Foramen magnum decompression for syringomyelia associated with basilar impression and Chiari I malformation--report of three cases.

Anterior or posterior decompression of the foramen magnum was performed in three patients with syringomyelia associated with basilar impression and Chiari I malformation. The operative results were evaluated using the pre- and postoperative magnetic resonance (MR) images. Two patients with combined anterior and posterior cervicomedullary compression due to basilar impression and tonsillar descent received suboccipital craniectomy, upper cervical laminectomy, and dural plasty without any intradural manipulations via the posterior approach. One patient with prominent anterior cervicomedullary compression due to basilar impression and a sharp clivoaxial angle was operated on by the transoral anterior approach. Postoperatively, all patients showed a sustained shrinkage of the syrinx and rounding of the flattened cerebellar tonsils. Two patients showed upward movement of the herniated tonsils. All patients had improved symptoms during 2-4 years follow-up. Treatment of syringomyelia associated with basilar impression and Chiari I malformation requires more efficient decompressive procedures at the foramen magnum based on neurological and MR findings.     

Circumferential decompression of the foramen magnum for the treatment of syringomyelia associated with basilar invagination

Posterior fossa decompression utilizing suboccipital craniectomy and duraplasty remains the standard surgical treatment for Chiari-associated syringomyelia. In the presence of basilar invagination, anterior decompression, typically transoral odontoidectomy, or posterior decompression may be performed. We report two cases in which anterior and posterior (circumferential) decompression of the foramen magnum was used to treat cervical syringomyelia successfully. These cases demonstrate that circumferential decompression of the foramen magnum may be necessary in some cases of cervical syringomyelia associated with basilar invagination and Chiari malformation.     

Chiari type I malformations in adults: a morphometric analysis of the posterior cranial fossa

OBJECTIVE: Chiari type I malformation (CMI) is a congenital disorder characterized by caudal displacement of the cerebellar tonsils through the foramen magnum into the spinal canal. Recent studies suggest that overcrowding in the posterior cranial fossa (PCF) because of underdeveloped bony structures in the intrauterine life is the main cause of this malformation. For this reason, the authors want to contribute to the current literature, which focuses on bone abnormalities in the PCF in patients with CMIs. METHODS: We examined a retrospective cohort of 60 adult patients with CMIs, and multiple measurements were made on magnetic resonance imaging. The results were compared to 30 healthy adult control subjects. Mann-Whitney U test was used as a statistical method. RESULTS: All measurements except mean anteroposterior diameter of the foramen magnum were reduced in patients compared to control. An increase in the anteroposterior mid-sagittal distance of the foramen magnum in patients reached statistically significant difference compared to control. All patients had tonsillar herniation at least 5 mm below the plane of the foramen magnum. Chiari type I malformation in this study was associated with syringomyelia in 46 patients. CONCLUSION: This study with a limited number of patients suggests that the bony components of the PCF are not developed fully, supporting the current concept that CMI is a disorder of the para-axial mesoderm.     

Chiari I malformation associated with ventral compression and instability: one-stage posterior decompression and fusion with a new instrumentation technique

OBJECTIVE AND IMPORTANCE: We describe an alternative surgical technique for treatment of Chiari I malformation associated with ventral compression and instability of the region. An expansive suboccipital cranioplasty and a rigid occipitocervical fixation are performed in one stage. METHODS: The occipitocervical fixation is performed by use of metal rods fixed on the cranial side by screws inserted into the diploic layer of occipital bone and on the caudal side by screws inserted into the pedicle of the axis or in a transarticular fashion into the lateral masses of axis and atlas vertebra. A large piece of autologous bone is placed in the region between the rostral edge of cranial decompression and the axis, with the aim of achieving both expansive suboccipital cranioplasty and occipitocervical fusion. RESULTS: We performed this procedure in two patients with Chiari I malformation associated with basilar invagination and occipitalization of the atlas. Postoperatively, decompression of the brainstem and restoration of normal cerebrospinal fluid flow at the craniovertebral junction were confirmed radiologically, and the patients were relieved of their symptoms. At 1 and 3 years of follow-up, respectively, solid bone fusion was observed between the occipital bone and axis in both patients. CONCLUSION: Simultaneous posterior decompression and occipitocervical fixation with an alternative instrumentation technique is discussed. The procedure can be performed regardless of the size of suboccipital craniectomy. Screw insertion into the diploic layer of the occipital bone has not been described previously.     

Transverse Microincisions of the Outer Layer of the Dura mater Combined with Foramen Magnum Decompression as Treatment for Syringomyelia with Chiari I Malformation

Summary Numerous surgical procedures have been proposed for treatment of syringomyelia associated with Chiari I malformation, but the optimal treatment has not yet been uniformly standardised. The main aim of the surgical treatment of syringomyelia/Chiari I complex is directed toward restoration of physiological cerebrospinal fluid dynamic at the craniovertebral junction. We report the surgical results of eight patients, affected by syringomyelia and Chiari I malformation, age range from 18 to 62 years, treated by bony foramen magnum decompression combined with transverse microincisions of the outer layer of the dura mater. In an average postoperative follow-up period of two years neurological symptoms and signs improved in seven patients. Postoperative Magnetic Resonance showed a decrease in size of the syrinx in seven patients. These results suggest that foramen magnum decompression combined with transverse microincisions of the outer layer of the dura 1) is an effective and safe treatment option for syringomyelia and Chiari I malformation, 2) corrects the circulatory disturbances of cerebrospinal fluid dynamic, 3) leads to a decrease in size of the syrinx and to a significant improvement in neurological signs and symptoms, 4) avoids complications of intradural approaches and syringosubarachnoid shunting.     

Management of cerebellar ptosis following craniovertebral decompression for Chiari I malformation

OBJECT: In this report the authors review their experience in the treatment of seven patients with symptomatic cerebellar ptosis following craniovertebral decompression (CVD) for Chiari I malformation. METHODS: The mean age of the patients was 37 years and the average amount of time between the initial suboccipital craniectomy and evaluation for cerebellar ptosis was 6.8 years. Five patients presented primarily with intractable headache and the remaining two patients with neurological deficits caused by recurrent syringomyelia. Three different surgical modalities were used to treat these patients: ventriculoperitoneal shunt placement (one patient), syringoperitoneal shunt placement (two patients), and partial suboccipital cranioplasty with or without intradural exploration (four patients). The mean follow-up period was 51 months. The three patients who underwent shunt placement procedures experienced poor results, with no evidence of symptom relief and continued neurological deterioration. In contrast, all four patients who underwent cranioplasty experienced good or excellent clinical outcomes. Postoperative magnetic resonance imaging studies revealed a reduction in the size of the syrinx cavity in patients who simultaneously underwent intradural exploration. CONCLUSIONS: The emergence of symptomatic cerebellar ptosis following CVD for Chiari I malformation is primarily caused when the suboccipital craniectomy is too large for the specific patient. The cerebellar ptosis usually presents with severe headache and/or neurological deficit due to persistent or recurrent syringomyelia. Partial suboccipital cranioplasty, with or without intradural exploration, is effective in treating this condition.     

Surgical treatment of syringomyelia. Selection of surgical procedures

The surgical approach to syringomyelia is controversial. In this study, the authors evaluated the results of various operative procedures applied in 31 patients with syringomyelia. Syringomyelia was associated with Chiari malformation in 17 cases, with spinal adhesive arachnoiditis in nine, with trauma in three, and with epidural arachnoid cyst in one. One case was idiopathic. A total of 38 operations were performed. Syringosubarachnoid shunting was applied in 17 patients, syringoperitoneal shunting in 11, terminal syringostomy in three, ventriculoperitoneal shunting in three, lumboperitoneal shunting in two, foramen magnum decompression (suboccipital craniectomy plus upper cervical laminectomy) and terminal syringostomy in one, and foramen magnum decompression with syringosubarachnoid shunting in one. The postoperative follow-up period ranged from 2 to 55 months (average, 26 months). Of the 31 patients, 23 showed neurological improvement, five were unchanged, and three deteriorated. Among the last three, one patient with Chiari malformation developed shunt malfunction due to arachnoiditis after syringosubarachnoid shunting. In two patients with syringomyelia secondary to adhesive arachnoiditis, the spinal cord was damaged by extensive separation of the arachnoid membrane at surgery. On the basis of the results in these 31 cases, the authors conclude that syringosubarachnoid shunting is effective for syringomyelia associated with Chiari malformation if syringomyelia is responsible for the clinical symptoms. Post-traumatic syringomyelia and syringomyelia secondary to adhesive arachnoiditis should be treated by syringoperitoneal shunting. If hydrocephalus is present, ventriculoperitoneal shunting is indicated. Finally, terminal syringostomy is no more effective than syringosubarachnoid or syringoperitoneal shunting.     

Chiari malformation (type 1) with regeneration of removed C1 lamina after foramen magnum decompression: a case report

We present the case of a 20-year-old female who underwent foramen magnum decompression and laminectomy of C1-C3 as well as incision of only the outer layer of the dura, for her symptomatic Chiari malformation (type 1) with syringomyelia, at the age of 9 years. She required additional surgery with removal of regenerated bone and dural plasty for the remaining and recurrent stenosis. The remaining stenosis may have been caused by the use of a technique without dural plasty and insufficient decompression of the bony structure. Further, the regeneration of C1 lamina could have been responsible for the recurrent stenosis. Her symptoms, which included gait disturbance, hypesthesia, excessive sweating, and nocturnal enuresis, manifested themselves when she was at the age of 2 years and progressed since that time. These symptoms didn't improve after the first surgery. However, after the second surgery, the gait disturbance and nocturnal enuresis were partially resolved. It is rare for new bone generation to necessitate reoperation. However, it should be noticed that careful follow-up is important after decompressive surgery for Chiari malformation in young patients.     

Foramen magnum decompression for the treatment of Arnold Chiari malformation type I with associated syringomyelia in an elderly patient

STUDY DESIGN: Report of a rare case of an elderly patient with late onset of Arnold Chiari malformation type I with associated syringomyelia that was successfully treated with foramen magnum decompression. OBJECTIVE: To report this rare case along with a literature review. SETTING: Gifu, Japan. METHODS: A 69-year-old woman with a 4-year history of dull pain in her right arm was referred to the clinic. After physical and radiographical examinations, she was diagnosed with Arnold Chiari malformation type I with associated syringomyelia. A foramen magnum decompression by the removal of the outer layer of the dura mater was performed. RESULTS: At 2 years postoperatively, MRI revealed a decrease in the size of the syringomyelia. Her symptoms had also remarkably improved. CONCLUSIONS: A rare case of symptomatic Arnold Chiari malformation type I with associated syringomyelia in an elderly woman was successfully treated with foramen magnum decompression by the removal of the outer layer of the dura mater.     

Surgery for Syringomyelia: An Analysis Based on 163 Surgical Cases

Summary ? Object. The authors analyzed the cases of 163 patients with syringomyelia to assess the appropriate surgical procedure. Methods. Depending on the aetiological factors and treatment considerations the series was classified into three groups. Group I were cases where there was no definite demonstrable aetiological factor; Group II cases had basilar invagination and/or Chiari malformation; and Group III consisted of cases where the syrinx was secondary to an obvious aetiology, such as a mass lesion either in the posterior cranial fossa or in the spine or a severe kyphotic spinal deformity. Post-traumatic syringomyelia and syrinx in association with spina bifida were not studied. Conclusions. We concluded that for Group I cases syringosubarachnoid shunting is the ideal form of treatment. In Group II cases foramen magnum bony decompression is satisfactory and physiological. Good results were obtained even in cases where either a foramen magnum decompression alone or in combination with a syringo-subarachnoid shunt was done. Only syringosubarachnoid shunt (without a foramen magnum decompression) in Group II cases was found to produce poor outcome. Group III cases should be treated for the primary aetiological problem. Only syrinx drainage procedure without treatment of aetiology in these cases produced poor results. It was observed that clinical outcome rather than radiological improvement is the reliable indicator of the surgical result.     

Elucidating the pathophysiology of syringomyelia.

OBJECT: Syringomyelia causes progressive myelopathy. Most patients with syringomyelia have a Chiari I malformation of the cerebellar tonsils. Determination of the pathophysiological mechanisms underlying the progression of syringomyelia associated with the Chiari I malformation should improve strategies to halt progression of myelopathy. METHODS: The authors prospectively studied 20 adult patients with both Chiari I malformation and symptomatic syringomyelia. Testing before surgery included the following: clinical examination; evaluation of anatomy by using T1-weighted magnetic resonance (MR) imaging; evaluation of the syrinx and cerebrospinal fluid (CSF) velocity and flow by using phase-contrast cine MR imaging; and evaluation of lumbar and cervical subarachnoid pressure at rest, during the Valsalva maneuver, during jugular compression, and following removal of CSF (CSF compliance measurement). During surgery, cardiac-gated ultrasonography and pressure measurements were obtained from the intracranial, cervical subarachnoid, and lumbar intrathecal spaces and syrinx. Six months after surgery, clinical examinations, MR imaging studies, and CSF pressure recordings were repeated. Clinical examinations and MR imaging studies were repeated annually. For comparison, 18 healthy volunteers underwent T1-weighted MR imaging, cine MR imaging, and cervical and lumbar subarachnoid pressure testing. Compared with healthy volunteers, before surgery, the patients had decreased anteroposterior diameters of the ventral and dorsal CSF spaces at the foramen magnum. In patients, CSF velocity at the foramen magnum was increased, but CSF flow was reduced. Transmission of intracranial pressure across the foramen magnum to the spinal subarachnoid space in response to jugular compression was partially obstructed. Spinal CSF compliance was reduced, whereas cervical subarachnoid pressure and pulse pressure were increased. Syrinx fluid flowed inferiorly during systole and superiorly during diastole on cine MR imaging. At surgery, the cerebellar tonsils abruptly descended during systole and ascended during diastole, and the upper pole of the syrinx contracted in a manner synchronous with tonsillar descent and with the peak systolic cervical subarachnoid pressure wave. Following surgery, the diameter of the CSF passages at the foramen magnum increased compared with preoperative values, and the maximum flow rate of CSF across the foramen magnum during systole increased. Transmission of pressure across the foramen magnum to the spinal subarachnoid space in response to jugular compression was normal and cervical subarachnoid mean pressure and pulse pressure decreased to normal. The maximum syrinx diameter decreased on MR imaging in all patients. Cine MR imaging documented reduced velocity and flow of the syrinx fluid. Clinical symptoms and signs improved or remained stable in all patients, and the tonsils resumed a normal shape. CONCLUSIONS: The progression of syringomyelia associated with Chiari I malformation is produced by the action of the cerebellar tonsils, which partially occlude the subarachnoid space at the foramen magnum and act as a piston on the partially enclosed spinal subarachnoid space. This creates enlarged cervical subarachnoid pressure waves that compress the spinal cord from without, not from within, and propagate syrinx fluid caudally with each heartbeat, which leads to syrinx progression. The disappearance of the abnormal shape and position of the tonsils after simple decompressive extraarachnoidal surgery suggests that the Chiari I malformation of the cerebellar tonsils is acquired, not congenital. Surgery limited to suboccipital craniectomy, C-I laminectomy, and duraplasty eliminates this mechanism and eliminates syringomyelia and its progression without the risk of more invasive procedures.     

Anterior atlas fracture following suboccipital decompression for Chiari I malformation. Report of two cases

Chiari I malformation, a congenital disorder involving downward displacement of the cerebellar tonsils through the foramen magnum, is often treated surgically by performing suboccipital craniectomy and C-1 laminectomy. The authors report two cases in which fracture of the anterior atlantal arch occurred during the postoperative period following Chiari I decompression and C-1 laminectomy causing significant neck pain. The findings indicate that interruption of the integrity of the posterior arch of C-1, iatrogenically or otherwise, confers increased risk of anterior arch fracture. A C-1 fracture should therefore be considered in the differential diagnosis of posterior cervical pain in patients who have previously undergone decompression for Chiari I malformation.     

Syringo-subarachnoid shunt for syringomyelia associated with Chiari malformation (type 1)

Summary The authors report the surgical results of 28 patients with syringomyelia associated with Chiari malformation (type 1). 28 patients underwent 34 operative procedures. Syringo-subarachnoid shunt was performed in 28 patients, foramen magnum decompression with syringo-subarachnoid shunt in three, ventriculo-peritoneal shunt in one, terminal syringostomy in one, and foramen magnum decompression with terminal syringostomy in one. In an average postoperative follow-up period of 3 years and 9 months ranging from one year to 7 years and one month, neurological symptoms and signs improved in 24 out of 28 patients (82%). Some improvement was noted in sensory deficit and motor weakness. In 3 patients, the symptoms did not change. In 3 patients whose symptoms were unchanged, preoperative studies demonstrated atrophy of the spinal cord, in which irreversible changes were shown. The symptoms deteriorated in one patient. In one patient whose symptoms increased 3 months after syringo-subarachnoid shunt, shunt insufficiency due to postoperative adhesive arachnoiditis was responsible for neurological deterioration.The authors propose that syringo-subarachnoid shunt is effective as a surgical procedure for syringomyelia associated with Chiari malformation (type 1) if the patient does not have symptoms due to Chiari malformation or has only mild signs and symptoms which do not require foramen magnum decompression, such as nystagmus or atrophy of sternocleidomastoid muscle.     

Spontaneous resolution of Chiari I malformation and syringomyelia: case report and review of the literature

OBJECTIVE AND IMPORTANCE: Indications for surgery and the surgical technique of foramen magnum decompression for patients with Chiari I malformation and syringomyelia are controversial issues. This case report supports the view that observation may be adequate for patients without progressive symptoms or with mild clinical symptoms. CLINICAL PRESENTATION: A 37-year-old woman presented with a 3-month history of burning dysesthesias and hypesthesia in her right arm. A neurological examination revealed hypesthesia in the right trigeminal distribution. A magnetic resonance imaging scan revealed a Chiari I malformation with syringomyelia between C2 and T2. No hydrocephalus was observed. CLINICAL COURSE: Because the patient's symptoms regressed spontaneously, surgery was not performed. Thirty-two months after her initial examination, the patient was asymptomatic. A second magnetic resonance imaging scan was obtained, which demonstrated complete spontaneous resolution of the Chiari I malformation and syringomyelia. CONCLUSION: We attribute the regression of the patient's symptoms to spontaneous recanalization of cerebrospinal fluid pathways at the foramen magnum, which most likely was due to rupture of the arachnoid membranes that had obstructed cerebrospinal fluid flow.     

Hiccups attributable to syringobulbia and/or syringomyelia associated with a Chiari I malformation: case report

OBJECTIVE AND IMPORTANCE: Approximately 20 to 50% of patients with syringomyelia associated with Chiari malformations exhibit cranial nerve or cerebellar symptoms. However, hiccups represent a rare clinical manifestation of this disorder. We report a case of intractable hiccups resulting from syringobulbia associated with a Chiari I malformation, which was successfully treated with foramen magnum decompression. CLINICAL PRESENTATION: We report the case of a patient who presented with syringomyelia and syringobulbia associated with a Chiari I malformation, manifested as intractable hiccups and neurological deficits. Magnetic resonance imaging scans demonstrated syringobulbia in the dorsal medullary region and a large cervical syrinx from C2 to C6-C7, associated with a Chiari I malformation. INTERVENTION: Foramen magnum decompression and a C1 laminectomy were performed. One month later, the intractable hiccups disappeared and the neurological symptoms demonstrated improvement. CONCLUSION: Postoperative magnetic resonance imaging scans demonstrated enlargement of the subarachnoid space in the posterior fossa and disappearance of the syringobulbia. There has been no recurrence of intractable hiccups and syringobulbia in 6 months after surgery. Magnetic resonance imaging of the brainstem is an important diagnostic procedure for intractable hiccups, because syringobulbia associated with a Chiari malformation represents a surgically treatable disorder, although the incidence is low.     

Symptomatic Chiari malformation in adults: a new classification based on magnetic resonance imaging with clinical and prognostic significance

Thirty-five consecutive adults with Chiari malformation and progressive symptoms underwent surgical treatment at a single institution over a 3-year period. All patients underwent magnetic resonance imaging scan before and after surgery. Images of the craniovertebral junction confirmed tonsillar herniation in all cases and allowed the definition of two anatomically distinct categories of the Chiari malformation in this age group. Twenty of the 35 patients had concomitant syringomyelia and were classified as Type A. The remaining 15 patients had evidence of frank herniation of the brain stem below the foramen magnum without evidence of syringomyelia and were labeled Type B. Type A patients had a predominant central cord symptomatology; Type B patients exhibited signs and symptoms of brain stem or cerebellar compression. The principal surgical procedure consisted of decompression of the foramen magnum, opening of the fourth ventricular outlet, and plugging of the obex. Significant improvement in preoperative symptoms and signs was observed in 9 of the 20 patients (45%) with syringomyelia (Type A), as compared to 13 of the 15 patients (87%) without syringomyelia (Type B). Postoperative reduction in syrinx volume was observed in 11 of the 20 patients with syringomyelia, including all 9 patients with excellent results. Magnetic resonance imaging has allowed a classification of the adult Chiari malformation in adults based on objective anatomic criteria, with clinical and prognostic relevance. The presence of syringomyelia implies a less favorable response to surgical intervention.     

Neuraxial analgesia during labor in a patient with Arnold-Chiari type I malformation and syringomyelia

Chiari type I malformation is a caudal displacement of the cerebellum with tonsillar herniation through the foramen magnum, frequently associated with syringomyelia, a syndrome characterized by cyst-like cavities in the spinal cord; each of the conditions leads to characteristic neurologic abnormalities. Pregnant patients with these types of malformation are considered to have an increased risk of brainstem compression and/or progression of the disease during labor. We present the case of a patient in labor with a diagnosis of syringomyelia associated with Chiari type I malformation and describe the anesthetic management. The patient revealed during labor that she had syringomyelia associated with Chiari type I malformation, after having made no mention of it in previous history taking. Finally, we review the pathology observed in these patients.     

Spontaneous resolution of syringomyelia without Chiari malformation

A 30-year-old woman presented with a cervical syrinx manifesting as hemihypesthesia. Neuroimaging found no evidence of Chiari malformation or tight cisterna magna. Serial magnetic resonance imaging studies over a 6-year period demonstrated spontaneous and complete resolution of the syrinx accompanied by an asymptomatic clinical course. The natural history of syringomyelia is highly unpredictable. The outcome of surgical treatment for patients with syringomyelia is not always satisfactory, so the indications for surgery are controversial. Spontaneous resolution of syringomyelia unrelated with foramen magnum lesion has various causes. Close follow up of the patient is necessary to monitor for recurrence.     

Malformations of the craniocervical junction (chiari type I and syringomyelia: classification,diagnosis and treatment)

Chiari disease (or malformation) is in general a congenital condition characterized by an anatomic defect of the base of the skull, in which the cerebellum and brain stem herniate through the foramen magnum into the cervical spinal canal. The onset of Chiari syndrome symptoms usually occurs in the second or third decade (age 25 to 45 years). Symptoms may vary between periods of exacerbation and remission. The diagnosis of Chiari type I malformation in patients with or without symptoms is established with neuroimaging techniques. The most effective therapy for patients with Chiari type I malformation/syringomyelia is surgical decompression of the foramen magnum, however there are non-surgical therapy to relieve neurophatic pain: either pharmacological and non-pharmacological. Pharmacological therapy use drugs that act on different components of pain. Non-pharmacological therapies are primarly based on spinal or peripheral electrical stimulation.