Syrinx location and size according to etiology: identification of Chiari-associated syrinx.

Strahle J, Muraszko KM, Garton HJ, Smith BW, Starr J, Kapurch JR 2nd, Maher CO. (2015) Syrinx location and size according to etiology: identification of Chiari-associated syrinx.

J Neurosurg Pediatr. 2015 Apr 3:1-9.

Abstract

OBJECT Syrinx size and location within the spinal cord may differ based on etiology or associated conditions of the brain and spine. These differences have not been clearly defined. METHODS All patients with a syrinx were identified from 14,118 patients undergoing brain or cervical spine imaging at a single institution over an 11-year interval. Syrinx width, length, and location in the spinal cord were recorded. Patients were grouped according to associated brain and spine conditions including Chiari malformation Type I (CM-I), secondary CM (2°CM), Chiari malformation Type 0 (CM-0), tethered cord, other closed dysraphism, and spinal tumors. Syringes not associated with any known brain or spinal cord condition were considered idiopathic. Syrinx characteristics were compared between groups. RESULTS A total of 271 patients with a syrinx were identified. The most common associated condition was CM-I (occurring in 117 patients [43.2%]), followed by spinal dysraphism (20 [7.4%]), tumor (15 [5.5%]), and tethered cord (13 [4.8%]). Eighty-three patients (30.6%) did not have any associated condition of the brain or spinal cord and their syringes were considered idiopathic. Syringes in patients with CM-I were wide (7.8 ± 3.9 mm) compared with idiopathic syringes (3.9 ± 1.0, p < 0.0001) and those associated with tethered cord (4.2 ± 0.9, p < 0.01). When considering CM-I-associated and idiopathic syringes, the authors found that CM-I-associated syringes were more likely to have their cranial extent in the cervical spine (88%), compared with idiopathic syringes (43%; p < 0.0001). The combination of syrinx width greater than 5 mm and cranial extent in the cervical spine had 99% specificity (95% CI 0.92-0.99) for CM-I-associated syrinx. CONCLUSIONS Syrinx morphology differs according to syrinx etiology. The combination of width greater than 5 mm and cranial extent in the cervical spine is highly specific for CM-I-associated syringes. This may have relevance when determining the clinical significance of syringes in patients with low cerebellar tonsil position.

Sleep-disordered breathing in patients with myelomeningocele.

Patel DM, Rocque BG, Hopson B, Arynchyna A, Bishop ER, Lozano D, Blount JP.  (2015) Sleep-disordered breathing in patients with myelomeningocele.

J Neurosurg Pediatr. 2015 Apr 3:1-6.

Abstract

OBJECT A paucity of literature examines sleep apnea in patients with myelomeningocele, Chiari malformation Type II (CM-II), and related hydrocephalus. Even less is known about the effect of hydrocephalus treatment or CM-II decompression on sleep hygiene. This study is an exploratory analysis of sleep-disordered breathing in patients with myelomeningocele and the effects of neurosurgical treatments, in particular CM-II decompression and hydrocephalus management, on sleep organization. METHODS The authors performed a retrospective review of all patients seen in their multidisciplinary spina bifida clinic (approximately 435 patients with myelomeningocele) to evaluate polysomnographs obtained between March 1999 and July 2013. They analyzed symptoms prompting evaluation, results, and recommended interventions by using descriptive statistics. They also conducted a subset analysis of 9 children who had undergone polysomnography both before and after neurosurgical intervention. RESULTS Fifty-two patients had polysomnographs available for review. Sleep apnea was diagnosed in 81% of these patients. The most common presenting symptom was "breathing difficulties" (18 cases [43%]). Mild sleep apnea was present in 26 cases (50%), moderate in 10 (19%), and severe in 6 (12%). Among the 42 patients with abnormal sleep architecture, 30 had predominantly obstructive apneas and 12 had predominantly central apneas. The most common pulmonology-recommended intervention was adjustment of peripheral oxygen supplementation (24 cases [57%]), followed by initiation of peripheral oxygen (10 cases [24%]). In a subset analysis of 9 patients who had sleep studies before and after neurosurgical intervention, there was a trend toward a decrease in the mean number of respiratory events (from 34.8 to 15.9, p = 0.098), obstructive events (from 14.7 to 13.9, p = 0.85), and central events (from 20.1 to 2.25, p = 0.15) and in the apnea-hypopnea index (from 5.05 to 2.03, p = 0.038, not significant when corrected for multiple measures). CONCLUSIONS A large proportion of patients with myelomeningocele who had undergone polysomnography showed evidence of disordered sleep on an initial study. Furthermore, 31% of patients had moderate or severe obstructive sleep apnea. Myelomeningocele patients with an abnormal sleep structure who had undergone nonoperative treatment with peripheral oxygen supplementation showed improvement in the apnea-hypopnea index. Results in this study suggested that polysomnography in patients with myelomeningocele may present an opportunity to detect and classify sleep apnea, identify low-risk interventions, and prevent future implications of sleep-disordered breathing.

Comparison of prenatal and postnatal treatments of spina bifida in Poland - a randomized, single-center study

Zamłyński J, Olejek A, Bohosiewicz J, Koszutski T, Ziomek G, Horzelska E, Gajewska-Kucharek A, Maruniak-Chudek I, Herman-Sucharska I, Kluczewska E, Horak S, Bodzek P, Zamłyński M, Kowalik J, Horzelski T. (2013).  Comparison of prenatal and postnatal treatments of spina bifida in Poland - a randomized, single-center study.

Journal of Maternal-Fetal and Neonatal Medicine. 2013 Oct 25. [Epub ahead of print]

Abstract

Abstract Objective: The aim of the study was a randomized comparison of the outcomes of intrauterine myelomeningocele repairs (IUMR) in type II Chiari malformation (II CM) fetuses with clinical data of newborns and infants operated on postnatally. Methods: The study group (SG) comprised of 46 pregnant women whose type II CM children underwent IUMR, while 47 pregnant women whose type II CM children were operated on postnatally constituted the control group (CG). A total of 24 SG and 20 CG patients reached the endpoint of the study. Results: High incidence of PROM (24 (52.2%), CI 3.74 (1.69-8.26) (p<0 .001="" 0.35="" 1.86="" 16="" able="" adaptive="" adverse="" after="" and="" are="" as="" can="" cg="" chiari="" children="" ci="" closure="" compared="" conclusions:="" contrast="" controls.="" controls="" course="" equipment.="" especially="" evolution="" for="" from="" further="" group="" ii="" implantation="" in="" independently.="" ipprom="" iumr.="" iumr="" labor="" lower="" lowers="" malformation.="" measures="" mmc="" need="" needed="" none="" noted="" of="" on="" p="" postnatally="" postoperative="" prenatal="" preterm="" preventive="" respectively="" shunt="" significantly="" statistically="" studies="" study="" surgeries="" the="" to="" treated="" two="" type="" vp="" walk="" was="" without="">

 

PMID:24156622

Aggressive surgical management of patients with Chiari II malformation and brainstem dysfunction.

Rahman M, Perkins LA, Pincus DW. Aggressive surgical management of patients with Chiari II malformation and brainstem dysfunction. Pediatric Neurosurgery. 2009;45(5):337-44. 11.

BACKGROUND/AIMS:
Chiari II malformation represents a group of developmental abnormalities involving the caudal displacement of the cervicomedullary junction, pons, fourth ventricle, and medulla. This constellation of malformations is strongly associated with myelomeningocele (MM) and is a known cause of neurologic deterioration in older MM patients. We describe the evaluation and management of 4 adult MM patients who presented with brainstem compression and a retroflexed odontoid who were subject to aggressive surgical management including occipitocervical (OC) fusion with good clinical results.

METHODS:
Four MM patients who underwent OC fusion for new-onset brainstem dysfunction and myelopathy were identified in the practice of the principal investigator (D.W.P.) from 2003 to 2008.

RESULTS:
The initial evaluation of these patients included consideration of other diagnoses, such as hydrocephalus due to shunt malfunction and tethered cord. These patients were treated with aggressive surgical management. In some cases, multiple surgeries were performed. All 4 patients were treated with cervical decompression and OC fixation and initially had good outcomes. No patients required transoral decompression. Three of the 4 had stable improvement at their last follow-up appointment (mean follow-up of 9 months).

CONCLUSION:
Late deterioration in older MM patients may be secondary to brainstem or cervical spinal cord compression from ventral odontoid compression and Chiari II malformation, hydrocephalus, hydromyelia, or tethered cord. These patients may benefit from more than one surgery. Posterior decompression and OC fusion can avoid a morbid transoral odontoid resection, greatly improve patients' symptoms and prevent further neurologic decline.

PMID: 19907196

Symptom recurrence after suboccipital decompression for pediatric Chiari I malformation: analysis of 256 consecutive cases.

McGirt MJ, Attenello FJ, Atiba A, Garces-Ambrossi G, Datoo G, Weingart JD, Carson B, Jallo GI. Symptom recurrence after suboccipital decompression for pediatric Chiari I malformation: analysis of 256 consecutive cases. Childs Nerv Syst. 2008 Nov;24(11):1333-9.

OBJECTIVE:
Symptom recurrence remains a problem for some patients after surgical decompression for Chiari I malformation. We set out to identify variables at presentation that could identify subgroups most likely to experience incomplete symptom relief after hindbrain decompression for Chiari I malformation.

MATERIALS AND METHODS:
We retrospectively reviewed the records of all pediatric patients undergoing first-time suboccipital decompression for Chiari I malformation over a 10-year period. Measured outcomes included (1) persistence or recurrence of symptoms regardless of severity and (2) need for revision decompression.

RESULTS:
Two hundred fifty-six children (10 5 years old) underwent surgery for Chiari I malformation and were followed up for a mean of 27 months. Presenting symptoms included headache in 192 (75%) patients and brainstem or cranial nerve symptoms in 68 (27%) patients. Fifty-seven (22%) patients experienced mild to moderate symptom recurrence. Nineteen (7%) patients required revision decompression for significant symptom recurrence. Headache was 70% more likely to persist or recur versus cranial nerve or brainstem symptoms (relative risk 1.70, p < 0.05). Vertigo and frontal headache independently increased the odds of symptom recurrence 2.9- and 1.5-fold, respectively. Each increasing year of preoperative headache duration was independently associated with 15% increase in likelihood of symptom persistence (p < 0.05). Severe tonsilar ectopia (caudal to C2 lamina) was twice as likely to require revision decompression (14% versus 6%). CONCLUSION: In our experience, recurrence of mild symptomatology not severe enough to justify revision surgery may occur in nearly a fifth of patients after surgery. Headache was more likely to recur than objective cranial nerve or brainstem symptoms. Increasing duration of headaches, frontal headaches, and vertigo may be more refractory symptoms of Chiari I malformation. PMID: 18516609

Brainstem dysfunction in chiari malformation presenting as profound hypoglycemia: presentation of four cases, review of the literature, and conjecture as to mechanism.

Rekate HL, Nadkarni TD, Teaford PA, Wallace D.
Brainstem dysfunction in chiari malformation presenting as profound hypoglycemia: presentation of four cases, review of the literature, and conjecture as to mechanism. Neurosurgery. 1999 Aug;45(2):386-91. Review.

OBJECTIVE:
We report four patients whose cases resulted in our observation that profound hypoglycemia resulting from intermittent hyperinsulinism plays a significant role in patients with brainstem dysfunction from Chiari I or II malformations who have intermittent autonomic dysfunction ("blue spells").

METHODS:
The records of four children with severe brainstem dysfunction associated with hindbrain herniation (Chiari I or II malformation) were reviewed retrospectively. Each patient had severe lower cranial nerve dysfunction that required tracheotomy and feeding tube placement. After we found that profound hypoglycemia had occurred during a spell of autonomic dysfunction in one patient, the charts of the other three patients were reviewed for evidence of hypoglycemia. Now, whenever one of them has evidence of autonomic dysfunction, prospective studies of glucose and insulin levels are performed. Three of the patients had Chiari II malformation in association with myelomeningocele, and one patient had a Chiari I malformation resulting from Pfeiffer's syndrome.

RESULTS:
Hypoglycemia occurred in these patients episodically, and usually when their shunts were functioning. The hypoglycemia was associated with hyperinsulinemia in each patient. The brainstem structures of these children (presumably the dorsal motor nuclei of the vagus) were extremely sensitive to changes in local or regional intracranial pressure. These changes were triggered by intermittent shunt failure, agitation from pain, abdominal distention from constipation, and retention of CO2. In patients with Chiari malformations, even mild increases in intracranial pressure lead to brainstem dysfunction. One possible explanation is that pressure on the deformed Xth cranial nerve nuclei may lead to insulin release and life-threatening hypoglycemia. Continuous-drip feeds are necessary to prevent this complication.

CONCLUSION:
Patients with severe intermittent brainstem dysfunction after decompression of Chiari I or Chiari II malformations should have laboratory studies of glucose levels performed at the time of the episodes to rule out hypoglycemia.


PMID: 10449086

Cognitive and functional outcome in spina bifida-Chiari II malformation.

Jenkinson MD, Campbell S, Hayhurst C, Clark S, Kandasamy J, Lee MK, Flynn A, Murphy P, Mallucci CL.
Cognitive and functional outcome in spina bifida-Chiari II malformation.
Childs Nerv Syst. 2010 Dec 31.


PURPOSE: The long-term outcome in spina bifida-Chiari II-hydrocephalus complex is poorly understood. Traditional neurosurgical outcome measures are crude. Neuropsychological testing is increasingly important in outcome assessment. We investigated the health, disability, lifestyle and cognitive function in adults who had myelomeningocoele closure at birth.

METHODS: Adult patients under routine follow-up were assessed in a joint neurosurgery/neuropsychology clinic. Patients completed lifestyle questionnaires, the hydrocephalus outcome questionnaire (HOQ) and underwent cognitive testing. Clinical variables including number of shunt revisions, shunt infection and surgical decompression of foramen magnum, which may influence outcome, were investigated.

RESULTS: Twenty-one adults with a median age of 35 years were investigated. All had treated hydrocephalus, and eight had foramen magnum decompression for headache or progressive brainstem symptoms with stabilisation of symptoms in seven and improvement in one. Only eight patients were living independently, five were in paid employment and five work voluntarily. HOQ scores for cognitive function were lower (0.56 ± 0.20; mean ± standard deviation (SD)) than those for physical (0.64 ± 0.15) and social-emotional (0.65 ± 0.17) health. Cognitive function varied across the cohort with attention most severely affected (73.9 ± 17.0; mean ± SD). Repeated episodes of shunt malfunction or foramen magnum decompression were not associated with a worse cognitive function.

CONCLUSIONS: Despite intervention in childhood and adequate cerebrospinal fluid diversion the prognosis for independent living into adulthood remains poor. All patients have elements of cognitive impairment. Structural brain abnormalities may be more important determinants of cognitive outcome than shunt malfunction.



PMID: 21193992

Reversal of hindbrain herniation after maternal-fetal surgery for myelomeningocele subsequently impacts on brain stem function.

Danzer E, Finkel RS, Rintoul NE, Bebbington MW, Schwartz ES, Zarnow DM, Adzick NS, Johnson MP. (2009) Reversal of hindbrain herniation after maternal-fetal surgery for myelomeningocele subsequently impacts on brain stem function. Neuropediatrics. 2008 Dec;39(6):359-62.

The Center for Fetal Diagnosis and Treatment, The Children's Hospital of Philadelphia and The University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.

The aim of our study was to delineate whether the reversal of hindbrain herniation (HH) following fetal myelomeningocele (fMMC) closure subsequently reduces the incidence and severity of HH-associated brainstem dysfunction (BSD). Prior to the NIH-sponsored Management of Myelomeningocele Study (MOMS) trial, 54 children underwent fMMC closure at our institution. Forty-eight (89%) families participated in a structured survey focusing on HH-associated BSD (e.g., apnea, neurogenic dysphagia [ND], gastro-esophageal reflux disease [GERD], neuro-ophthalmologic disturbances [NOD]). Median age at follow-up was 72 months (range: 46-98). Fifty-percent required shunting. HH-related symptoms were completely absent in 15 (63%) non-shunted and 10 (42%) shunted children (P=0.15). No HH-related death occurred and none developed severe persistent cyanotic apnea. ND was reported in 2 (8%) non-shunted and 9 (38%) shunted infants (P=0.03). Mild GERD (medically managed) developed in 2 (8%) without and 6 (25%) with shunt placement (P=0.24). NOD was found in 6 (25%) and 13 (54%) of non-shunted and shunted children, respectively (P=0.07). The majority of fMMC children developed no or only mild BSD at follow-up. Our data support the hypothesis that neurodevelopmental deficits associated with MMC are at least partially acquired and that reversal of HH following fMMC surgery may help to reduce the incidence and severity of BSD.

PMID: 19569004

The Chiari malformations: A constellation of anomalies

Robert M. Shuman RM. (1995) The Chiari malformations: A constellation of anomalies. Seminars in Pediatric Neurology. 1995 Sep;2(3):220-6. Review.


The Chiari malformations form a group of abnormalities that are pathogenetically interrelated. The most important member of the group is the Chiari type II malformation, known as the Arnold-Chiari malformation. Its cardinal features are the myelomeningocele in the thoraco-lumbar spine, the venting of the intracranial cerebrospinal fluid through the central canal, the hypoplasia of the posterior fossa, the herniation of hindbrain into the cervical spinal canal, and the compressive damage to cranial nerves. Some of the abnormalities are progressive, and thus treatable. Limitation of progression may improve outcomes. The challenges to our treatment programs involve early diagnosis, delivery by Caesarean section, emergent closure of the neural plaque and prophylaxis of hydrocephalus, anticipatory prevention of the neurological compression syndromes, multidisciplinary teams, and age-appropriate interventions.

A unifying hypothesis of hydrocephalus, Chiari malformation, syringomyelia, anencephaly and spina bifida

Williams H. A unifying hypothesis of hydrocephalus, Chiari malformation, syringomyelia, anencephaly and spina bifida. Cerebrospinal Fluid Research. 2008 Apr 11;5(1):7

ABSTRACT: This review is a modified version of the Casey Holter Memorial prize essay presented to the Society for Research into Hydrocephalus and Spina Bifida, June 29th 2007, Heidelberg, Germany. It describes the origin and consequences of the Chiari malformation, and proposes that hydrocephalus is caused by inadequate central nervous system (CNS) venous drainage. A new hypothesis regarding the pathogenesis, anencephaly and spina bifida is described. Any volume increase in the central nervous system can increase venous pressure. This occurs because veins are compressible and a CNS volume increase may result in reduced venous blood flow. This has the potential to cause progressive increase in cerebrospinal fluid (CSF) volume. Venous insufficiency may be caused by any disease that reduces space for venous volume. The flow of CSF has a beneficial effect on venous drainage. In health it moderates central nervous system pressure by moving between the head and spine. Conversely, obstruction to CSF flow causes localised pressure increases, which have an adverse effect on venous drainage. The Chiari malformation is associated with hindbrain herniation, which may be caused by low spinal pressure relative to cranial pressure. In these instances, there are hindbrain-related symptoms caused by cerebellar and brainstem compression. When spinal injury occurs as a result of a Chiari malformation, the primary pathology is posterior fossa hypoplasia, resulting in raised spinal pressure. The small posterior fossa prevents the flow of CSF from the spine to the head, as blood enters the central nervous system during movement. Consequently, intermittent increases in spinal pressure caused by movement, result in injury to the spinal cord. It is proposed that posterior fossa hypoplasia, which has origins in fetal life causes syringomyelia after birth and leads to damage to the spinal cord in spina bifida. It is proposed that hydrocephalus may occur as a result of posterior fossa hypoplasia, where raised pressure occurs as a result of obstruction to flow of CSF from the head to the spine, and cerebral injury with raised pressure occurs in anencephaly by this mechanism. The current view of dysraphism is that low central nervous system pressure and exposure to amniotic fluid, damage the central nervous system. The hypothesis proposed in this essay supports the view that spina bifida is a manifestation of progressive hydrocephalus in the fetus. It is proposed that mesodermal growth insufficiency influences both neural tube closure and central nervous system pressure, leading to dysraphism.

PMID: 18405364

Assessment of brainstem function in Chiari II malformation utilizing brainstem auditory evoked potentials (BAEP), blink reflex and masseter reflex.

Koehler J, Schwarz M, Boor R, Hölker C, Hopf HC, Voth D, Urban PP, Ermert A. Assessment of brainstem function in Chiari II malformation utilizing brainstem auditory evoked potentials (BAEP), blink reflex and masseter reflex. Brain Development. 2000 Oct;22(7):417-20.

Brainstem dysfunction was evaluated in 67 patients with myelomeningocele and Chiari II malformation using brainstem auditory evoked potentials (BAEP), blink reflex (BR) and masseter reflex (MR). Signs and symptoms related to Chiari II malformation were observed in 18 patients while 49 patients had normal brainstem findings. BAEP and BR showed a higher sensitivity of brainstem involvement than MR (BAEP=1.0, BR=0.83, MR=0.50). BR, and in particular, MR were of higher accuracy (BR=0.52, MR=0.72) than BAEP (0.39) in separating patients with brainstem signs and symptoms related to Chiari II malformation. We feel that this is due to anatomic and physiologic peculiarities of the brainstem structures mediating BR and MR. Our results suggest that brainstem reflexes can support the decision of further treatment.

PMID: 11102725

Full Text

Brain stem auditory-evoked potentials in meningomyelocele. Natural history of Chiari II malformations

Nishimura T, Mori K, Uchida Y, Ohira T, Tamura K. Brain stem auditory-evoked potentials in meningomyelocele. Natural history of Chiari II malformations. Child's Nervous System. 1991 Oct;7(6):316-26. Review.

Brain stem auditory-evoked potentials (BAEPs) were recorded in 30 patients with meningomyelocele and shunted hydrocephalus ranging in age from birth to 33 years. Twenty-two of them had Chiari II malformation, one of which was symptomatic. In 22 cases, including 15 with Chiari II malformation, BAEPs were recorded repeatedly after periods ranging from 18 months to 7 years. The results were as follows: (1) III-V interpeak latency (IPL) decreased progressively from prolonged to the normal range with growth until 25 years of age; (2) I-III IPL tended to prolong gradually from the normal range; (3) these findings may indicate that the natural history of Chiari II malformation is delayed maturation of the brain stem and intensification in the elongation and stretching of the hindbrain and lower cranial nerves.

PMID: 1764707

Electrophysiological studies on brainstem function in patients with myelomeningocele

Mori K, Nishimura T. Electrophysiological studies on brainstem function in patients with myelomeningocele. Pediatric Neurosurgery. 1995;22(3):120-31.

We investigated the brainstem auditory evoked potentials (BAEPs), somatosensory evoked potentials (SEPs), and electrically elicited blink reflexes (BRs) to evaluate the brainstem function in 31 patients with meyelomeningocele (MMC) including 22 with Chiari type-II malformation. The I-III interpeak latency (IPL) of the BAEPs and the N9-N13 IPL of the SEPs tended to become gradually prolonged from the normal range with increasing age. The III-V IPL of the BAEPs and the N13-N20 IPL of the SEPs were initially prolonged and decreased progressively to the normal range. These findings indicated a gradual latency shortening of the brainstem components and latency prolongation of the peripheral components. Thus, while primary brainstem dysfunction may improve with age, secondary dysfunction due to stretching and elongation of the lower cranial nerves and cervical nerve roots may intensify. The BRs showed an abnormal R2 in 90% of the cases, disclosing subclinical lesions in the medulla oblongata which were not detected by BAEPs alone. BAEPs, SEPs and BRs were combined to yield a functional evaluation of the brainstem and lower cranial nerves that could not be done by magnetic resonance imaging alone. No close relation was found between electrophysiological abnormalities and the degree of hindbrain anomaly by neuroimaging.

PMID: 7786804

Somatosensory evoked potentials to median nerve stimulation in meningomyelocele

Nishimura T, Mori K. Somatosensory evoked potentials to median nerve stimulation in meningomyelocele: what is occurring in the hindbrain and its connections during growth? Childs Nervous System. 1996 Jan;12(1):13-26. Review.

Twenty patients with meningomyelocele (MMC) and shunted hydrocephalus, ranging in age from 3 to 23 years old, underwent serial recording of short-latency somatosensory evoked potentials (SEPs) to median nerve stimulation, on the basis of which to assess the evolution of dysfunction in the brainstem and its connections (cervical spinal cord, cervical nerve roots, lower cranial nerves). Eighteen patients had Chiari type II malformations, none of which was symptomatic. In all 20 patients, serial SEP recordings were obtained repeatedly after periods ranging from 2 to 7 years. The results were as follows: (1) the ratio of EP-N13 interpeak latencies (IPLs) to body height (BH) tended to lengthen gradually after starting in the normal range with growth. (2) In contrast, the ratio N13-N20 IPLs/BH decreased continuously to the normal range with growth, after initial prolongation. These findings and our earlier studies of brainstem auditory evoked potentials suggest that compression and traction result in strangulation of the cervical spinal cord and kinked medulla as well as stretching of the cervical nerve roots and lower cranial nerves. However, primary intrinsic functional disorders of the brainstem appeared to improve gradually during growth. The natural history of Chiari type II malformations involves these opposing dynamic phenomena in the hindbrain and its connections.

PMID: 8869170

Anatomical progression of the Chiari II malformation.

Ruge JR, Masciopinto J, Storrs BB, McLone DG. Anatomical progression of the Chiari II malformation. Childs Nervous System. 1992 Mar;8(2):86-91.

To evaluate whether anatomic change of the relationship of the Chiari II malformation and the cranial base was occurring, 22 children with meningomyelocele had serial MRI scans reviewed. A ratio (B/A) was established between the distance from the foramen magnum to the caudalmost portion of herniated cerebellum (B) and the diameter of the foramen magnum (A) and this ratio was compared on serial MRI scans. Eighteen children had an increase in the B/A ratio, two children had a decrease, and two had no change. This indicates that continuous anatomic change of the Chiari II malformation and the skull base is occurring. Clinical deterioration in the older child may be explained by a combination of compressive and traction forces due to this change.


PMID: 1591752

Seven distinct coexistent cranial and spinal anomalies

Emmez H, Tokgoz N, Dogulu F, Yilmaz MB, Kale A, Baykaner MK. Seven distinct coexistent cranial and spinal anomalies. Pediatric Neurosurgery. 2006;42(5):316-9.

Existence of multiple cranial and spinal anomalies in spina bifida is well known; however, coexistence of seven different severe anomalies is extremely rare. The location of the anomalies, the patient's age and presentation are other interesting aspects of the presented case.

CASE REPORT: A 1-year-old girl with an enlarged head and big, infected lumbosacral myelomeningocele (MMC) was admitted to the emergency department in a comatose state. Further investigations revealed hydrocephalus, Chiari malformation, syringohydromyelia, split cord malformation, dermal sinus tract, lumbosacral MMC, and tethered cord. Unfortunately, the patient died 3 days after admission because of meningitis and sepsis.

DISCUSSION: Coexistence of seven different craniospinal anomalies is extremely unusual. Further investigations with magnetic resonance imaging for associated anomalies, early shunt placement and MMC repair are required to prevent this life-threatening condition in spina bifida.

PMID: 16902346

Critical analysis of the Chiari malformation Type I found in children with lipomyelomeningocele

Tubbs RS, Bui CJ, Rice WC, Loukas M, Naftel RP, Holcombe MP, Oakes WJ. Critical analysis of the Chiari malformation Type I found in children with lipomyelomeningocele. Journal of Neurosurgery. 2007 Mar;106(3 Suppl):196-200.

OBJECT: Occasional comments are found in the literature regarding patients with lipomyelomeningocele and concomitant Chiari malformation Type I (CM-I). The object of this study was to explore the association between these two conditions.

METHODS: The authors performed a retrospective database analysis of lipomyelomeningocele cases to identify cases of concomitant CM-I. Analysis of posterior fossa volume (based on the Cavalieri principle) was performed in all identified cases in which appropriate neuroimages were available, and the results were compared with those obtained in age-matched controls. Seven (13%) of 54 patients with lipomyelomeningocele were found to also have CM-I. Two of these were symptomatic (cervicothoracic syrinx and occipital headaches) and required posterior fossa decompression. No correlation was found between the amount of hindbrain herniation and the level of the conus medullaris or the type of lipomyelome-ningocele (for example, caudal or transitional). Volumetric studies of the posterior fossa revealed normal age-matched volumes in all but one patient (who had asymptomatic CM-I).

CONCLUSIONS: The incidence of CM-I in patients with lipomyelomeningocele appears to be significantly greater than that of the general population and the association rate is too high for the finding to be a chance occurrence. Decreases in the volume of the posterior cranial fossa were not found in the majority of patients in this small cohort; therefore, the cause of the concomitant occurrence of lipomyelomeningocele and CM-I remains undetermined. Clinicians should consider obtaining imaging studies of the entire neuraxis in patients with lipomyelomeningoceles and should investigate other causes for syringes found in association with lipomyelomeningoceles.

PMID: 17465384

Neurobiology of perceptual and motor timing in children with spina bifida in relation to cerebellar volume

Dennis M, Edelstein K, Hetherington R, Copeland K, Frederick J, Blaser SE, Kramer LA, Drake JM, Brandt M, Fletcher JM. Neurobiology of perceptual and motor timing in children with spina bifida in relation to cerebellar volume. Brain. 2004 Jun;127(Pt 6):1292-301. Epub 2004 Apr 6.

The cerebellum is important for perceptual and motor timing in the mature brain, but the timing function of the cerebellum in the immature brain is less well understood. We investigated timing in children with spina bifida meningomyelocele (SB), a neural tube defect that involves cerebellar dysgenesis, and in age-matched controls. Specifically, we studied perceptual timing (judgements of 400 ms duration) and motor timing (isochronous motor tapping); measured cerebellar volumes; and related perceptual and motor timing to each other and to cerebellar volume measurements. Children with SB had impairments in the perception of duration (around 400 ms) but not frequency (around 3000 Hz), showing that their perceptual timing deficit was not a generalized auditory impairment. Children with SB had motor timing deficits on unpaced but not paced isochronous tapping, and their unpaced timing performance was associated with clock variance rather than with motor implementation. Perceptual and motor timing were correlated, suggesting that children with SB have impairments in a central timing mechanism. Children with SB, especially those with upper spinal cord lesions, had significant cerebellar volume reductions in grey and white matter, as well as different regional patterns of grey matter, white matter and CSF. Duration perception was correlated with cerebellar volumes, and the number of valid tapping trials was correlated with cerebellar volumes in the SB group, which data demonstrate structure-function relations between timing and cerebellar volumes.

PMID: 15069019
Full Text Online

Space-based inhibition of return in children with spina bifida

Dennis M, Edelstein K, Copeland K, Frederick JA, Francis DJ, Hetherington R, Blaser SE, Kramer LA, Drake JM, Brandt ME, Fletcher JM. Space-based inhibition of return in children with spina bifida. Neuropsychology. 2005 Jul;19(4):456-65.

Inhibition of return (IOR) refers to an increase in time to react to a target in a previously attended location. Children with spina bifida meningomyelocele (SBM) and hydrocephalus have congenital dysmorphology of the midbrain, a brain region associated with the control of covert orienting in general and with IOR in particular. The authors studied exogenously cued covert orienting in 8- to 19-year-old children and adolescents (84 with SBM and 37 age-matched, typically developing controls). The exogenous cue was a luminance change in a peripheral box that was 50% valid for the upcoming target location. Compared with controls, children with SBM showed attenuated IOR in the vertical plane, a deficit that was associated with midbrain dysmorphology in the form of tectal beaking but not with posterior brain volume loss. The data add to the emerging evidence for SBM deficits in attentional orienting to salient information. (c) 2005 APA, all rights reserved.

PMID: 16060820

The Chiari II malformation: cause and impact

McLone DG, Dias MS. The Chiari II malformation: cause and impact. Child's Nervous System. 2003 Aug;19(7-8):540-50. Epub 2003 Aug 12.

INTRODUCTION: It is the Chiari II malformation and its effects that determine the quality of life of the individual born with spina bifida.

DISCUSSION: The cause of this malformation has been a source of debate for many years. Understanding the cause enables strategies for the management of problems created by this malformation to be developed. An open neural tube defect allows fluid to escape from the cranial vesicles, altering the intracranial environment and leads to all of the brain changes seen in the Chiari II malformation. Decompression of the intracranial vesicles causes overcrowding, decrease in the size of the third ventricle, and changes in the fetal skull. It also permanently links the intracranial ventricular system to the spinal cord central canal.

PMID: 12920543