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Concept: Arnold-Chiari malformation

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We describe the case of a 29-year-old parturient who, after undergoing elective cesarean delivery, displayed symptoms of lower extremity weakness and sensory deficit. Her past medical history was significant for asymptomatic Arnold Chiari Type I malformation and asthma. She had received spinal anesthesia that failed to achieve an adequate surgical level requiring conversion to general anesthesia. After tracheal extubation, she exhibited bilateral leg weakness that did not resolve over the next 4-6h. An urgent magnetic resonance imaging scan revealed a normal spine with no evidence of hematoma. The lower extremity paresis persisted and a neurologist diagnosed psychogenic paresis, a type of conversion disorder. Interestingly, the patient’s postoperative leg paresis was not her first occurrence of neurological dysfunction after dural puncture. At 27weeks of gestation, she had similar lower extremity symptoms after a lumbar puncture, performed to exclude meningitis for severe headache symptoms. Psychogenic paresis is not commonly reported in the medical literature and we found no reports of psychogenic paresis after spinal anesthesia in a parturient or recurrent psychogenic paresis. We review the various risk factors, etiology, neurological signs and symptoms, types, therapy and future management of a patient with recurrent conversion disorder.

Concepts: Medicine, Childbirth, The Canon of Medicine, Neurology, Anesthesia, Epidural, Caesarean section, Arnold-Chiari malformation

165

Chiari Type I Malformation (CMI) is characterized by displacement of the cerebellar tonsils below the base of the skull, resulting in significant neurologic morbidity. Although multiple lines of evidence support a genetic contribution to disease, no genes have been identified. We therefore conducted the largest whole genome linkage screen to date using 367 individuals from 66 families with at least two individuals presenting with nonsyndromic CMI with or without syringomyelia. Initial findings across all 66 families showed minimal evidence for linkage due to suspected genetic heterogeneity. In order to improve power to localize susceptibility genes, stratified linkage analyses were performed using clinical criteria to differentiate families based on etiologic factors. Families were stratified on the presence or absence of clinical features associated with connective tissue disorders (CTDs) since CMI and CTDs frequently co-occur and it has been proposed that CMI patients with CTDs represent a distinct class of patients with a different underlying disease mechanism. Stratified linkage analyses resulted in a marked increase in evidence of linkage to multiple genomic regions consistent with reduced genetic heterogeneity. Of particular interest were two regions (Chr8, Max LOD = 3.04; Chr12, Max LOD = 2.09) identified within the subset of “CTD-negative” families, both of which harbor growth differentiation factors (GDF6, GDF3) implicated in the development of Klippel-Feil syndrome (KFS). Interestingly, roughly 3-5% of CMI patients are diagnosed with KFS. In order to investigate the possibility that CMI and KFS are allelic, GDF3 and GDF6 were sequenced leading to the identification of a previously known KFS missense mutation and potential regulatory variants in GDF6. This study has demonstrated the value of reducing genetic heterogeneity by clinical stratification implicating several convincing biological candidates and further supporting the hypothesis that multiple, distinct mechanisms are responsible for CMI.

Concepts: DNA, Gene, Genetics, Mutation, Biology, Genome, Genetic linkage, Arnold-Chiari malformation

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Postural tachycardia syndrome (POTS) is defined by a heart rate increment of 30 beats/min or more within 10 minutes of standing or head-up tilt in the absence of orthostatic hypotension; the standing heart rate is often 120 beats/min or higher. POTS manifests with symptoms of cerebral hypoperfusion and excessive sympathoexcitation. The pathophysiology of POTS is heterogeneous and includes impaired sympathetically mediated vasoconstriction, excessive sympathetic drive, volume dysregulation, and deconditioning. POTS is frequently included in the differential diagnosis of chronic unexplained symptoms, such as inappropriate sinus tachycardia, chronic fatigue, chronic dizziness, or unexplained spells in otherwise healthy young individuals. Many patients with POTS also report symptoms not attributable to orthostatic intolerance, including those of functional gastrointestinal or bladder disorders, chronic headache, fibromyalgia, and sleep disturbances. In many of these cases, cognitive and behavioral factors, somatic hypervigilance associated with anxiety, depression, and behavioral amplification contribute to symptom chronicity. The aims of evaluation in patients with POTS are to exclude cardiac causes of inappropriate tachycardia; elucidate, if possible, the most likely pathophysiologic basis of postural intolerance; assess for the presence of treatable autonomic neuropathies; exclude endocrine causes of a hyperadrenergic state; evaluate for cardiovascular deconditioning; and determine the contribution of emotional and behavioral factors to the patient’s symptoms. Management of POTS includes avoidance of precipitating factors, volume expansion, physical countermaneuvers, exercise training, pharmacotherapy (fludrocortisone, midodrine, β-blockers, and/or pyridostigmine), and behavioral-cognitive therapy. A literature search of PubMed for articles published from January 1, 1990, to June 15, 2012, was performed using the following terms (or combination of terms): POTS; postural tachycardia syndrome, orthostatic; orthostatic; syncope; sympathetic; baroreceptors; vestibulosympathetic; hypovolemia; visceral pain; chronic fatigue; deconditioning; headache; Chiari malformation; Ehlers-Danlos; emotion; amygdala; insula; anterior cingulate; periaqueductal gray; fludrocortisone; midodrine; propranolol; β-adrenergic; and pyridostigmine. Studies were limited to those published in English. Other articles were identified from bibliographies of the retrieved articles.

Concepts: Hypertension, Cardiology, Orthostatic hypotension, Vasoconstriction, Postural orthostatic tachycardia syndrome, Ehlers-Danlos syndrome, Arnold-Chiari malformation, Orthostatic intolerance

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Chiari malformations are structural defects in which portions of the cerebellum are located below the foramen magnum. Of the four types of Chiari malformation, emergency physicians are most likely to encounter Type I (Chiari I). Chiari I malformations may be congenital or acquired. Congenital Chiari I malformations are most frequently encountered in the emergency department (ED) setting due to an exacerbation of subacute or chronic Chiari-related symptoms. However, acute Chiari-associated symptoms from an occult congenital or a secondary (acquired) Chiari malformation may occur.

Concepts: Chronic, Congenital disorder, Acute, Congenital disorders, Congenital, Arnold-Chiari malformation

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The authors illustrate the cases of two children with headaches, one diagnosed with Chiari type 1 malformation and the other with hydrocephalus, who played wind instruments. Both patients manifested that their headaches worsened with the efforts made during playing their musical instruments. We briefly comment on the probable role played by this activity on the patients' intracranial pressure and hypothesize that the headaches might be influenced by increases in their intracranial pressure related to Valsalva maneuvers. We had serious doubts on if we should advise our young patients about giving up playing their music instruments.

Concepts: Intracranial pressure, Hydrocephalus, Music, Arnold-Chiari malformation, Musical instrument, Oboe

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BACKGROUND AND PURPOSE: The diagnosis of Chiari malformation type I (CMI) relies on MRI identification of a tonsillar descent (TD) through the foramen magnum, reflecting the overcrowding of an underdeveloped posterior cranial fossa (PCF). However, TD occurs in some patients with normal-sized PCF and, conversely, some patients with borderline or no TD have small PCF. We thus sought to identify a set of prototypic PCF measures for the diagnosis of CMI. METHODS: We performed nineteen measurements of the PCF on sagittal MRI of 100 cases with cerebellar TD ≥5 mm and 50 control individuals, compared the average values in both cohorts and used logistic regression to devise a probability model to predict CMI status. RESULTS: Significant decrements were detected for several PCF-related measures in the patients' cohort. We developed a probability model that combined seven of these parameters to predict diagnosis with 93% sensitivity and 92% specificity. CONCLUSIONS: The addition of simple morphometric measurements in the diagnostic work-up of patients with suspected CMI may facilitate radiological diagnosis. Moreover, identification of the subset of CMI that arise from basichondrocranium underdevelopment is important for both, selection of the most appropriate therapeutic approach as well as proper CMI categorization in research studies.

Concepts: Regression analysis, Positive predictive value, Type I and type II errors, Sensitivity and specificity, Foramen magnum, Arnold-Chiari malformation, Posterior cranial fossa

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Object Ventriculoperitoneal (VP) shunt placement remains the mainstay treatment for pediatric hydrocephalus. These devices have a relatively high complication and failure rate, often requiring multiple revisions. The authors present a single institution’s experience of pediatric patients treated with VP shunts. With an average follow-up time of 20 years, this study is among the longest reports of VP shunt revision in the literature to date. Hydrocephalus origins, shunt revision rates, and causes of shunt failure are described. Patients who underwent their first shunt revision more than 10 years after initial shunt placement were also explored. Methods A retrospective chart review was performed on all pediatric patients who underwent VP shunt placement from January 1990 through November 1996 at the University of Rochester Medical Center. Only patients who had at least 15 years of follow-up since their initial shunting procedure were included. Results A total of 234 procedures were performed on 64 patients, with a mean follow-up of 19.9 years. Patients ranged from a few days to 17.2 years old when they received their original shunt, with a median age of 4 months; 84.5% of the patients required 1 or more shunt revisions and 4.7% required 10 or more. Congenital defects, Chiari Type II malformations, tumors, and intraventricular hemorrhage were the most common causes of hydrocephalus. Overall, patients averaged 2.66 revisions, with proximal (27%) and distal (15%) catheter occlusion, disconnection (11%), and infection (9%) comprising the most common reasons for shunt malfunction. Notably, 12.5% of patients did not require their first shunt revision until more than 10 years after initial device placement, a previously undescribed finding due to the short follow-up duration in previous studies. Conclusions This long-term retrospective analysis of pediatric VP shunt placement revealed a relatively high rate of complications with need for shunt revision as late as 17 years after initial placement. Catheter occlusion represented a significant percentage of shunt failures. Cerebrospinal fluid shunting has a propensity for mechanical failure and patients with VP shunts should receive follow-up through the transition to adulthood.

Concepts: Intracranial pressure, Cerebrospinal fluid, Failure, Congenital disorder, Hydrocephalus, Congenital disorders, Arnold-Chiari malformation, Cerebral shunt

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Object The association of Chiari malformation Type I (CM-I) with syndromic craniosynostosis (SC) in children is well established. Central sleep apnea (CSA) may subsequently occur. However, sleep studies performed in these patients have been focused mainly on assessing the severity of obstructive sleep apnea. Therefore, the incidence and management of CSA in these patients remains poorly defined. Authors of this study aimed to assess the efficacy of foramen magnum decompression (FMD) in resolving CSA, initially detected incidentally, in a small cohort of patients with CM-I and SC. Methods The clinical data for 5 children who underwent FMD for CSA at Alder Hey Children’s Hospital between December 2007 and December 2009 were retrospectively analyzed. Outcomes were evaluated with respect to FMDs by utilizing pre- and postdecompression sleep studies. Of the 5 patients, 2 had Crouzon syndrome and 3 had Pfeiffer syndrome. Results Patient age at the time of surgery ranged from 1.1 to 12.6 years (median 4.1 years). The median postoperative follow-up was 3.6 years. Sleep studies revealed that 2 children experienced a > 80% reduction in CSAs at 1.5 and 21 months after decompression. The remaining 3 children experienced a > 60% reduction in CSAs when reevaluated between 2 and 10 months after decompression. The associated central apnea index improved for all patients. Conclusions Findings suggested that FMD is an effective treatment modality for improving CSA in patients with SC and associated CM-I. The use of multimodal polysomnography technology may improve the evaluation and management of these patients.

Concepts: Sleep, Sleep disorder, Sleep apnea, Polysomnography, Obstructive sleep apnea, Sleep medicine, Arnold-Chiari malformation, Alder Hey Children's Hospital

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We present a 16-year-old male patient with Marfan’s syndrome who presented with quadriparesis from a Type I Chiari malformation (CM) with basilar invagination and a syrinx. The condition resolved after transoral odontoidectomy and occipitocervical fusion without posterior decompression of the CM. Thus, ventral decompression alone can resolve a cervical syrinx in patients with compression of the foramen magnum.

Concepts: Syndromes, Vertebral artery, Ehlers-Danlos syndrome, Arnold-Chiari malformation, Syringomyelia

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Object This study aims to show the relationship between clinical outcome in patients who underwent surgical decompression for Chiari malformation (CM) and postoperative imaging studies, with particular emphasis on the subarachnoid cisterns of the posterior fossa. Methods One hundred seventy-seven patients with CM, including 97 with syringomyelia, underwent posterior fossa decompressive surgery. Both the dura and arachnoid were opened in 150 of these patients, and 135 underwent reduction of the cerebellar tonsils. The patients' clinical signs and symptoms were evaluated at 2 time points after surgery. Their imaging studies were analyzed specifically for the size of the retrotonsillar and subtonsillar cisterns and the syringomyelic cavities. The authors evaluated the relationship between these imaging findings and clinical parameters. Results Clinical improvement correlated strongly with enlargement of the subarachnoid cisterns, and enlargement of the cisterns also correlated with reduction in size of the syrinx cavities. Symptoms related to syringomyelia responded to reduction in size of the syrinx cavities. Conclusions Surgical decompression of the posterior fossa should aim to create relatively large subarachnoid cisterns and reduce the size of the syrinx cavity. Reduction of the cerebellar tonsils by surgical means, together with duraplasty, achieves this goal and thereby improves the clinical outcome for patients with CM. An incidental observation of the study is that obesity increases the likelihood of headache in patients with CM.

Concepts: Medicine, Symptom, Medical diagnosis, Medical sign, Meninges, Arnold-Chiari malformation, Syringomyelia, Dura mater