Supratentorial arachnoid cyst and associated subdural hematoma: neuroradiologic studies

CT and MR images of 8 patients with supratentorial arachnoid cyst complicated by subdural hematoma were studied and compared with those of 8 patients who developed nontraumatic subdural hematoma without arachnoid cyst. Of the 8 patients with supratentorial arachnoid cyst, CT and MR disclosed temporal bulging and/or thinning of the temporal squama in all 6 patients with middle fossa arachnoid cysts, and the thinning of the calvaria was evident in another patient with a convexity cyst. Calvarial thinning at the site corresponding to interhemispheric arachnoid cyst was clearly depicted on coronal MR images. In contrast, none of the 8 young patients with nontraumatic subdural hematoma without arachnoid cyst had abnormal calvaria. Temporal bulging and thinning of the overlying calvaria were identified as diagnostic CT and MR features of arachnoid cyst with complicating intracystic and subdural hemorrhage. Radiologists should be aware of this association and should evaluate the bony structure carefully.     

Linkage and association between a CD4 gene polymorphism and IDDM in Danish IDDM patients. The Danish IDDM Epidemiology and Genetics Group, and The Danish Study Group of Diabetes in Childhood

PURPOSE: Our purpose was to determine the neuroradiologic findings of Marinesco-Sj?gren syndrome on plain skull radiographs, CT, and MR images. METHODS: Eight patients with proved Marinesco-Sj?gren syndrome (age range, 4 to 56 years) had a total of nine CT scans, seven MR imaging studies, and two plain radiographic examinations of the skull. The findings were reviewed retrospectively, with particular attention to the size of the posterior fossa and cerebellum. RESULTS: All patients had hypoplastic cerebellar hemispheres and a hypoplastic vermis in a small posterior fossa. One patient had a midline posterior fossa cyst and another had agenesis of the corpus callosum. CONCLUSION: Hypoplasia of the cerebellar hemispheres and the vermis and a small posterior fossa are the most prominent neuroradiologic findings in Marinesco-Sj?gren syndrome.     

MR of spinal cord ganglioglioma

PURPOSE: Our purpose was to describe the MR imaging features in a series of spinal intramedullary gangliogliomas and to compare these findings with the MR features of intramedullary astrocytomas and ependymomas. METHODS: A retrospective analysis was performed of 76 MR examinations in 27 patients with histologically proved spinal ganglioglioma; these were then compared with imaging findings in a representative sample of histologically proved spinal cord astrocytomas and ependymomas. RESULTS: Statistically significant observations regarding spinal gangliogliomas included young age of the patients (mean, 12 years), long tumor length, presence of tumoral cyst, presence of bone erosion and scoliosis, absence of edema, presence of mixed signal intensity on T1-weighted images, and presence of patchy enhancement and cord surface enhancement. A trend (not statistically significant) was noted for holocord involvement and lack of magnetic susceptibility. CONCLUSION: Spinal ganglioglioma can be strongly suspected if MR images reflect the above criteria; however, the ultimate diagnosis still depends on radical resection and appropriate histopathologic investigation.     

Infratentorial empyema: analysis of 22 cases

OBJECTIVE: Infratentorial empyema is an uncommon form of intracranial suppuration that is usually secondary to neglected otogenic infection. The diagnosis is frequently delayed and often confused with that of meningitis. The associated mortality is distressingly high, yet it has, as a clinical entity, received scant attention in the literature. We present a 13-year experience of this condition. PATIENTS AND METHODS: From a retrospective analysis of 3865 patients with intracranial suppuration during a 13-year period, 22 patients with infratentorial empyema were identified. The inpatient notes for these patients were analyzed with reference to clinical, radiological, bacteriological, operative, and outcome data. RESULTS: Twenty-two patients with infratentorial empyema accounted for 0.6% of admissions caused by intracranial suppuration during the study period. Of these 22 empyemas, 13 were subdural and 9 epidural. Hydrocephalus was present in 17 (77.3%). Except for two epidural empyemas that did not warrant neurosurgical intervention, all patients underwent standard surgical management (wide posterior fossa craniectomy). Nineteen underwent mastoidectomy because the source of infection was otogenic. Concomitant and persistent hydrocephalus was treated aggressively. Five patients died (mortality rate of 22.7%). All fatalities had subdural empyemas, and all three patients with cerebellopontine angle extension of subdural purulent collections died. CONCLUSION: Although rare, infratentorial empyema, especially when subdural, is a lethal disease. Cerebellopontine angle extension of pus was a particularly ominous sign in our experience. Early surgical drainage via wide posterior fossa craniectomy, aggressive treatment of associated hydrocephalus, eradication of the primary source of sepsis, and, finally, intravenous high dosage of appropriate antibiotics form the mainstay of treatment.     

The in vitro effect of hydrocortisone on endocytosis in cultured mouse peritoneal macrophages

Three juvenile patients with cerebellar astrocytomas which have seeded the spinal subarachnoid space are presented. Histologic verification of the similarity between the posterior fossa tumor and its spinal implant was obtained in two of the three patients. The cerebellar tumors in all cases have been benign (grade I),and the behavior, other than their seeding has also been indolent. Review of pertinent literature discloses no similar experience with cerebellar astrocytomas. Aggressive therapy is advocated for the rare patient with subarachnoid seeding from this benign lesion.     

Contrast enhancement and quantitative signal analysis in MR imaging of multiple myeloma: assessment of focal and diffuse growth patterns in marrow correlated with biopsies and survival rates

OBJECTIVE: This study describes infiltration patterns of multiple myeloma in spinal MR imaging and correlates the findings with biopsies, survival rates, and signal intensity measurements in unenhanced and enhanced studies. MATERIALS AND METHODS: Fifty-three patients with multiple myeloma and 53 age-matched controls underwent MR imaging of the spine. Twenty-nine patients underwent sagittal T1-weighted spin-echo enhanced imaging and all patients underwent sagittal T1-weighted spin-echo unenhanced and opposed-phase gradient-recalled echo images, and signal intensity measurements were taken. MR imaging was correlated to marrow specimens (n = 40) and a clinical staging system. The probability of survival was also calculated. Finally, we performed qualitative visual evaluation (infiltration pattern, degree of tumor involvement) and a quantitative evaluation (marrow signal intensity ratios, contrast enhancement). RESULTS: Five infiltration patterns were found: normal-appearing marrow with low-grade interstitial infiltration (n = 5), focal (n = 18), diffuse (n = 12), focal and diffuse (n = 13), and salt-and-pepper (n = 5). Infiltration pattern correlated with clinical staging; all patients with normal-appearing and salt-and-pepper patterns were clinically stage I. Diffuse marrow infiltration was assessed by marrow ratios: low-grade infiltration, greater than 2.0; intermediate, 1.0-2.0; highgrade, less than 1.0. Contrast enhancement with a signal intensity increase greater than 40% indicated diffuse infiltration. In the control group, all of whom had no marrow disease, enhancement varied (mean +/- SD, 16% +/- 8.9%) but did not exceed 40%. Marrow involvement on MR images correlated significantly with clinical staging and survival (p < or = .001). CONCLUSION: MR imaging with opposed gradient-recalled echo sequences and contrast enhancement provided data that allowed us to classify infiltration patterns and to quantify diffuse marrow involvement in multiple myeloma, both of which correlated to clinical staging and biopsy. Also, the MR data was of prognostic value. Therefore, like laboratory parameters, biopsies, and radiographs, MR imaging can be a supporting pillar in staging and planning treatment of patients with multiple myeloma.     

Extra osseous tumors of the spine in children and adolescents. Spinal complications

PURPOSE OF THE STUDY: The delay in diagnosis of spinal tumors is not rare. The chief complaint may include pain, walking disability, and spinal or limb deformities. The purpose of our study is to analyze the spinal deformities associated with non osseous intraspinal tumors, to assess the complications of treatment, and to set out a preventive protocol. MATERIALS: We reviewed retrospectively 40 consecutive cases of non osseous intraspinal tumors treated between 1972 and 1991. There were 32 intradural, 2 extradural, and 6 intra and extradural combined tumors. At the first consultation, the age ranged between 4 months and 15 years, and only 16 patients showed neurologic deficit. Spinal deformity existed in 9 patients, 7 of which had no neurologic deficit. All the tumors were treated surgically. Laminectomy was done in 28 cases, and osteoplastic laminotomy in 12 cases. The number of levels included in the laminectomy ranged from 3 to 18. Bilateral arthrectomy at least at one level was undertaken in 15 cases. A postoperative brace was worn in all cases for an average period of 4 months. An adjuvant radiotherapy was undertaken in 12 cases for an incomplete resection. METHODS: The incidence and pattern of spinal deformity was assessed before tumor treatment and ultimately after laminectomy or osteoplastic laminotomy (or laminoplasty). RESULTS: Among the 9 cases with preexisting spinal deformity, the curve magnitude increased after laminectomy in 4. A kyphotic, kyphosoliotic or scoliotic deformity developed in 18 cases after surgery for tumor resection. Among these 18 patients, only one had had an adequate osteoplastic laminotomy. The treatment of spinal deformities was surgical in 12 cases, and done by either posterior or anterior and posterior combined arthrodesis. DISCUSSION: Spinal deformity may be the main complaint of a patient who has intraspinal tumor. Prevention of postlaminectomy spinal deformity is mandatory, and could be done by osteoplastic laminotomy and the use of a brace during a minimum period of 4 to 6 months after surgery. CONCLUSION: Diagnosis of intraspinal tumors in children and adolescents should be done early, and laminoarthrectomy should be replaced by osteoplastic laminotomy.     

Does the use in animals of antimicrobial agents, including glycopeptide antibiotics, influence the efficacy of antimicrobial therapy in humans?

PURPOSE: To determine if the cerebral cortical vain sign seen on magnetic resonance (MR) images can be used with color Doppler ultrasound (US) to differentiate enlarged subarachnoid space from subdural collection. MATERIALS AND METHODS: Eighteen infants with pericerebral fluid collection were prospectively examined with color Doppler US and MR imaging. Patients were classified into two groups: group A, with positive cortical vein sign (visualization of color-coded cortical veins that cross fluid collections at cerebral convexities); and group B, without the sign. RESULTS: Positive cortical vein sign was seen at US in 12 patients (group A): nine with benign enlargement of subarachnoid spaces, two with brain atrophy, and one with meningococcal meningitis. The veins were displaced and embedded within the echogenic pia-arachnoid that surrounds the brain or were trapped in the subarachnoid spaces between the neo-membrane and cortical surface (group B, negative cortical vein sign) in four patients with meningitis, two victims of child abuse, and one patient with leukemia. Findings from subsequent MR imaging confirmed the color Doppler US findings. CONCLUSION: Color Doppler US depiction of the cortical vain sign appears to be as effective as MR imaging in differentiating enlargement of the subarachnoid fluid space from subdural effusion.     

CT and MR in infants with pericerebral collections and macrocephaly: benign enlargement of the subarachnoid spaces versus subdural collections

PURPOSE: To compare CT and MR in the differentiation of benign enlargement of the subarachnoid spaces and subdural collections in infants with macrocephaly. METHODS: MR was performed in 19 infants with macrocephaly, showing bifrontal enlargement of the subarachnoid spaces on CT. RESULTS: In 11 patients, a single fluid layer could be distinguished on MR of the pericerebral collections, suggesting benign enlargement of the subarachnoid spaces. In eight patients, two separate layers were clearly differentiated, an outer layer that was hyperintense on all sequences and an inner layer with the same intensity as the cerebrospinal fluid. This indicated the presence of subdural collections. These collections were mainly frontal in six and extended over the entire hemisphere in two patients. On CT, these separate lesions were seen only in three patients and missed in three others. In two final patients, CT findings were equivocal with evidence of membrane formation within the hypodense collections. In seven patients with a subdural collection, subdural-external drainage was performed. In three patients, the collection was hemorrhagic. The protein content of the fluid showed a mean of 1381.7 +/- 785.6 mg/dL. The MR and surgical findings of a subdural collection correlated with the absence of a family history of macrocrania, an age under 5 months, and acute clinical signs of vomiting, somnolence, and hypotonia. CONCLUSION: MR appears essential in the differential diagnosis between benign enlargement of the subarachnoid spaces and subdural collections in infants.     

Remote subarachnoid haemorrhage in the posterior fossa following supratentorial surgery. Clinical observation of 6 cases

Haemorrhage in regions remote from the site of following intracranial operations is rare, but they do occur. We performed supratentorial craniotomy on 639 patients between the time of introduction of computed tomography (CT) for clinical use in 1983 and June 1992; subarachnoid haemorrhage (SAH) in the posterior fossa occurred postoperatively in six of these cases. These included four patients with tumours in the sellar region, one with an arteriovenous malformation (AVM) and one who underwent superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis. The ages of the six patients ranged from 17-72 years. Haemorrhage occurred on the day of operation in one case and was detected on CT examination on the day following surgery in the remaining five cases. Of three patients with disturbance of consciousness, two underwent suboccipital craniectomy for reduction of intracranial pressure, while one received barbiturate therapy and later underwent cerebrospinal fluid (CSF) shunt surgery. No special treatment was necessary for the remaining three patients with less serious lesions. Five of the six patients ultimately recovered their pre-operative neurological status apart from the primary diseases. Factors inducing such haemorrhages seem likely to include displacement of the cerebellum by reduced CSF pressure during and after operations, and stretching and tearing of the veins and venules in the sulci of the tentorial surface of the cerebellum. Consideration should therefore be given to the maintenance of an appropriate CSF pressure during operation; this is particularly important in elderly patients and those with an atrophied cerebral cortex.     

Posterior fossa decompression for Chiari I deformity, including resection of the cerebellar tonsils

This is an analysis of 19 consecutive cases of symptomatic patients with Chiari I deformities, undertaken to evaluate the long-term effect of posterior fossa decompression and duraplasty, assessed by postoperative imaging. Sixteen of the patients had syringomyelia and three had foramen magnum syndromes without a syrinx. Eighteen patients underwent posterior fossa craniectomy, subpial resection of the cerebellar tonsils, and duraplasty. Four patients were 16 years of age or younger. One of the children with syringomyelia had a posterior fossa decompression without resection of the tonsils. In the 15 patients with syringomyelia whose surgery included resection of the tonsils, the syrinx was reduced or resolved in 14. The patient whose syrinx did not change was a child with a lumbosacral lipoma. Three patients had syndromes of the foramen magnum without a syrinx, and of these only a patient with prior chemical and bacterial meningitis caused by a lumboureteral shunt failed to improve dramatically. When our patients are combined with 40 in the literature treated by decompression and duraplasty, 51 of 55 patients had reduction or resolution of the syrinx. Although it does not clearly affect the result, resection of the tonsils can be done safely.     

Neuroma of the spinal accessory nerve disclosed by a subarachnoid hemorrhage: case report

OBJECTIVE AND IMPORTANCE: Neuroma of the 11th nerve disclosed by subarachnoid bleeding is a very rare condition. Clinical diagnosis is almost impossible, but previous episodes of muscle spasm and mild signs of subarachnoid hemorrhage with a hematoma in the cisterna magna should suggest magnetic resonance imaging as well as angiography. CLINICAL PRESENTATION: We present a case of an 11th nerve neuroma disclosed by subarachnoid bleeding. Previous episodes of muscle spasm and neck pain treated with nonsteroid anti-inflammatory drugs had been overlooked, preventing the neuroma from being diagnosed at that time. The computed tomographic scan showed an intracisternal hematoma spreading into the subarachnoid space. The hematoma appeared heterogeneous on the magnetic resonance image, and a tumor mass growing into the cisterna magna against the brain stem was also revealed. INTERVENTION: The tumor was totally removed by a suboccipital craniectomy and C1 laminectomy. It originated from the spinal root of the 11th nerve, from which it was able to be dissected without damage to the nerve. CONCLUSION: To our knowledge, this is the first reported case of an 11th nerve neuroma disclosed by a subarachnoid hemorrhage. Furthermore, this is the seventh documented case of an 11th nerve neuroma developing in the cisterna magna. We emphasize the importance of a high index of suspicion for the rare instances of hematic density limited to the cisterna magna, especially if associated with recurring episodes of localized neck pain and muscle spasm treated with nonsteroid anti-inflammatory drugs.     

Diffuse cerebral artery vasospasm following total resection of posterior fossa meningioma: a case report]

Diffuse cerebral artery vasospasm following brain tumor resection is a rare complication. The authors reported a case of symptomatic diffuse cerebral artery vasospasm of early phase following resection of a left posterior fossa meningioma. A 50-year-old female patient was admitted to our hospital complaining of headache. No neurological deficits were detected at the time of admission. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a large mass in the left posterior fossa. Cerebral angiography demonstrated mildly diffuse stenosis of the bilateral internal carotid artery. The tumor was resected totally. CT after operation showed a small amount of subarachnoid hematoma in the superior aspect of the cerebellum. Pathological specimen of the tumor showed fibrous meningioma. One day after this radical operation, the patient was found to have weakness in her left leg. Then she developed left hemiparesis, weakness in the right leg and left homonymous hemianopsia. MRI showed ischemic lesions in the bilateral parietal and the occipital lobe. Angiography demonstrated diffuse severe vasospasm throughout the whole cerebral artery. Ten days after the operation, angiographical findings were improved. This case indicates that vasospasm may occur even after resection of brain tumors which are localized outside the suprasellar area.     

Surgical management of spinal cord compression from plexiform neurofibromas in patients with neurofibromatosis 1

OBJECTIVE: Plexiform neurofibromas with sizable intraspinal extensions and resultant spinal cord compromise pose challenging management problems, because these lesions may involve multiple nerves and engulf adjacent vascular and visceral structures. In this report, we review our experience with the surgical treatment of these lesions. METHODS: Patients were identified by a detailed review of hospital medical records and the database of our multidisciplinary neurofibromatosis clinic. Ten patients had large plexiform neurofibromas that extended intraspinally, producing a combination of myelopathy and radiculopathy. Two patients exhibited single-level intraspinal growth, and eight showed multilevel involvement. Four patients showed bilateral plexiform neurofibromatous growth intraspinally, with "hourglass" compression of the spinal cord. Operative approaches and outcomes were reviewed in detail. RESULTS: Gross total resection of the symptomatic intraspinal tumor component was achieved for nine patients. The management of the extraspinal component was individualized, depending on the pattern and extent of involvement of the surrounding structures. Nine patients experienced complete recovery of neurological function postoperatively; the remaining patient demonstrated significant functional improvement. With a median follow-up period of 4 years, only one patient has developed recurrent intraspinal compression, in this case from tumor involvement by the same plexiform lesion at a lower spinal level. Two patients treated early in the series using standard laminectomy approaches developed significant kyphotic deformities, necessitating subsequent fusion. Based on these initial results, osteoplastic laminotomy techniques were used in the last five cases, allowing anatomic reconstruction of the involved levels; none of these latter patients has developed significant kyphosis, with a median follow-up period of 3 years. CONCLUSION: Radical resection of intraspinal tumor components in patients with neurofibromatosis 1 and large plexiform neurofibromas can help to preserve excellent neurological function. Technical factors in the management of these lesions are presented.     

Serial MR in gene therapy for recurrent glioblastoma: initial experience and work in progress

PURPOSE: To describe the MR imaging findings in a pilot study evaluating gene therapy for treatment of patients with recurrent glioblastoma. METHODS: Serial MR examinations were evaluated retrospectively in patients treated with gene therapy that included a retroviral vector containing the herpes simplex virus thymidine kinase gene and intravenous ganciclovir. Images were obtained after tumor resection and after each cycle of treatment, at approximately 40-day intervals. The volume of enhancing tissue was measured on serial MR images. RESULTS: Eleven patients with recurrent glioblastoma were entered into the clinical trial of gene therapy and seven patients completed at least two cycles of treatment. Of these seven, three patients had an early (between 40 and 80 days) increase in the volume of enhancing tissue followed by a decrease or plateau in enhancing tissue volume. A fourth patient had a stable volume of enhancing tissue for 132 days. The remaining three patients had continuous increases in volume of enhancement on all subsequent MR examinations. CONCLUSION: Although animal data show striking tumor regression in response to similar gene therapy, only limited regression was observed among the seven patients we studied. The transient increases in enhancement seen in three of seven patients might reflect an inflammatory response to local injection of the viral vector.     

The insulin-like growth factor I receptor: a key to tumor growth?

We report the case of a hemophiliac in whom developed an unusual site of intracranial bleeding, a subdural hematoma that extended in the posterior fossa anteriorly from the clivus into the upper spinal subdural space. The hematoma was delayed in onset and was fatal. We review the current management recommendations for hemophiliac patients with head injury and the clinical presentation of intracranial bleeding in hemophiliacs. The necessity for Factor VIII replacement and serial computed tomography scans is emphasized.     

Diagnostic and surgical management of spinal dural arteriovenous fistulas

OBJECTIVE: A retrospective review was conducted to compare magnetic resonance (MR) and conventional spinal angiographic images and to investigate the outcome of our treatment protocol for patients with spinal dural arteriovenous fistulas (DAVFs). MATERIALS AND METHODS: Nine patients with a diagnosis of DAVF based on clinical myelopathy and preoperative MR imaging (MRI) and MR angiography (MRA) findings were treated at our institution by the senior author (BAG). All nine patients initially presented with progressive myelopathy. Preoperative MRI revealed T2-weighted signal abnormalities in all patients, and MRA was diagnostic in all patients. Each patient underwent a laminectomy and ligation of the arterialized draining vein. Selective spinal angiograms were used to confirm the level of fistula immediately before the surgical procedure was performed and to document complete obliteration after clip ligation of the medullary draining vein. Follow-up MRI and MRA were performed approximately 2 months postoperatively. RESULTS: MRI T2-weighted signal hyperintensity improved after surgery in all nine patients. Postoperatively, progression of motor weakness and gait difficulty was halted and some improvement was observed in all patients. No patient was neurologically normal, however. To date, there has been no clinical or MRA evidence of recurrence in any patient. CONCLUSION: Preoperative MRA and intraoperative spinal x-ray angiography present as an effective combination for diagnosing and intraoperatively confirming DAVF. Both T1-weighted enhancement and T2-weighted signal hyperintensity on MR images improved after the obliteration of the DAVFs and correlated with clinical improvement in all nine patients. MRA provides adequate visualization and localization of spinal DAVFs and may serve as a useful noninvasive tool for diagnosing and following patients with spinal DAVFs in the future.     

MR imaging in pretruncal nonaneurysmal subarachnoid hemorrhage: is it worthwhile?

BACKGROUND and PURPOSE: The cause of pretruncal (perimesencephalic) nonaneurysmal subarachnoid hemorrhage is not known. MRI of the brain or spine is often performed to exclude any other vascular abnormalities. Its diagnostic value is not known. METHODS: We used MR imaging of the brain with routine sequences, gadolinium enhancement, and additional thin T1-weighted axial sections following a triple dose of contrast. RESULTS: We performed MR imaging of the brain in 18 patients with a pretruncal nonaneurysmal subarachnoid hemorrhage. The focal nature of the subarachnoid hemorrhage exclusively in front of the brain stem was confirmed in 14 patients studied within 7 days of the ictus. No vascular abnormalities were found in 17 cases, including 14 patients with gadolinium enhancement. An incidental capillary telangiectasia was found in 1 patient. Fluid-attenuated inverse recovery MR additionally documented blood in the sulci due to cerebrospinal fluid recirculation of blood. Five patients underwent MR imaging of the spine, and no arteriovenous malformations were found. CONCLUSIONS: MR imaging did not reveal a source of pretruncal subarachnoid hemorrhage. The cost of MR imaging probably outweighs the benefit in the evaluation of this variant of subarachnoid hemorrhage.     

Emergency magnetic resonance of the brain

We will review the role of magnetic resonance (MR) in assessment of patients with acute neurological abnormalities. The major stumbling block to the use of MR in these patients is the belief that MR is insensitive to hyperacute (<12 h) intracranial hemorrhage and acute subarachnoid hemorrhage (SAH). Hyperacute hemorrhage has characteristic features on MR. Hematomas are iso-to hyperintense on T1-weighted and hyperintense on T2-weighted images. Gradient-echo scans that reveal characteristic peripheral hypointensity are critical to the detection and delineation of hyperacute hematomas. Use of fast fluid-attenuated inversion recovery (FLAIR) sequences has made it possible to detect SAH on MR with a sensitivity that is equal to or greater than computed tomography (CT). SAH produces dramatic hyperintensity in the normally hypointense cerebrospinal fluid on FLAIR. MR has proven useful in the detection of hypertensive encephalopathy and venous thrombosis. These entities can be difficult to diagnose on CT, and in both, early treatment can dramatically improve prognosis. The same is true for acute intracranial infections such as pyogenic abscess, subdural empyema, and herpes simplex encephalitis. MR improves diagnostic accuracy, resulting in more rapid institution of appropriate treatment and improved outcome.     

Posterior fossa decompression without duraplasty in infants and young children for treatment of Chiari malformation and achondroplasia

Some children with Chiari malformation and achondroplasia require posterior fossa decompression that typically includes expansion of the dural tube with duraplasty. Infants and young children, however, may have a more distensible dura mater than do older patients. Furthermore, the structures that compress the hindbrain of young patients may be the bone and abnormally thickened atlantooccipital membrane, i.e., dural band, rather than the dura mater. We have treated 7 children who had Chiari malformation or achondroplasia with posterior fossa decompression without duraplasty. All children were symptomatic; 3 had Chiari-I malformations, 2 Chiari-II malformations, and 2 achondroplasia. The age range was 3 months to 2.5 years (mean 15.1 months). The exent of tonsillar herniation and other hindbrain anomalies was assessed on preoperative magnetic resonance imaging. The infants with Chiari-II malformations underwent cervical laminectomies, whereas the other young children with Chiari-I malformations or achondroplasia underwent suboccipital craniectomy as well as cervical laminectomy. In Chiari malformation, the dural band was divided; in achondroplasia, there was no identifiable dural band. Following bony decompression and division of the identifiable dural band, immediate expansion of the stenotic region with visible cerebrospinal fluid space posterior to the neural elements could be ascertained by intraoperative ultrasonography. During a follow-up period ranging from 4.5 months to 4 years (mean 22 months), all patients made improvements in their symptoms, 3 having complete resolution of their symptoms. This preliminary experience indicates that in children 2 years of age or younger, posterior fossa bony decompression without duraplasty can be effective treatment for Chiari malformations or achondroplasia.