Pathogenic RHEB Somatic Variant in a Child With Tuberous Sclerosis Complex Without Pathogenic Variants in TSC1 or TSC2

OBJECTIVE

To describe a child meeting diagnostic criteria for tuberous sclerosis complex (TSC) carrying a pathogenic somatic variant in RHEB, but no pathogenic variants in the two known TSC genes, TSC1 or TSC2.

METHODS

We present the clinical and imaging findings in a child presenting with drug-resistant focal seizures and multiple cortical tubers, a subependymal giant cell astrocytoma and multiple subependymal nodules in one cerebral hemisphere. Targeted panel sequencing and exome sequencing were performed on genomic DNA derived from blood and resected tuber tissue.

RESULTS

The child satisfied clinical diagnostic criteria for TSC, having three major features, only two of which are required for diagnosis. Genetic testing did not identify pathogenic variants or copy number variations in TSC1 or TSC2, but identified a pathogenic somatic RHEB variant (NM_005614.4:c.104_105delACinsTA [p.Tyr35Leu]) in the cortical tuber.

DISCUSSION

RHEB is a partner of the TSC1/2 complex in the mechanistic target of rapamycin pathway. Somatic variants in RHEB are associated with focal cortical dysplasia and hemimegalencephaly. We propose that variants in RHEB may explain some of the genetically undiagnosed TSC cases and may be the third gene for TSC or TSC3.

Basal ganglia dysplasia and mTORopathy: A potential cause of postoperative seizures in focal cortical dysplasia

Pathogenic somatic MTOR variants in the cerebral cortex are a frequent cause of focal cortical dysplasia (FCD). We describe a child with drug and surgery-resistant focal epilepsy due to FCD type II who developed progressive enlargement and T2 signal hyperintensity in the ipsilateral caudate and lentiform nuclei. Histopathology of caudate nucleus biopsies showed dysmorphic neurons, similar to those in resected cortex. Genetic analysis of frontal and temporal cortex and caudate nucleus identified a pathogenic somatic MTOR variant [NM_004958.4:c.4375G > C (p.Ala1459Pro)] that was not present in blood-derived gDNA. The mean variant allele frequency ranged from 0.4% to 3.2% in cerebral cortex and up to 5.4% in the caudate nucleus. The basal ganglia abnormalities suggest more widespread, potentially hemispheric dysplasia in this patient, consistent with the pathogenic variant occurring in early cerebral development. This finding provides a potential explanation for persistent seizures in some patients with seemingly complete resection of FCD or disconnection of a dysplastic hemisphere.

Assessment of intraoperative diffusion EPI distortion and its impact on estimation of supratentorial white matter tract positions in pediatric epilepsy surgery

The effectiveness of correcting diffusion Echo Planar Imaging (EPI) distortion and its impact on tractography reconstruction have not been adequately investigated in the intraoperative MRI setting, particularly for High Angular Resolution Diffusion Imaging (HARDI) acquisition. In this study, we evaluated the effectiveness of EPI distortion correction using 27 legacy intraoperative HARDI datasets over two consecutive surgical time points, acquired without reverse phase-encoded data, from 17 children who underwent epilepsy surgery at our institution. The data was processed with EPI distortion correction using the Synb0-Disco technique (Schilling et al., 2019) and without distortion correction. The corrected and uncorrected b0 diffusion-weighted images (DWI) were first compared visually. The mutual information indices between the original T1-weighted images and the fractional anisotropy images derived from corrected and uncorrected DWI were used to quantify the effect of distortion correction. Sixty-four white matter tracts were segmented from each dataset, using a deep-learning based automated tractography algorithm for the purpose of a standardized and unbiased evaluation. Displacement was calculated between tracts generated before and after distortion correction. The tracts were grouped based on their principal morphological orientations to investigate whether the effects of EPI distortion vary with tract orientation. Group differences in tract distortion were investigated both globally, and regionally with respect to proximity to the resecting lesion in the operative hemisphere. Qualitatively, we observed notable improvement in the corrected diffusion images, over the typically affected brain regions near skull-base air sinuses, and correction of additional distortion unique to intraoperative open cranium images, particularly over the resection site. This improvement was supported quantitatively, as mutual information indices between the FA and T1-weighted images were significantly greater after the correction, compared to before the correction. Maximum tract displacement between the corrected and uncorrected data, was in the range of 7.5 to 10.0 mm, a magnitude that would challenge the safety resection margin typically tolerated for tractography-informed surgical guidance. This was particularly relevant for tracts oriented partially or fully in-line with the acquired diffusion phase-encoded direction. Portions of these tracts passing close to the resection site demonstrated significantly greater magnitude of displacement, compared to portions of tracts remote from the resection site in the operative hemisphere. Our findings have direct clinical implication on the accuracy of intraoperative tractography-informed image guidance and emphasize the need to develop a distortion correction technique with feasible intraoperative processing time.

Cerebrospinal fluid liquid biopsy for detecting somatic mosaicism in brain

Brain somatic mutations are an increasingly recognized cause of epilepsy, brain malformations and autism spectrum disorders and may be a hidden cause of other neurodevelopmental and neurodegenerative disorders. At present, brain mosaicism can be detected only in the rare situations of autopsy or brain biopsy. Liquid biopsy using cell-free DNA derived from cerebrospinal fluid has detected somatic mutations in malignant brain tumours. Here, we asked if cerebrospinal fluid liquid biopsy can be used to detect somatic mosaicism in non-malignant brain diseases. First, we reliably quantified cerebrospinal fluid cell-free DNA in 28 patients with focal epilepsy and 28 controls using droplet digital PCR. Then, in three patients we identified somatic mutations in cerebrospinal fluid: in one patient with subcortical band heterotopia the LIS1 p. Lys64* variant at 9.4% frequency; in a second patient with focal cortical dysplasia the TSC1 p. Phe581His*6 variant at 7.8% frequency; and in a third patient with ganglioglioma the BRAF p. Val600Glu variant at 3.2% frequency. To determine if cerebrospinal fluid cell-free DNA was brain-derived, whole-genome bisulphite sequencing was performed and brain-specific DNA methylation patterns were found to be significantly enriched (P = 0.03). Our proof of principle study shows that cerebrospinal fluid liquid biopsy is valuable in investigating mosaic neurological disorders where brain tissue is unavailable.

Gradient of brain mosaic RHEB variants causes a continuum of cortical dysplasia

Focal cortical dysplasia (FCD) and hemimegalencephaly (HME) are related malformations with shared etiologies. We report three patients with a spectrum of cortical malformations associated with pathogenic brain-specific somatic Ras homolog enriched in brain (RHEB) variants. The somatic variant load directly correlated with the size of the malformation, with upregulated mTOR activity confirmed in dysplastic tissues. Laser capture microdissection showed enrichment of RHEB variants in dysmorphic neurons and balloon cells. Our findings support the role of RHEB in a spectrum of cortical malformations confirming that FCD and HME represent a disease continuum, with the extent of dysplastic brain directly correlated with the somatic variant load.

Rationale, design, and methods of a randomized, controlled, open-label clinical trial with open-label extension to investigate the safety of vosoritide in infants, and young children with achondroplasia at risk of requiring cervicomedullary decompression surgery

Achondroplasia causes narrowing of the foramen magnum and the spinal canal leading to increased mortality due to cervicomedullary compression in infants and significant morbidity due to spinal stenosis later in adulthood. Vosoritide is a C-natriuretic peptide analogue that has been shown to improve endochondral ossification in children with achondroplasia. The objective of this trial is to evaluate the safety of vosoritide and whether vosoritide can improve the growth of the foramen magnum and spinal canal in children that may require decompression surgery. An Achondroplasia Foramen Magnum Score will be used to identify infants at risk of requiring decompression surgery. This is a 2-year open label randomized controlled trial of vosoritide in infants with achondroplasia ages 0 to ≤12 months. Approximately 20 infants will be randomized 1:1 to either open label once daily subcutaneous vosoritide combined with standard of care or standard of care alone. The primary and secondary aims of the study are to evaluate the safety and efficacy of vosoritide in children with cervicomedullary compression at risk of requiring decompression surgery. The trial will be carried out in specialized skeletal dysplasia treatment centers with well established multidisciplinary care pathways and standardized approaches to the neurosurgical management of cervicomedually compression. After 2 years, infants randomized to standard of care alone will be eligible to switch to vosoritide plus standard of care for an additional 3 years. This pioneering trial hopes to address the important question as to whether treatment with vosoritide at an early age in infants at risk of requiring cervicomedullary decompression surgery is safe, and can improve growth at the foramen magnum and spinal canal alleviating stenosis. This in turn may reduce compression of surrounding structures including the neuraxis and spinal cord, which could alleviate future morbidity and mortality.Trial registrations: ClinicalTrials.gov, NCT04554940; EudraCT number, 2020-001055-40.

Genetic characterization identifies bottom-of-sulcus dysplasia as an mTORopathy

OBJECTIVE

To determine the genetic basis of bottom-of-sulcus dysplasia (BOSD), which is a highly focal and epileptogenic cortical malformation in which the imaging, electrophysiologic, and pathologic abnormalities are maximal at the bottom of sulcus, tapering to a normal gyral crown.

METHODS

Targeted panel deep sequencing (>500×) was performed on paired blood and brain-derived genomic DNA from 20 operated patients with drug-resistant focal epilepsy and BOSD. Histopathology was assessed using immunohistochemistry.

RESULTS

Brain-specific pathogenic somatic variants were found in 6 patients and heterozygous pathogenic germline variants were found in 2. Somatic variants were identified in MTOR and germline variants were identified in DEPDC5 and NPRL3. Two patients with somatic MTOR variants showed a mutation gradient, with higher mutation load at the bottom of sulcus compared to the gyral crown. Immunohistochemistry revealed an abundance of dysmorphic neurons and balloon cells in the bottom of sulcus but not in the gyral crown or adjacent gyri.

CONCLUSIONS

BOSD is associated with mTOR pathway dysregulation and shares common genetic etiologies and pathogenic mechanisms with other forms of focal and hemispheric cortical dysplasia, suggesting these disorders are on a genetic continuum.

Second-hit DEPDC5 mutation is limited to dysmorphic neurons in cortical dysplasia type IIA

Focal cortical dysplasia (FCD) causes drug‐resistant epilepsy and is associated with pathogenic variants in mTOR pathway genes. How germline variants cause these focal lesions is unclear, however a germline + somatic “2‐hit” model is hypothesized. In a boy with drug‐resistant epilepsy, FCD, and a germline DEPDC5 pathogenic variant, we show that a second‐hit DEPDC5 variant is limited to dysmorphic neurons, and the somatic mutation load correlates with both dysmorphic neuron density and the epileptogenic zone. These findings provide new insights into the molecular and cellular correlates of FCD determining drug‐resistant epilepsy and refine conceptualization of the epileptogenic zone.

Somatic GNAQ mutation in the forme fruste of Sturge-Weber syndrome

Objective

To determine whether the GNAQ R183Q mutation is present in the forme fruste cases of Sturge-Weber syndrome (SWS) to establish a definitive molecular diagnosis.

Methods

We used sensitive droplet digital PCR (ddPCR) to detect and quantify the GNAQ mutation in tissues from epilepsy surgery in 4 patients with leptomeningeal angiomatosis; none had ocular or cutaneous manifestations.

Results

Low levels of the GNAQ mutation were detected in the brain tissue of all 4 cases—ranging from 0.42% to 7.1% frequency—but not in blood-derived DNA. Molecular evaluation confirmed the diagnosis in 1 case in which the radiologic and pathologic data were equivocal.

Conclusions

We detected the mutation at low levels, consistent with mosaicism in the brain or skin (1.0%–18.1%) of classic cases. Our data confirm that the forme fruste is part of the spectrum of SWS, with the same molecular mechanism as the classic disease and that ddPCR is helpful where conventional diagnosis is uncertain.

Potential delays in referral and assessment for epilepsy surgery in children with drug-resistant, early-onset epilepsy

OBJECTIVE

To study potential delays in epilepsy surgery in children with drug-resistant epilepsy (DRE) of early-onset.

METHODS

Medical records were reviewed from 87 children with DRE and seizure onset before age 3 years who underwent epilepsy surgery between 2006 and 2015. Information was obtained about each child's epilepsy, treatment and specific time points in management. Time intervals along diagnostic, investigative, treatment and referral pathways were calculated.

RESULTS

Median ages at seizure onset, when seen in the epilepsy surgery program and surgery were 5.9 (IQR 10), 19 (IQR 29) and 36 (IQR 67) months; the median delay from seizure onset to surgery was 30 (IQR 67) months. Most children were promptly diagnosed, treated, investigated and seen by a pediatric neurologist. Focal abnormalities were reported on initial EEGs and MRIs in most children, and DRE developed within a median of 6.3 months from commencement of medication. There were median durations of 6.2 months between seeing a neurologist and being seen in the epilepsy surgery program, and then 6.1 months in determining surgical candidacy. Median durations from potential indications for a surgical evaluation to agreed surgical candidacy were 10 (DRE), 12 (focal MRI) and 17 (focal EEG) months. Children received a median of six antiepileptic drugs prior to surgery. Median interval from agreed surgical candidacy to surgery was only 3 months. There were longer durations from seizure onset to surgery in children needing PET (p = 0.001) and in children with seizure-free periods (p < 0.001), and shorter durations in children with a history of infantile spasms (p = 0.01).

SIGNIFICANCE

Delays in referral of children for epilepsy surgery are reported. Delays in assessment may be specific to centralized children's hospitals in public health systems.

Spontaneous painful disease in companion animals can facilitate the development of chronic pain therapies for humans

OBJECTIVE

To outline the role that spontaneous osteoarthritis (OA) in companion animals can play in translational research and therapeutic pharmacological development.

OUTLINE

Narrative review summarizing the opportunities and limitations of naturally occurring, spontaneous OA as models of human OA pain, with a focus on companion animal pets. The background leading to considering inserting spontaneous disease models in the translational paradigm is provided. The utility of this model is discussed in terms of outcome measures that have been validated as being related to pain, and in terms of the potential for target discovery is outlined. The limitations to using companion animal pets as models of human disease are discussed.

CONCLUSIONS

Although many steps along the translational drug development pathway have been identified as needing improvement, spontaneous painful OA in companion animals offers translational potential. Such 'models' may better reflect the complex genetic, environmental, temporal and physiological influences present in humans and current data suggests the predictive validity of the models are good. The opportunity for target discovery exists but is, as yet, unproven.

GWAS Identifies New Loci for Painful Temporomandibular Disorder: Hispanic Community Health Study/Study of Latinos

Temporomandibular disorder (TMD) is a musculoskeletal condition characterized by pain and reduced function in the temporomandibular joint and/or associated masticatory musculature. Prevalence in the United States is 5% and twice as high among women as men. We conducted a discovery genome-wide association study (GWAS) of TMD in 10,153 participants (769 cases, 9,384 controls) of the US Hispanic Community Health Study/Study of Latinos (HCHS/SOL). The most promising single-nucleotide polymorphisms (SNPs) were tested in meta-analysis of 4 independent cohorts. One replication cohort was from the United States, and the others were from Germany, Finland, and Brazil, totaling 1,911 TMD cases and 6,903 controls. A locus near the sarcoglycan alpha ( SGCA), rs4794106, was suggestive in the discovery analysis ( P = 2.6 × 10⁶) and replicated (i.e., 1-tailed P = 0.016) in the Brazilian cohort. In the discovery cohort, sex-stratified analysis identified 2 additional genome-wide significant loci in females. One lying upstream of the relaxin/insulin-like family peptide receptor 2 ( RXP2) (chromosome 13, rs60249166, odds ratio [OR] = 0.65, P = 3.6 × 10^-8) was replicated among females in the meta-analysis (1-tailed P = 0.052). The other (chromosome 17, rs1531554, OR = 0.68, P = 2.9 × 10^-8) was replicated among females (1-tailed P = 0.002), as well as replicated in meta-analysis of both sexes (1-tailed P = 0.021). A novel locus at genome-wide level of significance (rs73460075, OR = 0.56, P = 3.8 × 10^-8) in the intron of the dystrophin gene DMD (X chromosome), and a suggestive locus on chromosome 7 (rs73271865, P = 2.9 × 10^-7) upstream of the Sp4 Transcription Factor ( SP4) gene were identified in the discovery cohort, but neither of these was replicated. The SGCA gene encodes SGCA, which is involved in the cellular structure of muscle fibers and, along with DMD, forms part of the dystrophin-glycoprotein complex. Functional annotation suggested that several of these variants reside in loci that regulate processes relevant to TMD pathobiologic processes.

Ictal unilateral blinking is an unreliable lateralizing sign in tuberous sclerosis complex

OBJECTIVE

Ictal unilateral blinking is an uncommon but reportedly reliable lateralizing sign, indicating an ipsilateral seizure focus. We aimed to determine its lateralizing utility in patients with tuberous sclerosis complex (TSC).

METHODS

We reviewed the video-EEGs of 92 children with TSC and drug-resistant epilepsy. Eleven (12%) had seizures with unilateral blinking, of which 10 underwent epilepsy surgery. Lateralization of seizures was inferred from other semiology, ictal scalp EEG and outcome following tuberectomy.

RESULTS

Seizures manifesting with unilateral blinking were focal motor in four patients, focal motor evolving into epileptic spasms in six, and epileptic spasms with focal features in one. Associated unilateral facial contraction was seen in five patients and arm jerking in four. Lateralized scalp ictal rhythms were seen in seven patients. Following tuberectomies, seven patients are seizure free and two had >90% reduction. Overall lateralization of seizures with unilateral blinking was contralateral in six patients and ipsilateral in four. When unilateral blinking was early in seizures, overall lateralization was more often contralateral (6/7 patients, PPV 85%).

SIGNIFICANCE

Ictal unilateral blinking is not infrequent but unreliable in lateralizing seizures in TSC. Unrecognized seizure propagation to contralateral symptomatogenic regions and potentially different mechanisms may account for the variable lateralization.

Painful Temporomandibular Disorder: Decade of Discovery from OPPERA Studies

In 2006, the OPPERA project (Orofacial Pain: Prospective Evaluation and Risk Assessment) set out to identify risk factors for development of painful temporomandibular disorder (TMD). A decade later, this review summarizes its key findings. At 4 US study sites, OPPERA recruited and examined 3,258 community-based TMD-free adults assessing genetic and phenotypic measures of biological, psychosocial, clinical, and health status characteristics. During follow-up, 4% of participants per annum developed clinically verified TMD, although that was a "symptom iceberg" when compared with the 19% annual rate of facial pain symptoms. The most influential predictors of clinical TMD were simple checklists of comorbid health conditions and nonpainful orofacial symptoms. Self-reports of jaw parafunction were markedly stronger predictors than corresponding examiner assessments. The strongest psychosocial predictor was frequency of somatic symptoms, although not somatic reactivity. Pressure pain thresholds measured at cranial sites only weakly predicted incident TMD yet were strongly associated with chronic TMD, cross-sectionally, in OPPERA's separate case-control study. The puzzle was resolved in OPPERA's nested case-control study where repeated measures of pressure pain thresholds revealed fluctuation that coincided with TMD's onset, persistence, and recovery but did not predict its incidence. The nested case-control study likewise furnished novel evidence that deteriorating sleep quality predicted TMD incidence. Three hundred genes were investigated, implicating 6 single-nucleotide polymorphisms (SNPs) as risk factors for chronic TMD, while another 6 SNPs were associated with intermediate phenotypes for TMD. One study identified a serotonergic pathway in which multiple SNPs influenced risk of chronic TMD. Two other studies investigating gene-environment interactions found that effects of stress on pain were modified by variation in the gene encoding catechol O-methyltransferase. Lessons learned from OPPERA have verified some implicated risk factors for TMD and refuted others, redirecting our thinking. Now it is time to apply those lessons to studies investigating treatment and prevention of TMD.

Familial cortical dysplasia caused by mutation in the mammalian target of rapamycin regulator NPRL3

We describe first cousin sibling pairs with focal epilepsy, one of each pair having focal cortical dysplasia (FCD) IIa. Linkage analysis and whole-exome sequencing identified a heterozygous germline frameshift mutation in the gene encoding nitrogen permease regulator-like 3 (NPRL3). NPRL3 is a component of GAP Activity Towards Rags 1, a negative regulator of the mammalian target of rapamycin complex 1 signaling pathway. Immunostaining of resected brain tissue demonstrated mammalian target of rapamycin activation. Screening of 52 unrelated individuals with FCD identified 2 additional patients with FCDIIa and germline NPRL3 mutations. Similar to DEPDC5, NPRL3 mutations may be considered as causal variants in patients with FCD or magnetic resonance imaging-negative focal epilepsy.

COMT Diplotype Amplifies Effect of Stress on Risk of Temporomandibular Pain

When measured once, psychological stress predicts development of painful temporomandibular disorder (TMD). However, a single measurement fails to characterize the dynamic nature of stress over time. Moreover, effects of stress on pain likely vary according to biological susceptibility. We hypothesized that temporal escalation in stress exacerbates risk for TMD, and the effect is amplified by allelic variants in a gene, catechol-O-methyltransferase (COMT), regulating catechol neurotransmitter catabolism. We used data from the Orofacial Pain: Prospective Evaluation and Risk Assessment prospective cohort study of 2,707 community-dwelling adults with no lifetime history of TMD on enrollment. At baseline and quarterly periods thereafter, the Perceived Stress Scale (PSS) measured psychological stress. Genotyped DNA from blood samples determined COMT diplotypes. During follow-up of 0.25 to 5.2 y, 248 adults developed examiner-verified incident TMD. PSS scores at baseline were 20% greater (P < 0.001) in adults who developed incident TMD compared with TMD-free controls. Baseline PSS scores increased by 9% (P = 0.003) during follow-up in cases but remained stable in controls. This stress escalation was limited to incident cases with COMT diplotypes coding for low-activity COMT, signifying impaired catabolism of catecholamines. Cox regression models confirmed significant effects on TMD hazard of both baseline PSS (P < 0.001), modeled as a time-constant covariate, and change in PSS (P < 0.001), modeled as a time-varying covariate. Furthermore, a significant (P = 0.04) interaction of COMT diplotype and time-varying stress showed that a postbaseline increase of 1.0 standard deviation in PSS more than doubled risk of TMD incidence in subjects with low-activity COMT diplotypes (hazard ratio = 2.35; 95% confidence limits: 1.66, 3.32), an effect not found in subjects with high-activity COMT diplotypes (hazard ratio = 1.42; 95% confidence limits: 0.96, 2.09). Findings provide novel insights into dynamic effects of psychological stress on TMD pain, highlighting that effects are most pronounced in individuals whose genetic susceptibility increases responsiveness to catecholamine neurotransmitters.

Hemispheric cortical dysplasia secondary to a mosaic somatic mutation in MTOR

OBJECTIVE

To define causative somatic mutations in resected brain tissue from an infant with intractable epilepsy secondary to hemispheric cortical dysplasia.

METHODS

Whole-exome sequencing was conducted on genomic DNA derived from both resected brain tissue and peripheral blood leukocytes. Comparison of the brain vs blood sequencing results was performed using bioinformatic methods designed to detect low-frequency genetic variation between tissue pairs.

RESULTS

Histopathology of the resected tissue showed dyslamination and dysmorphic neurons, but no balloon cells, consistent with focal cortical dysplasia type IIa. mTOR activation was observed by immunohistochemistry in the dysplasia. A missense mutation (c.4487T>G; p.W1456G) was detected in the FAT domain of MTOR in DNA from the dysplasia but not in lymphocytes. The mutation is predicted damaging (i.e., leading to mTOR activation) and was observed as a low-level mosaic with 8% of cells being heterozygous for the variant.

CONCLUSIONS

We report the novel finding of an MTOR mutation associated with nonsyndromic cortical dysplasia. Somatic-specific mutations in MTOR and related genes should be considered in a broader spectrum of patients with hemispheric malformations and more restricted forms of cortical dysplasia.

Familial cortical dysplasia type IIA caused by a germline mutation in DEPDC5

Whole-exome sequencing of two brothers with drug-resistant, early-onset, focal epilepsy secondary to extensive type IIA focal cortical dysplasia identified a paternally inherited, nonsense variant of DEPDC5 (c.C1663T, p.Arg555*). This variant has previously been reported to cause familial focal epilepsy with variable foci in patients with normal brain imaging. Immunostaining of resected brain tissue from both brothers demonstrated mammalian target of rapamycin (mTOR) activation. This report shows the histopathological features of cortical dysplasia associated with a DEPDC5 mutation, confirms mTOR dysregulation in the malformed tissue and expands the spectrum of neurological manifestations of DEPDC5 mutations to include severe phenotypes with large areas of cortical malformation.

Pediatric dural arteriovenous malformations

Pediatric dural arteriovenous malformations (dAVMs) are rare lesions that have a high mortality rate and require complex management. The authors report 3 cases of pediatric dAVMs that presented with macrocrania and extracranial venous distension. Dural sinus thrombosis developed in 2 of the cases prior to any intervention, which is an unusual occurrence for this particular disease. All 3 cases were treated using staged endovascular embolization with a favorable outcome in 1 case and a poor outcome in the other 2 cases. Complications developed in all cases and included dural sinus thrombosis, parenchymal hemorrhage, intracranial venous hypertension, and seizures. The strategies and challenges used in managing these patients will be presented and discussed, along with a review of the literature. While outcomes remain poor, the authors conclude that prompt treatment with endovascular embolization provides the best results for children with these lesions. A well-established venous collateral circulation draining directly to the internal jugular veins may further improve the rate of favorable outcome after embolization.

Sleep apnea symptoms and risk of temporomandibular disorder: OPPERA cohort

The authors tested the hypothesis that obstructive sleep apnea (OSA) signs/symptoms are associated with the occurrence of temporomandibular disorder (TMD), using the OPPERA prospective cohort study of adults aged 18 to 44 years at enrollment (n = 2,604) and the OPPERA case-control study of chronic TMD (n = 1,716). In both the OPPERA cohort and case-control studies, TMD was examiner determined according to established research diagnostic criteria. People were considered to have high likelihood of OSA if they reported a history of sleep apnea or ≥ 2 hallmarks of OSA: loud snoring, daytime sleepiness, witnessed apnea, and hypertension. Cox proportional hazards regression estimated hazard ratios (HRs) and 95% confidence limits (CL) for first-onset TMD. Logistic regression estimated odds ratios (OR) and 95% CL for chronic TMD. In the cohort, 248 individuals developed first-onset TMD during the median 2.8-year follow-up. High likelihood of OSA was associated with greater incidence of first-onset TMD (adjusted HR = 1.73; 95% CL, 1.14, 2.62). In the case-control study, high likelihood of OSA was associated with higher odds of chronic TMD (adjusted OR = 3.63; 95% CL, 2.03, 6.52). Both studies supported a significant association of OSA symptoms and TMD, with prospective cohort evidence finding that OSA symptoms preceded first-onset TMD.

Intrinsic epileptogenicity of cortical tubers revealed by intracranial EEG monitoring

OBJECTIVE

We sought to identify intracranial EEG patterns characteristic of epileptogenic tubers and to understand the contribution of perituberal cortex.

METHODS

Twenty-three intracranial EEG monitoring studies were reviewed from 17 children aged 1.3-7.7 years with tuberous sclerosis complex and intractable multifocal epilepsy, 14 with a history of epileptic spasms. Interictal epileptiform discharges and ictal rhythms for 60 electroclinically distinct seizures (EDS) were analyzed in relation to 162 sampled tubers.

RESULTS

Localized, tuber-related, ictal rhythms were seen in 49/60 EDS, most commonly as low-voltage fast activity recruiting to rhythmic spiking, then diffuse slowing or bursts of ripple range activity. Ictal onset in localized EDS involved only tubers in 57% and tubers with perituberal cortex in 31%. Ictal fast ripples (FR) noted at seizure onset in 15/38 localized EDS were confined to tubers in 73% and involved tuber with perituberal cortex in 27%. Intraictal activation occurred during seizure propagation in 19 localized EDS, being to tubers in 63% and to tubers with perituberal cortex in 37%; 63% of activated tubers generated independent EDS. Trains of periodic sharp waves on an attenuated background were seen interictally at 36/162 tubers, with 67% of those tubers generating EDS (p = 0.0001). Interictal FR, when present, involved tubers more commonly than perituberal cortex but were not associated with EDS.

CONCLUSION

The study demonstrates interictal and ictal intracranial EEG findings characteristic of epileptogenic tubers, suggests that tubers play a greater role in seizure genesis than perituberal cortex, and suggests tuberectomy may be a sufficient surgical approach in a number of patients.

Janus molecule I: dichotomous effects of COMT in neuropathic vs nociceptive pain modalities

The enzyme catechol-O-methyltransferase (COMT) has been shown to play a critical role in pain perception by regulating levels of epinephrine (Epi) and norepinephrine (NE). Although the key contribution of catecholamines to the perception of pain has been recognized for a long time, there is a clear dichotomy of observations. More than a century of research has demonstrated that increasing adrenergic transmission in the spinal cord decreases pain sensitivity in animals. Equally abundant evidence demonstrates the opposite effect of adrenergic signaling in the peripheral nervous system, where adrenergic signaling increases pain sensitivity. Viewing pain processing within spinal and peripheral compartments and determining the directionality of adrenergic signaling helps clarify the seemingly contradictory findings of the pain modulatory properties of adrenergic receptor agonists and antagonists presented in other reviews. Available evidence suggests that adrenergic signaling contributes to pain phenotypes through α(1/2) and β(2/3) receptors. While stimulation of α(2) adrenergic receptors seems to uniformly produce analgesia, stimulation of α(1) or β receptors produces either analgesic or hyperalgesic effects. Establishing the directionality of adrenergic receptor modulation of pain processing, and related COMT activity in different pain models are needed to bring meaning to recent human molecular genetic findings. This will enable the translation of current findings into meaningful clinical applications such as diagnostic markers and novel therapeutic targets for complex human pain conditions.

Functional properties of tooth pulp neurons responding to thermal stimulation

The response properties of tooth pulp neurons that respond to noxious thermal stimulation of the dental pulp have been not well-studied. The present study was designed to characterize the response properties of tooth pulp neurons to noxious thermal stimulation of the dental pulp. Experiments were conducted on 25 male ferrets, and heat stimulation was applied by a computer-controlled thermode. Only 15% of tooth pulp neurons (n = 39) responded to noxious thermal stimulation of the teeth. Tooth pulp neurons were found in both the superficial and deep nuclear regions of the subnucleus caudalis (Vc) and in the interface between the nucleus caudalis and interpolaris (Vc/Vi). Thirty-seven neurons had cutaneous receptive fields and were classified as either NS (16) or WDR (21) neurons. Repeated heat stimulation of the dental pulp sensitized and increased the number of electrically evoked potentials of tooth pulp neurons. These results provide evidence that both the Vc and Vc/Vi regions contain neurons that respond to noxious thermal stimulation of the dental pulp, and that these cells may contribute to the sensitization process associated with symptomatic pulpitis.

Temporoparietooccipital disconnection in children with intractable epilepsy

OBJECT

Temporoparietooccipital (TPO) disconnection is described mainly in children with diffuse posterior quadrant lesions and concordant electroencephalography (EEG) findings. The authors report on 16 children who underwent TPO surgery, including 4 with no definite epileptogenic lesion and 8 with generalized electroclinical manifestations.

METHODS

The authors conducted a retrospective review of clinical, neuropsychological, EEG, imaging, and histopathological data in 16 children with intractable epilepsy who underwent TPO disconnection and/or resection at their center between December 1998 and March 2010.

RESULTS

Seizure onset occurred between the ages of 1 and 24 months, and TPO surgery was performed between the ages of 0.2 and 17 years. All children had refractory seizures, including epileptic spasms in 10 and tonic seizures in 7, and all had developmental delay. Twelve children had epileptogenic lesions on MR imaging, including 6 with posterior quadrant dysplasia. Four children had only subtle white matter signal change or unusual sulcation on MR imaging, associated with subtle but concordant EEG and functional imaging abnormalities. After a mean follow-up of 52 months (range 12-114 months), 9 children (56%) are seizure-free and 5 (31%) experienced seizure reduction of greater than 50%. Focal or regional background slowing on EEG was correlated with favorable seizure outcome. Five children showed developmental progress and 3 had acceleration in development following surgery. None of the children developed new motor deficits postoperatively.

CONCLUSIONS

Temporoparietooccipital disconnection is an effective, motor-sparing epilepsy surgery procedure for selected children with refractory focal or generalized seizures with localization to the posterior quadrant on 1 side, with or without a discrete lesion on MR imaging.

The potential of capillary birthmarks as a significant marker for capillary malformation-arteriovenous malformation syndrome in children who had nontraumatic cerebral hemorrhage

BACKGROUND/PURPOSE

Capillary malformation-arteriovenous malformation (CM-AVM) is a new autosomal dominant disorder with cutaneous capillary malformations (CM) and high-flow cerebral arteriovenous malformations (AVM). Patients may have Parkes-Weber syndrome. This study determined if cutaneous CM are a significant indicator of CM-AVM in children with cerebral bleeds.

METHODS

Children with cerebral AVMs between 1991 and 2009 were reviewed. A family history of brain hemorrhage, AVMs, or cutaneous birthmarks was elicited. Patients and siblings were examined for CM and a family tree recorded. A brief questionnaire determined the family's opinion regarding screening for this syndrome.

RESULTS

Of 30 families, 1 family had Parkes-Weber syndrome. In 3 families, both patient and relatives had CM. In 9 families, patients had no CM, but relatives had them. One family had hereditary hemorrhagic telangiectasia. From the survey, 80% of families would be concerned about vascular marks, and 87% of families would allow screening for cerebral AVMs.

CONCLUSION

A family history of vascular marks may predict families at risk of having a cerebral AVM with hemorrhage. Most families would agree to screening. However, family history and physical examination alone do not confirm CM-AVM but form a useful screening tool to identify families needing further investigations with genetic testing and/or magnetic resonance imaging.

Pituitary function in paediatric survivors of severe traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI)-mediated hypopituitarism is an increasingly recognised problem. Paediatric survivors of TBI may be vulnerable to the possible effects of pituitary deficits as pituitary hormones control normal growth and development. Research concerning pituitary dysfunction following childhood TBI is limited.

AIM

To identify pituitary dysfunction in paediatric survivors of severe TBI.

METHODS

Of 1020 children who sustained a TBI and were admitted to the Royal Children's Hospital, Melbourne, Australia over 10 years, 117 were identified as survivors of severe TBI. 54 patients (31 males) were enrolled and administered questionnaires regarding quality of life and possible endocrine dysfunction. Where indicated, hormone testing was performed.

RESULTS

29 of the 54 patients underwent hormonal investigations, while 21 who had satisfactory questionnaires did not (four patients had already been diagnosed with pituitary deficiencies). In those 29 patients, TBI occurred at ages ranging from 0.25 to 16.80 years (median 9.7 years). Time from TBI to study ranged from 0.9 to 8.5 years (median 4.5 years). Of the 54 patients, nine had pituitary dysfunction, of whom four had multiple pituitary hormone deficiencies.

CONCLUSIONS

Our study that confirms that paediatric survivors of severe TBI may develop pituitary dysfunction. Pituitary function should therefore be determined in these patients.

Multiple factors contribute to neuropsychological outcome in children with posterior fossa tumors

Cognitive deficits are frequently reported in children treated for posterior fossa (PF) tumors. A range of tumor, treatment, medical and treatment complications have been implicated in causing a variety of cognitive deficits. The aim of this study is to identify factors that influence intelligence, attention and information processing in these children. Thirty-five children (aged 4-16) with PF tumors attending the Royal Children's Hospital Melbourne, Australia, were enrolled into a prospective, repeated measures design. Neuropsychological assessments were conducted at diagnosis and at 12 month intervals for three years. The results find that the PF tumor, hydrocephalus, white matter injury and radiation therapy have various impacts on intelligence, attention and information processing skills, and contribute to the long term outcome in children treated for PF tumor. The neurological structures that subserve the efficient function of attention and information processing are particularly vulnerable to those factors.

Influence of psychological factors on risk of temporomandibular disorders

Psychological characteristics potentially may be a cause or consequence of temporomandibular disorder (TMD). We hypothesized that psychological characteristics associated with pain sensitivity would influence risk of first-onset TMD, but the effect could be attributed to variation in the gene encoding catechol-O-methyltransferase (COMT). We undertook a prospective cohort study of healthy female volunteers aged 18-34 yrs. At baseline, participants were genotyped, they completed psychological questionnaires, and underwent quantitative sensory testing to determine pain sensitivity. We followed 171 participants for up to three years, and 8.8% of them were diagnosed with first-onset TMD. Depression, perceived stress, and mood were associated with pain sensitivity and were predictive of 2- to 3-fold increases in risk of TMD (P < 0.05). However, the magnitude of increased TMD risk due to psychological factors remained unchanged after adjustment for the COMT haplotype. Psychological factors linked to pain sensitivity influenced TMD risk independently of the effects of the COMT haplotype on TMD risk.

Dysembryoplastic neuroepithelial tumor (DNT)-like oligodendrogliomas or DNTs evolving into oligodendrogliomas: Two illustrative cases

A review of dysembryoplastic neuroepithelial tumors (DNTs) in 14 patients over a 12-year period revealed four patients re-operated because of changes on magnetic resonance imaging (MRI) suggesting tumor recurrence or progression. In three of these, the histological features were identical to the initial DNT. In the fourth patient, persistent DNT was surrounded by WHO grade 2 oligoastrocytoma. In one of the other 10 patients, WHO grade 2 oligodendroglioma was present in white matter deep to and completely separate from a cortically based DNT. Fluorescence in situ hybridization showed codeletion of 1p and 19q in both the DNT and oligodendroglioma and oligoastrocytoma components. Deletions were not identified in any other tumor. Our findings corroborate other studies that 1p and 19q deletions are uncommon in DNT. These two unusual tumors also raise the possibility that rare DNTs may evolve into oligodendroglioma or oligoastrocytoma. DNTs with this altered biology can be identified by 1p and 19q deletion analysis.

Development of a pilocytic astrocytoma in a dysembryoplastic neuroepithelial tumor. Case report

Dysembryoplastic neuroepithelial tumors (DNETs) are benign supratentorial tumors based in the cerebral cortex. They usually are found in children and young adults with seizures that tend to become refractory to medical treatment. In the vast majority of cases resection results in good seizure control, and adjuvant therapy is not required. When tumors thought to be DNETs are not resected due to their proximity to eloquent cortex, lack of change in the clinical and neuroimaging features over time supports the diagnosis of DNET. The authors report on a patient in whom a pilocytic astrocytoma developed within a DNET, raising questions regarding the classification of these lesions and the need for lifelong clinical and imaging surveillance. This paper adds to the growing body of literature about the biological behavior of these lesions.

Human catechol-O-methyltransferase haplotypes modulate protein expression by altering mRNA secondary structure

Catechol-O-methyltransferase (COMT) is a key regulator of pain perception, cognitive function, and affective mood. Three common haplotypes of the human COMT gene, divergent in two synonymous and one nonsynonymous position, code for differences in COMT enzymatic activity and are associated with pain sensitivity. Haplotypes divergent in synonymous changes exhibited the largest difference in COMT enzymatic activity, due to a reduced amount of translated protein. The major COMT haplotypes varied with respect to messenger RNA local stem-loop structures, such that the most stable structure was associated with the lowest protein levels and enzymatic activity. Site-directed mutagenesis that eliminated the stable structure restored the amount of translated protein. These data highlight the functional significance of synonymous variations and suggest the importance of haplotypes over single-nucleotide polymorphisms for analysis of genetic variations.

Mucocele of the sphenoid sinus

The sphenoid sinus is the least common site of mucocele of all paranasal sinuses. It is very rare in children, especially in those younger than 12 years when pneumatization of the sphenoid sinus is completed. We report a case of histologically proven sphenoidal mucocele in a 5-year-old child. The child presented with an acute onset of significant visual impairment and headache. His vision gradually improved after trans-nasal sphenoidotomy and drainage of the sinus content with return of complete normal baseline vision after 2 months.

Hypothalamic hamartomas--clinical, neuropathological and surgical aspects

INTRODUCTION

Hypothalamic hamartomas are rare congenital lesions of the tuber cinereum presenting with the classic triad of gelastic epilepsy, central precocious puberty and developmental delay. The clinical course in the majority is one of progression, commencing with gelastic seizures in infancy, deteriorating into more complex seizure disorders and resulting in a catastrophic epilepsy associated with a concomitant cognitive and behavioural decline.

OBSERVATION

Electrophysiological, radiological and pathophysiological studies have confirmed the intrinsic epileptogenicity of the hypothalamic hamartoma. Secondary generalised epilepsy seen in this condition is theorised to be through propagation via the mamillothalamic pathways with attachment to the mamillary bodies identified on MRI. Indications as to timing for surgery remain ill-defined although there is a theoretical argument to intervene before the development of secondary generalised epilepsy.

SURGICAL APPROACH

Currently, the most effective surgical route appears to be the transcallosal anterior interforniceal approach although newer approaches of endoscopic disconnection and radiosurgery are being assessed.

Intelligence and adaptive function in children diagnosed with brain tumour during infancy

BACKGROUND

Late effects of treatment in children diagnosed and treated for brain tumours in infancy is a major concern. Assessment of infants presenting with brain tumours is difficult and there is little information available regarding the development of infants prior to treatment and hence the impact of the tumour itself on developmental outcomes.

AIM

To describe the development of children diagnosed with brain tumours in infancy and to document their cognitive and adaptive function at school entry.

METHOD

Infants were psychologically evaluated at the time of diagnosis of a brain tumour and during their fifth or sixth year in preparation for school entry.

RESULTS

Children diagnosed with brain tumours in infancy display developmental delays in a number of areas of adaptive function. By the time these children are school age they display further compromise in cognitive and academic skills and adaptive behaviour. Higher levels of deficit at follow-up were associated with tumour location in the supratentorium, younger age at diagnosis and longer time since diagnosis. The effect of radiotherapy could not be determined because of differing degrees of developmental compromise in the treatment groups at baseline.

CONCLUSION

Brain tumours in infancy confer a risk of poor developmental progress at the time of diagnosis. These children display additional compromise of development by the time they reach school age. Research protocols evaluating the impact of treatment in infants diagnosed with brain tumours need to take account of the developmental status of the child at diagnosis.

Enlarged parietal foramina: MR imaging features in the fetus and neonate

Enlarged parietal foramina are believed to be benign and familial and due to a variable degree of defective intramembranous ossification of the parietal bones. We report 2 patients with this condition in whom fetal and neonatal MR imaging studies illustrate the antenatal and perinatal evolution of this condition and the associated persistence of a falcine sinus. We discuss its relationship to the spectrum of cephalocoeles.

Health related quality of life and psychological outcome in patients treated for craniopharyngioma in childhood

Patients with craniopharyngioma are at risk for many adverse effects related to the tumour's invasive behaviour and its proximity to many vital structures. Profound psychosocial problems, memory impairment, pituitary and hypothalamic dysfunction in addition to the physical handicap of visual loss are frequently recognized sequelae of craniopharyngioma treatment.

OBJECTIVES

To examine health related quality of life (QoL) and psychological outcomes of patients treated for craniopharyngioma at the Royal Children's Hospital, Melbourne, between January 1980 and September 2003.

PATIENTS

Seven (17.4%) of 46 (26 male) had died. Thirty-nine remained, of whom 30 were contactable. Eighteen of 30 (8 male), mean age 21.2 +/- 6.7 years, agreed to evaluation, of whom 16/18 (88.9%) had three or more pituitary hormone deficiencies, 11/18 had visual impairment and 9/18 obesity.

MEASUREMENTS

The Adult GH-Deficient Assessment (AGHDA) and Psychological General Well-Being (PGWB) questionnaires were employed to assess quality of life in patients and age- and sex-matched healthy controls. Additional psychological assessment, including intellectual and academic skills, emotional function, and adaptive behaviour, had been undertaken in 12 patients at a previous time.

RESULTS

High levels of physical morbidity and psychological disability were described. The General Health score of patients was significantly worse than for controls on PGWB (p = 0.025), anxiety was higher in those who had surgery alone (p = 0.008) and subjective QoL associated with GHD using AGHDA was lower (p = 0.006). Few craniopharyngioma survivors (18/30) were available for evaluation, demonstrating difficulties in attempts to assess this complex group. The discrepancy between results of objective and subjective measures of QoL is discussed in terms of adaptation to illness, disabilities and changed perception of life fulfilment.

CONCLUSIONS

Craniopharyngioma and its treatment result in significant, complex medical, social, psychological and emotional difficulties. The degree of global disability is not reflected in subjective QoL reports for this group, highlighting the need for careful selection of assessment instruments.

Diffuse choroid plexus hyperplasia: an under-diagnosed cause of hydrocephalus in children?

Hydrocephalus is a common neurological disorder in children and the result of a variety of causes. However, with the advancement of imaging modalities, particularly MRI, previously reported rarer causes of hydrocephalus in children are now being more readily appreciated. We report an 11-year-old boy with diffuse villous hyperplasia of the choroid plexus. He had a ventriculo-peritoneal (VP) shunt in-situ and a prior diagnosis from infancy of congenital aqueduct stenosis as the cause of his hydrocephalus. His current presentation was with further shunt dysfunction. CT and MRI demonstrated enlarged choroid plexuses but did not confirm aqueduct stenosis. CSF overproduction was demonstrated from the externalized ventricular drain. The enlarged choroid plexuses were surgically resected and histology confirmed choroid plexus hyperplasia. Identification of choroid plexus hyperplasia is important since the neurosurgical management of hydrocephalus is not VP shunt insertion, but resection of the hyperplastic choroid plexus.

Results of a phase 1 study utilizing monocyte-derived dendritic cells pulsed with tumor RNA in children and young adults with brain cancer

We conducted a phase 1 study of 9 pediatric patients with recurrent brain tumors using monocyte-derived dendritic cells pulsed with tumor RNA to produce antitumor vaccine (DCRNA) preparations. The objectives of this study included (1) establishing safety and feasibility and (2) measuring changes in general, antigen-specific, and tumor-specific immune responses after DCRNA. Dendritic cells were derived from freshly isolated monocytes after 7 days of culture with IL-4 and granulocyte-macrophage colony-stimulating factor, pulsed with autologous tumor RNA, and then cryopreserved. Patients received at least 3 vaccines, each consisting of an intravenous and an intradermal administration at biweekly intervals. The study showed that this method for producing and administering DCRNA from a single leukapheresis product was both feasible and safe in this pediatric brain tumor population. Immune function at the time of enrollment into the study was impaired in all patients tested. While humoral responses to recall antigens (diphtheria and tetanus) were intact in all patients, cellular responses to mitogen and recall antigens were below normal. Following DCRNA vaccine, 2 of 7 patients showed stable clinical disease and 1 of 7 showed a partial response. Two of 7 patients who were tested showed a tumor-specific immune response to DCRNA. This study showed that DCRNA vaccines are both safe and feasible in children with tumors of the central nervous system with a single leukapheresis.

Long-lasting inflammation and long-term hyperalgesia after subcutaneous formalin injection into the rat hindpaw

Subcutaneous formalin injection is widely used as a nociceptive stimulus in the rat. This procedure evokes overt behaviors that last about 90 minutes. However, little is known about the duration of paw inflammation and alterations in pain sensitivity to noxious stimuli after 2 hours. We studied the nociceptive responses to thermal and mechanical stimuli 2 hours to 4 weeks after formalin injection into the dorsal or plantar side of the hindpaw. Thirty-two adult male Sprague-Dawley rats were divided into 3 groups: In group I, 50 microL of 5% formalin was injected into the plantar side (n = 12); in group II, 50 microL of 5% formalin was injected into the dorsal side (n = 12); in group III, 50 microL saline was injected into the dorsal or plantar side of the hindpaw (n = 8). Nociceptive responses to thermal and mechanical stimuli applied to the dorsal or plantar surfaces of the injected and the contralateral hindpaws were recorded. The injection of formalin into the rat's hindpaw produced a hypoalgesic region around the injection site. In contrast, hyperalgesic responses to thermal and mechanical stimulation were induced on the opposite surface of the injected hindpaw as well as in the contralateral noninjected hindpaw. The hyperalgesic responses, which were observed 2 hours after formalin administration, were enhanced 1 to 3 days after injection and lasted 3 to 4 weeks. These results suggest that peripheral inflammation after subcutaneous formalin injection produces a long-lasting sensitization. Possible mechanisms for these changes in nociception are discussed.

Increased perception of post-ischemic paresthesias in depressed subjects

A psychophysical assessment of sensory activity linked to unmyelinated and myelinated primary afferents was conducted by estimating the intensity of thermal and tactile post-ischemic paresthesias in 11 nontreated depressed subjects (Zung's index > or =50) and 19 controls. Blood flow in the dominant forearm was arrested until ischemic pain tolerance was reached. Ischemic pain and post-ischemic paresthesias were numerically rated. The duration of blood flow occlusion to the time of ischemic pain tolerance was similar in both groups. Thermal (warm/cool) and tactile (tingling) paresthesias were 96% and 57% more intense in depressed than in control subjects, respectively. Zung's depression scores were positively correlated with the tingling and thermal paresthesias. Ischemic pain intensity correlated positively with thermal paresthesias. These findings suggest that depression is associated with enhanced sensory paresthesias that are known to be predominately linked to unmyelinated afferent activity.

The effects of noxious dental heating on the jaw-opening reflex and trigeminal Fos expression in the ferret

Previous studies have established that the activation of peripheral nociceptors alters the central processing of nociceptive stimuli. In this study, we examined whether noxious heating of the dental pulp enhances the nociceptive jaw-opening reflex (JOR) and the expression of the immediate early gene c-fos in chloral hydrate/pentobarbital-anesthetized ferrets. We hypothesized that the application of noxious heat to the dental pulp, a procedure that evokes a preferential activation of pulpal C-fibers, will enhance JOR responses to electrical stimulation of the tooth pulp and that this enhanced response will be associated with the expression of Fos protein in discrete regions of the trigeminal nucleus. Consistent with our predictions, we observed that noxious heat conditioning enhanced the JOR as indicated by an increase in the magnitude of the signal averaged digastric electromyogram response evoked by electrical stimuli applied to either a heat-conditioned maxillary canine or the contralateral nonconditioned canine. The enhancement in JOR responses was independent of temporal summation of the electrical stimulus for test stimuli delivered at either 1.0 or 0.1 Hz. Sensitization of the JOR was associated with an increase in the number of immunohistochemically identified Fos-positive nuclei in trigeminal caudalis (Vc) and the transition zone between trigeminal interpolaris and caudalis (Vi/Vc) ipsilateral to the site of stimulation compared with sham stimulated animals. These findings suggest that neuronal populations in Vc and Vi/Vc play a role in the enhanced reflex responses to tooth pulp stimulation and may contribute to the pain and hyperalgesia associated with a symptomatic pulpitis.

Sex differences in chest pain in patients with documented coronary artery disease and exercise-induced ischemia: Results from the PIMI study

BACKGROUND

Sex differences in the pathophysiologic course of coronary artery disease (CAD) are widely recognized, yet accurate diagnosis of coronary artery disease in women remains challenging.

METHODS

To determine sex differences in the clinical manifestation of CAD, we studied chest pain reported during daily activities, exercise, and mental stress in 170 men and 26 women. All patients had documented CAD (>50% narrowing in at least 1 major coronary artery or prior myocardial infarction) and all had 1-mm ST-segment depression on treadmill exercise. We collected psychologic test results, serum samples (potassium, epinephrine, norepinephrine, cortisol, b-endorphin, and glucose), and cardiac function, sensory threshold, and autonomic function data at specified times before, during, or after exercise and mental stress tests to assess measures of depression, anxiety, and neurohormonal and thermal pain perception.

RESULTS

Women reported chest pain more often than men during daily activities (P =.04) and during laboratory mental stressors (P =.01) but not during exercise. Men had lower scores than women on measures of depression, trait anxiety, harm avoidance, and reward dependence (P <.05 for all). Women had significantly lower plasma b-endorphin levels at rest (4.2 +/- 3.9 vs 5.0 +/- 2.5 pmol/L for men, P =.005) and at maximal mental stress (6.4 +/- 5.1 vs 7.4 +/- 3.5 pmol/L for men, P <.01). A higher proportion of women than men had marked pain sensitivity to graded heat stimuli applied to skin (hot pain threshold <41 degrees C, 33% vs 10%, P =.001).

CONCLUSIONS

Our results reflect sex differences in the affective and discriminative aspects of pain perception and may help explain sex-related differences in clinical presentations.

Estrous cycle modulation of nociceptive behaviors elicited by electrical stimulation and formalin

The impact of circulating ovarian hormones on nociceptive behaviors elicited by phasic and tonic stimuli was evaluated in rats using two behavioral tests: an operant escape task and the formalin test. The operant escape task was structured to separately evaluate hindlimb flexion reflexes, the latency of escape, and the amplitude of peak vocalization to a series of phasic electrocutaneous stimuli (0.05-0.8 mA), whereas the formalin test evaluated nociceptive behaviors elicited by tonic stimulation following a subcutaneous injection of dilute formalin (1%). Hindlimb reflex amplitude, escape latency, and peak vocalization varied across the estrous cycle, such that rats were most sensitive to electrical stimuli during proestrus (reflex and escape latency) and diestrus (vocalization). Furthermore, morphine-induced (3 mg/kg sc) attenuation of hindlimb reflex amplitude was sensitive to estrous cycling. During proestrus, morphine produced less attenuation of hindlimb reflex amplitude than during nonproestrus phases. However, estrous cycling did not alter nociceptive behaviors elicited by 1% formalin. These data support the notion that circulating ovarian hormones may differentially modulate behaviors associated with phasic and tonic pain.

Effects of systemic morphine on escape latency and a hindlimb reflex response in the rat

The present study uses focal electrical stimulation of myelinated nociceptors to simultaneously assess behavioral responses that are organized at spinal and supraspinal sites in the rat. Hindlimb reflex amplitude and the latency to operant escape responses by a forelimb were recorded for each stimulus presentation to a hindlimb across a wide range of intensities. This paradigm provided a tool whereby effects of morphine on conscious escape responses could be delineated from effects on a segmental flexion reflex over a range of doses. Administration of morphine (3 mg/kg and 10 mg/kg, subcutaneously) increased the latency of escape responses and decreased the amplitude of reflex responses in a dose-dependent manner. However, morphine produced a greater suppression of reflex responses compared with the increase in effects on escape latencies. The effects of morphine on escape latency were not expressed at the highest stimulus intensities (0.6 to 0.8 mA), whereas reflex responses were attenuated at all suprathreshold stimulus intensities. Thus, electrically evoked, spinal-mediated responses of rats are not affected by morphine in the same manner as electrically evoked supraspinal-mediated nociceptive behaviors. However, both measures confirm evidence that responses elicited by activation of myelinated afferents are less powerfully affected by morphine than responses to input from unmyelinated nociceptors.