1/26. Brainstem dysfunction in chiari malformation presenting as profound hypoglycemia: presentation of four cases, review of the literature, and conjecture as to mechanism.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.- - - - - - - - - - ranking = 1keywords = hindbrain (Clic here for more details about this article) |
2/26. Prepontine lesions with chiari II malformation. Report of two cases.In 2 cases of infants with the Chiari II malformation, a prepontine cyst presented in association with the hindbrain abnormalities characteristic of the Chiari II syndrome. Both infants presented with bulbar dysfunction and had poor outcome despite decompression of the cerebellar tonsillar herniation and drainage of the prepontine cysts. No such association between prepontine lesions and Chiari II has been described previously.- - - - - - - - - - ranking = 1keywords = hindbrain (Clic here for more details about this article) |
3/26. Vanishing cerebellum in myelomeningocoele.Reduced hindbrain herniation observed after intrauterine myelomeningocoele repair suggests that posterior fossa changes in myelomeningocoele are secondary results of prolonged prenatal spinal cerebrospinal fluid leak. Exceptionally, this transforaminal herniation results in 'degeneration' of cerebellar tissue, presumably due to mechanically induced ischaemia. This phenomenon was called 'vanishing cerebellum in Chiari II malformation'. We report three similar cases of this apparently rare finding. Pregnancies were normal. Cerebellar hypoplasia was already recognized in one instance by prenatal ultrasound at gestational week 25. Postnatal imaging was similar in all three patients showing small posterior fossa, beaked midbrain tectum, small brainstem without pontine prominence, reduced cerebellar tissue with virtual absence of one hemisphere and supratentorial hydrocephalus. Our series is too small to draw firm conclusions about predisposing risk factors for and consequences of vanishing cerebellum. Cerebellar damage can interfere with cognitive development, as shown in children with cerebellar agenesis/ hypoplasia, congenital ataxia and small cerebellum following prematurity. A final conclusion on the cognitive consequence of vanishing cerebellum cannot be drawn on the available literature and our limited observations, as one of our patients died at 3 months and another is still too young for appropriate testing. However, the third (aged 15 years) is very severely retarded.- - - - - - - - - - ranking = 1keywords = hindbrain (Clic here for more details about this article) |
4/26. Chiari I malformation in the very young child: the spectrum of presentations and experience in 31 children under age 6 years.INTRODUCTION: The entity of hindbrain herniation without myelodysplasia in the very young child has been poorly described. A retrospective analysis of children diagnosed with Chiari I malformation (CM I) before their sixth birthday is presented. methods: Since 1985, 31 children with CM I (0.3-5.8) years of age have been diagnosed at University of iowa hospitals and Clinics. Their records were reviewed for presenting symptoms, signs, radiographic findings, treatment, complications, and outcome. RESULTS: The average age at diagnosis was 3.3 years. Sixteen patients were under age 3. Chief presenting complaints included impaired oropharyngeal function (35%), scoliosis (23%), headache or neck pain (23%), sensory disturbance (6%), weakness (3%), and other (10%). Sixty-nine percent of children under age 3 had abnormal oropharyngeal function. Three patients under age 3 (19%) had undergone fundoplication and/or gastrostomy before diagnosis of CM I. Common physical findings included abnormal tendon reflexes (68%), scoliosis (26%), abnormal gag reflex (13%), and normal examination (13%). vocal cord dysfunction (26%, all under age 3) and syringohydromyelia (52%) were also seen. Twenty-five patients were treated surgically at our institution with posterior fossa decompression, duraplasty, and cerebellar tonsillar shrinkage. Three patients were lost to follow-up. Ninety-one percent of patients reported improved symptomatology at last follow-up (mean: 3.9 years). Three patients required reoperation for recurrence of symptoms. syringomyelia improved in all patients. scoliosis resolved in 2 of 8 patients, improved in 5, and stabilized in 1. There was no permanent morbidity from surgery. DISCUSSION: We show that children with Chiari I abnormality are very likely to present with oropharyngeal dysfunction if under age 3, and either scoliosis or headache or neck pain worsened by valsalva if age 3 to 5. These symptoms are very likely to improve after Chiari decompression, which can be done with low morbidity. CONCLUSIONS: Very young children presenting with oropharyngeal dysfunction, pain worsened by valsalva, or scoliosis should prompt the clinician to consider CM I as a possible cause.- - - - - - - - - - ranking = 1keywords = hindbrain (Clic here for more details about this article) |
5/26. Rhombencephalosynapsis and a Chiari II malformation.Rhombencephalosynapsis is an anomaly of the hindbrain characteristically presenting with cerebellar fusion and absence of cerebellar vermis on magnetic resonance imaging. Its association with spinal anomalies has not been reported previously. We report a unique case, a 22-year-old man with cerebellar fusion associated with a cervicothoracic meningomyelocele, diastematomyelia, tethering of the spinal cord, and dorsal dermal sinuses. In addition, cerebellar tonsillar herniation and tectal beaking similar to that seen in Chiari II malformations were present. These findings suggest that rhombencephalosynapsis can be associated with spinal malformations and, furthermore, that cases with the common features of rhombencephalosynapsis and a Chiari II malformation can exist. Such an association likely represents a new anomaly of the hindbrain and spine.- - - - - - - - - - ranking = 2keywords = hindbrain (Clic here for more details about this article) |
6/26. Cessation of chronic hypertension after posterior fossa decompression in a child with Chiari I malformation. Case report.The authors report on the case of a patient evaluated for valsalva maneuver-induced headache, dizziness, and ataxia. neuroimaging revealed a Chiari I malformation without syringomyelia. A history of idiopathic hypertension was noted. After posterior fossa decompression, pathologically elevated blood pressure was absent, and at 24-month follow-up evaluation the patient remained normotensive. Although seemingly rare, this case illustrates that some patients with tonsillar ectopia may exhibit elevated blood pressure. Clinicians should consider hindbrain herniation a rare cause in idiopathic hypertension.- - - - - - - - - - ranking = 1keywords = hindbrain (Clic here for more details about this article) |
7/26. Acquired Chiari I malformation following baclofen pump placement in a child. Case report.The authors present a case of a child suffering from shunt-treated hydrocephalus and spastic quadriplegia who underwent surgery for placement of a baclofen pump. Magnetic resonance (MR) imaging performed prior to pump placement demonstrated no hindbrain herniation. Afterward, however, the patient exhibited symptoms of brainstem compression, and MR imaging revealed a significant Chiari I malformation along with a fully functioning ventriculoperitoneal shunt. Posterior fossa decompression was performed, and the patient's symptoms abated. The authors believe this to be the first report of an acquired Chiari I malformation in a patient with a baclofen pump. Clinicians should consider Chiari I malformation as a rare but severe complication of baclofen pump placement.- - - - - - - - - - ranking = 1keywords = hindbrain (Clic here for more details about this article) |
8/26. scoliosis in pediatric Chiari malformations without myelodysplasia.A prospective study was undertaken in 1985 to better understand how the surgical manipulation of hindbrain herniation affected abnormal spinal curvature. Eleven patients under 16 years of age with Chiari malformation (not associated with myelodysplasia) and scoliosis of at least 15 degrees were studied. The mean curve angle at the time of original treatment was 29 degrees, with the convexity to the right in seven patients. The curvature was rapidly progressing in four patients. The most common presenting signs were myelopathy and weakness. Investigative procedures included spine radiographs with the patient standing and magnetic resonance (MR) imaging of the brain, spinal cord, and craniovertebral junction. Eight children had associated hydrosyringomyelia. Surgical intervention consisted of a dorsal posterior fossa decompression in all patients and a transoral ventral decompression of the cervicomedullary junction in five. All patients were followed at 3, 6, and 12 months, and at yearly intervals thereafter with clinical evaluations, spine radiographs in the standing position, and postoperative MR imaging. The mean follow-up period was 35 months. The scoliosis improved in eight patients, stabilized in one, and progressed in two. Only one child required postoperative spinal fusion and instrumentation for progression of scoliosis. Hematomyelia or hematobulbia was associated with persistent scoliosis in two patients. The presence of hydrosyringomyelia and bone erosion did not preclude curve improvement. All patients under 10 years of age had resolution of their scoliosis, despite preoperative curves of more than 40 degrees. These findings emphasize the importance of early surgical intervention, with the restoration of normal cerebrospinal fluid dynamics at the craniovertebral junction in children with symptomatic Chiari malformations.- - - - - - - - - - ranking = 1keywords = hindbrain (Clic here for more details about this article) |
9/26. Spontaneous resolution of isolated Chiari I malformation.INTRODUCTION: Spontaneous resolution of Chiari I abnormality is very rare. In most patients, the radiological abnormality either stays unchanged with time or deriorates. CASE REPORT: We present a male patient who was diagnosed at the age of 18 months as having radiological evidence of Chiari I malformation without syringomyelia, which had resolved 5 years later on a subsequent MR scan. At the time of initial diagnosis, he had been experiencing recurrent jerking movements of his body and was a sufferer of chronic renal failure. DISCUSSION: The symptoms were thought to be unrelated to the hindbrain hernia. Such spontaneous resolution of an isolated Chiari I malformation has only been described once more before, although resolution of hindbrain hernia associated with syringomyelia has been described before in several cases, albeit at single figures. The mechanism for such a natural evolution is not clear. CONCLUSION: This patient demonstrates that surgical treatment should not be considered hastily in patients with radiological evidence of Chiari I in the absence of convincing associated clinical symptoms.- - - - - - - - - - ranking = 2keywords = hindbrain (Clic here for more details about this article) |
10/26. Syringobulbia in a pediatric population.OBJECTIVE: To better understand the presentation, management, and outcome of syringobulbia in the pediatric age group. methods: The University of iowa pediatric neurosurgery database was searched for patients under the age of 18 with a diagnosis of syringobulbia. The patients' records were retrospectively reviewed for demographic data, chief complaint and presenting symptoms, neurological and radiographic findings, treatment, outcome, and complications. Children with open neural tube defects and Chiari II malformations were excluded. RESULTS: Six pediatric patients were identified as meeting inclusion criteria. The average age at time of surgery was 14.8 years. The chief complaints were vision impairment in three children and numbness, gait instability, and headache worsened with Valsalva in one patient each. Other prominent symptoms included sleep apnea and weakness. All patients showed at least one cranial nerve dysfunction. Radiographs revealed hindbrain herniation and associated syringomyelia in all cases. Two patients had scoliosis. Treatment was posterior fossa decompression with cerebellar tonsillar shrinkage, opening of foramen of Magendie, and duraplasty. Two patients also required concomitant ventral decompression. The cavity of syringobulbia communicated with syringomyelia and the fourth ventricle in most children but was distinct from the fourth ventricle. Two patients received fourth ventricle to subarachnoid shunts. Follow-up averaged 3.2 years, and all patients clinically improved after surgery. magnetic resonance imaging documented resolution of syringobulbia in all cases, with syringomyelia improving in all cases. There was no permanent morbidity or mortality in the series. CONCLUSION: Syringobulbia is strongly associated with Chiari malformation and syringomyelia, and patients often present because of cranial nerve palsies. Posterior fossa decompression is a safe and effective treatment.- - - - - - - - - - ranking = 1keywords = hindbrain (Clic here for more details about this article) |
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