensitization Inventory appears to be only partially present in chronic whiplash-associated disorders.

Optic nerve sheath diameter: present and future perspectives for neurologists and critical care physicians

BACKGROUND

Estimation of intracranial pressure (ICP) may be helpful in the management of neurological critically ill patients. It has been shown that ultrasonography of the optic nerve sheath diameter (ONSD) is a reliable tool for non-invasive estimation of increased intracranial pressure (ICP) at hospital admission or in intensive care. Less is known about the estimation of increased ICP and usefulness of ONSD in the prehospital setting. The aim of this review was to elucidate both prevailing and novel applications of ONSD for neurologists and critical care physicians.

METHODS

In this review, we discuss the technique and the novel approach of ONSD measurement, the clinical applications of ONSD in neurology and critical care patients.

RESULTS

ONSD measurement is simple, easy to learn, and has diverse applications. ONSD has utility for ICP measurement in intracranial hemorrhage and ischemic stroke, meningitis and encephalitis, and idiopathic intracranial hypertension (IIH). It is also valuable for lesser known syndromes, where an increase of ICP is postulated, such as acute mountain sickness and posterior reversible encephalopathy syndrome. ONSD changes develop in inflammatory or ischemic optic neuropathies. Some papers demonstrate the usefulness of ONSD studies in symptomatic intracranial hypotension.

CONCLUSIONS

ONSD is a safe and low-cost bedside tool with the potential of screening patients who need other neuroimaging and those who may need an invasive measurement of ICP.

Post-partum posterior reversible encephalopathy syndrome requiring decompressive craniectomy: case report and review of the literature

Posterior reversible encephalopathy syndrome (PRES) is an uncommon but potentially devastating syndrome if not recognized and treated appropriately. As the name implies, recognition of the condition and proper management may reverse the clinical and radiological findings. However, diagnosis is not always straightforward. We present the case of a 24-year-old female who was 4 days post-partum and presented with headache, neck pain, and new-onset seizures. She had undergone epidural anesthesia during labor, and initial imaging was suggestive of intracranial hypotension versus pachymeningitis. Despite initial conservative therapy including anti-epileptic drugs, magnesium therapy, empiric antibiotics, and Trendelenburg positioning, the patient continued to deteriorate. Follow-up imaging was suggestive of PRES with signs of intracranial hypertension. The patient underwent a decompressive suboccipital craniectomy for refractory and severe PRES and later fully recovered. This case highlights the sometimes difficult diagnosis of PRES, possible association with pregnancy, eclampsia/preeclampsia and/or cerebrospinal fluid drainage, and the rare but life-saving need for decompression in severe cases.

Neurofilament as Neuronal Injury Blood Marker in Preeclampsia

Preeclampsia has been shown to be associated with changes in cerebral structure and cognitive function later in life. Nf (neurofilaments) are specific scaffolding proteins of neurons, and their quantification in serum has been proposed as a biomarker for neuroaxonal injury. We performed a prospective, longitudinal, single-center study at the University Hospital of Basel to determine serum Nf concentrations in pregnant women with singleton pregnancies and with high risk of preeclampsia or with early signs of preeclampsia. Enrollment started at 21 weeks of gestation, followed up with multiple visits until delivery. Sixty out of 197 women developed preeclampsia (30.5%). NfL (Nf light chain) was measured with a highly sensitive single molecule array (Simoa) assay, in addition to the established preeclampsia markers sFlt-1 (soluble fms-like tyrosine kinase-1) and PlGF (placental growth factor). The most important independent predictors of NfL were maternal age, number of pregnancies, and proteinuria. NfL levels increased during pregnancy and were significantly higher in women developing preeclampsia. The discriminatory accuracy of NfL, PlGF, and sFlt-1 in receiver operating characteristic curves analysis (area under the curve) of the overall group was 0.68, 0.81, and 0.84, respectively, and in women older than 36 years 0.7, 0.62, and 0.79, respectively. We conclude that increased axonal injury serum marker NfL predicts preeclampsia particularly in older women, with an accuracy similar to the established angiogenic factors. NfL may serve as an early indicator of preeclampsia-induced changes in cerebral structure and may help to stratify disease management.

T-Cell Mediation of Pregnancy Analgesia Affecting Chronic Pain in Mice

It has been reported consistently that many female chronic pain sufferers have an attenuation of symptoms during pregnancy. Rats display increased pain tolerance during pregnancy due to an increase in opioid receptors in the spinal cord. Past studies did not consider the role of non-neuronal cells, which are now known to play an important role in chronic pain processing. Using an inflammatory (complete Freund's adjuvant) or neuropathic (spared nerve injury) model of persistent pain, we observed that young adult female mice in early pregnancy switch from a microglia-independent to a microglia-dependent pain hypersensitivity mechanism. During late pregnancy, female mice show no evidence of chronic pain whatsoever. This pregnancy-related analgesia is reversible by intrathecal administration of naloxone, suggesting an opioid-mediated mechanism; pharmacological and genetic data suggest the importance of δ-opioid receptors. We also observe that T-cell-deficient (nude and Rag1-null mutant) pregnant mice do not exhibit pregnancy analgesia, which can be rescued with the adoptive transfer of CD4⁺ or CD8⁺ T cells from late-pregnant wild-type mice. These results suggest that T cells are a mediator of the opioid analgesia exhibited during pregnancy.SIGNIFICANCE STATEMENT Chronic pain symptoms often subside during pregnancy. This pregnancy-related analgesia has been demonstrated for acute pain in rats. Here, we show that pregnancy analgesia can produce a complete cessation of chronic pain behaviors in mice. We show that the phenomenon is dependent on pregnancy hormones (estrogen and progesterone), δ-opioid receptors, and T cells of the adaptive immune system. These findings add to the recent but growing evidence of sex-specific T-cell involvement in chronic pain processing.

Maternal clinical disease characteristics and maternal and neonatal outcomes in twin and singleton pregnancies with severe preeclampsia

OBJECTIVE

Based on anecdotal observations, there is concern that severe preeclampsia leads to greater morbidity and mortality for mothers and neonates of twin pregnancies than for mothers and neonates of singleton pregnancies. Because few studies have been done, this study compared maternal disease characteristics and maternal/neonatal clinical outcomes of twin and singleton pregnancies complicated by severe preeclampsia.

STUDY DESIGN

An historical cohort study of patients hospitalized at the Mount Sinai Hospital in New York City, NY, USA, from 2006 to 2010, compared 63 twin and 339 singleton pregnancies complicated by severe preeclampsia via chart review. Women were analyzed in two groups: hospitalized ≤34 weeks gestational age (GA) and hospitalized >34 weeks GA. Univariable analysis (using Chi-square test, Fisher's Exact test, Student's t-test, or Wilcoxon Rank-Sum test, as appropriate) then multivariable analysis (using multivariable linear regression or multivariable logistic regression, as appropriate) compared maternal disease characteristics and maternal/neonatal clinical outcomes in twin and singleton pregnancies.

RESULTS

Women with twins were older [mean age 34.9 years (standard deviation (SD) 7.9 years) vs. 29.4 years (SD 7.4 years), P-value<.001] and women with singletons had a higher prevalence of chronic hypertension (21% vs. 8%, P=.02) and higher prevalence of history of preeclampsia (13% vs. 2%, P=.006). Women with twins were admitted for severe preeclampsia at an earlier gestational age (GA) [median twin 34.9 weeks GA (interquartile range, IQR, 32.7, 36.1) vs. median singleton 37.1 weeks GA (IQR 35.0, 38.9), P<.001]. Among women presenting ≤34 weeks GA (27 twins; 108 singletons), women with singletons had a higher mean systolic blood pressure (BP) (181.1 vs. 163.5, P<.001), higher mean diastolic BP (108.4 vs. 100.1, P=.002), and higher prevalence of headache (56% vs. 30%, P=.02). Among women presenting >34 weeks GA (36 twins; 231 singletons), women with singletons had a higher prevalence of headache (54% vs. 28%, P=.004).

CONCLUSION

Mothers and neonates of twin pregnancies complicated by severe preeclampsia do not appear to have greater morbidity and mortality compared to mothers and neonates of singleton pregnancies complicated by severe preeclampsia.