Asymmetry of tonsillar ectopia,syringomyelia and clinical manifestations in adult Chiari I malformation

Background

The asymmetry of tonsillar ectopia, syringomyelia, and clinical manifestations, and their correlations in adult Chiari I malformation (CIM) are seldom discussed.

Methods

Clinical and imaging data of 104 consecutive adult patients with CIM and syringomyelia were retrospectively reviewed. A method was devised to quantify tonsillar and syrinx asymmetry. Correlations between the asymmetrically displaced cerebellar tonsils, the side of the syrinx, clinical presentations, and the curve direction of scoliosis were investigated.

Results

Tonsillar ectopia was left dominant in 46 patients (44.2 %), right dominant in 49 (47.1 %), and symmetrical in nine (8.7 %). The syrinx was left deviated in 44 patients (42.3 %), right deviated in 48 (46.2 %), and centrally located in 12 (11.5 %). A significant correlation was observed between the side of tonsillar herniation and the side of the syrinx (p?<?0.001), and also between the descending ratio of tonsillar herniation and the deviation ratio of the syrinx (p?<?0.001). The main side the of clinical presentations showed significant correlation with the dominant side of tonsillar herniation (p?=?0.009) and the side of syrinx deviation (p?=?0.012). In the 49 patients (47.1 %) with associated scoliosis, the curve direction was significantly related to not only the dominant side of tonsillar ectopia (p?=?0.0,28) but also the deviated side of the syrinx (p?=?0.044). Moreover, the curve magnitude was significantly correlated with the distance of the tonsillar herniation (p?=?0.001).

Conclusions

In adult CIM, most tonsillar herniations are asymmetrical and most syringomyelia is eccentrical. We speculate that the dominant side of tonsillar herniation determines the side of syrinx deviation, which in turn determines the main side of clinical presentations and the convex side of scoliosis. Our results suggest that the more the descended tonsil tilts to one side, the more the syrinx tilts to the same side.     

Symptomatic syringomyelia secondary to clinically obscure infratentorial tumour

The formation of a cervical spinal cord syrinx as a result of an infratentorial mass, even though uncommon, has been reported in international literature. In such cases, syringomyelia is usually asymptomatic, while the tumour-related symptoms and signs predominate. We report a patient with a posterior fossa tumour and secondary syringomyelia. In this patient, syringomyelia symptoms and signs were present, and a cervical spine Magnetic Resonance Imaging (MRI) showed a large cervical syrinx. A more careful clinical examination though, revealed a sub-clinical posterior fossa syndrome and brain MRI revealed a large infratentorial meningioma. A posterior fossa craniotomy was performed, followed by complete tumour resection and almost complete remission of the syrinx and its related symptoms. The authors discuss the role of posterior fossa tumour induced tonsillar herniation in the development of secondary syringomyelia, the mechanisms leading to syrinx formation and the conditions that must be fulfilled for that to happen.     

Retrocerebellar arachnoid cyst resulting in syringomyelia in a patient without tonsillar herniation: successful surgical treatment with reconstruction of CSF flow in the foramen magnum region

A retrocerebellar arachnoid cyst causing syringomyelia is extremely rare without tonsillar herniation. The authors present a 44-year-old woman with symptoms of foramen magnum compression and syringomyelia. Magnetic resonance imaging demonstrated a large retrocerebellar arachnoid cyst with a large cervicothoracic syrinx but no signs of tonsillar herniation or hydrocephalus. The patient underwent a foramen magnum decompression with C1 laminectomy, microsurgical fenestration of the cyst, and duraplasty. After successful reconstruction of CSF flow, the patient experienced a relief of symptoms and a significant reduction of the syrinx. The intraoperative findings support the theory of a piston mechanism in the development of syringomyelia. Additional arachnoidal adhesions may also obstruct the CSF flow around the craniocervical junction. We recommend the surgical treatment should consist of an adequate decompression of the foramen magnum, wide microsurgical arachnoidal debridement, and duraplasty with autologous grafts sutured in a watertight way.     

Resolution of Tonsillar Herniation and Cervical Syringomyelia Following Resection of a Large Petrous Meningioma: Case Report and Review of Literature

We describe a case of a large, petrous meningioma associated with tonsillar herniation and cervical syringomyelia. The patient, a 53-year-old woman, had a 6-month history of a dull, aching pain in the occipital region associated with numbness in the right C2 dermatome and left gaze evoked nystagmus. Magnetic resonance imaging (MRI) revealed a large tumor in the right posterior fossa associated with moderate supratentorial hydrocephalus. Secondary tonsillar herniation and cervical syringomyelia extending from C2 to C6 were also identified. The tumor, later confirmed to be a meningioma originating from the petrous region, was resected completely via a retrosigmoid approach. Postoperative MRI demonstrated total resolution of the tonsillar herniation and cervical syringomyelia. The radiological features, potential pathophysiological mechanisms, and treatment strategies are discussed in relation to the recent literature.     

Resolution of syringomyelia and Chiari I malformation by ventriculoatrial shunting in a patient with pseudotumor cerebri and a lumboperitoneal shunt

A sneeze caused acute left arm pain in a 36-year-old woman with a lumboperitoneal (LP) shunt that had been placed 3 years earlier for relief of headaches caused by pseudotumor cerebri. Numbness progressed up the left arm, neck, and back of the head and finally into the left face along with weakness of the hand and arm. Magnetic resonance imaging (MRI) and computed tomography revealed new tonsillar herniation and a large eccentric syrinx extending from C2 to T6. The functioning LP shunt was clamped, and a ventriculoatrial shunt was placed. Pain lessened and motor function improved slightly. MRI revealed complete resolution of the syrinx and resolution of the tonsillar herniation. Theories of syringomyelia formation, the relationship to Chiari I malformation, and the implications of this case are discussed.     

Association of asymptomatic syringomyelia with tentorial meningioma

A case of asymptomatic syringomyelia associated with tentorial meningioma is reported. A 53-year-old female was admitted to our hospital with the complaints of headache, decrease of bilateral visual acuity and gait disturbance. Neurological examination revealed no abnormality except for bilateral papilledema and left cerebellar sign. Motor and sensory systems were also intact. CT and MRI scans showed a left tentorial mass lesion, cervical syringomyelia and left tonsillar herniation. A relationship between the fourth ventricle and syringomyelia was not clearly identified. The tumor was totally removed and a histological diagnosis of fibroblastic meningioma was made. Postoperative radiological examination showed a diminishing of syringomyelia with the improved tonsillar herniation. Association of syringomyelia with brain tumor was reviewed, and its pathogenesis was discussed.     

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.     

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.     

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.     

Natural history of scoliosis in children with syringomyelia

We performed a retrospective review of 27 scoliotic patients with syringomyelia using MRI. Their mean age at the first MRI examination was 10.9 years, and at the final review 15.8 years. The mean ratio of the diameter of the syrinx to the cord on the midsagittal MRI (S/C ratio) decreased from 0.49 to 0.24; 14 patients showed a decrease of 50% or more (reduction group). In this reduction group, the cerebellar tonsillar herniation decreased from a mean of 11.3 mm to 6.0 mm, and some improvement in dissociated sensory disturbance was seen in nine of 13 patients. The scoliosis improved by 5 degrees or more in six patients in the reduction group. Our results indicate that spontaneous shrinkage of syringomyelia in children is not unusual and is associated with improvement in the tonsillar herniation, the scoliosis and the neurological deficit.     

Chiari malformation and syringomyelia in monozygotic twins: birth injury as a possible cause of syringomyelia--case report

A 26-year-old female, the elder of monozygotic twins, presented with slow progressive numbness and pain in her left arm. Magnetic resonance (MR) imaging showed syringomyelia with Chiari malformation. The patient's birth had been difficult with prolonged delivery time, breech delivery, and neonatal asphyxia. MR imaging of the patient's twin sister showed mild tonsillar ectopia, but absence of syringomyelia. This younger sister was born without problems. The patient underwent syringosubarachnoid shunt at the C5-6 level. The syrinx was collapsed promptly, and her symptoms disappeared. This case of syringomyelia with Chiari malformation in one of twins suggests that birth injury is likely to be a cause of the pathogenesis of syringomyelia.     

Spontaneous resolution of syringomyelia: report of two cases and review of the literature

OBJECTIVE AND IMPORTANCE: The natural history of syringomyelia is highly unpredictable, and some patients experience improvement or stabilization without surgery. However, the mechanisms of the formation and spontaneous resolution of syringomyelia remain controversial. This report concerns two patients with syringomyelia who demonstrated spontaneous reductions in syrinx size, accompanied by symptomatic improvement. CLINICAL PRESENTATION: One patient was a 10-year-old girl with syringomyelia associated with a tight cisterna magna and basilar impression, who demonstrated a spontaneous decrease in syrinx size, accompanied by symptomatic improvement, in 22 months. The other patient was a 39-year-old man with syringomyelia associated with a Chiari I malformation, who demonstrated a spontaneous reduction in syrinx size and neurological improvement, accompanied by elevation of the cerebellar tonsils, 6 months after diagnosis. INTERVENTION: The patients were monitored. CONCLUSION: The mechanisms of spontaneous resolution of syringomyelia, as well as the factors leading to the cerebrospinal fluid flow disturbances that cause syringomyelia, may vary. Resolution of foramen magnum lesion-related syringomyelia may be the result of spontaneous correction of the abnormal cerebrospinal fluid flow, as observed in our cases, or of cavity fluid drainage into the spinal arachnoid space because of spinal cord fissuring.     

Chiari畸形Ⅰ型患者小脑扁桃体下疝程度及脊髓空洞形态与后颅窝容积的相关性

目的:分析Chiari畸形Ⅰ型(Chiari malformation typeⅠ,CMⅠ)患者小脑扁桃体下疝程度及脊髓空洞形态与后颅窝线性容积的关系,探讨影响小脑扁桃体下疝程度的后颅窝解剖学因素。方法:2003年6月~2011年6月在我科接受治疗并符合入选标准的CMⅠ患者共59例,男34例,女25例,年龄16~20岁,平均17.9岁,Risser征5级,均有完整MRI资料(包括头枕部及全脊髓矢状面扫描图像);均无颅内占位性病变、颅骨破坏、后颅窝手术史或获得性Chiari畸形。均伴有不同形态的脊髓空洞,55例(93.2%)伴有不同程度的脊柱侧凸畸形。在MRI T1加权像正中矢状位扫描层面上评估患者的小脑扁桃体下疝程度和脊髓空洞类型;测量后颅窝斜坡长度、枕骨大孔前后径、枕骨鳞部长度、后颅窝矢状径、后颅窝高径和斜坡倾斜角。将CMⅠ患者按照小脑扁桃体下疝严重程度分为三度:Ⅰ度,小脑扁桃体下缘超过枕骨大孔水平5mm但没有到达C1后弓上缘;Ⅱ度,小脑扁桃体下缘尾向移位超过C1后弓上缘但未超过C1后弓下缘;Ⅲ度,小脑扁桃体下缘尾向移位超过C1后弓下缘。依据脊髓空洞类型分为膨胀型、念珠型、细长型和局限型四组。比较不同组间后颅窝线性容积的差异,并对相关指标进行相关性分析。结果:Ⅰ度扁桃体下疝CMⅠ患者的后颅窝斜坡长度明显大于Ⅱ、Ⅲ度扁桃体下疝CMⅠ患者(P<0.05),Ⅲ度扁桃体下疝患者的斜坡倾斜角较Ⅰ、Ⅱ度患者明显减小(P<0.05),其余指标三组间无显著性差异;CMⅠ患者的斜坡倾斜角与小脑扁桃体下疝程度之间存在显著性负相关关系(r=-0.626,P=0.005)。膨胀型脊髓空洞患者的斜坡倾斜角显著小于其他类型的脊髓空洞患者(P<0.05),其余指标各类型之间无显著性差异。结论:后颅窝斜坡短平可能是促使CMⅠ患者小脑扁桃体下疝加重的重要因素之一,同时对CMⅠ患者的脊髓空洞的形成和发展也存在影响。     

Decompression of the spinal subarachnoid space as a solution for syringomyelia without Chiari malformation

STUDY DESIGN: Review and analysis of seven cases of syringomyelia treated surgically. OBJECTIVE: To demonstrate the beneficial role of decompressive surgery for the altered cerebrospinal fluid (CSF) flow dynamics in syringomyelia not associated with Chiari I malformation. A comparison between the pre- and post-operative syrinx size and CSF flow in the subarachnoid space was made using cine-mode magnetic resonance imaging (cine-MRI) and then correlated with clinical improvement. SETTING: University Hospital, Seoul, Korea. METHODS: Conventional spinal MRI and cine-MRI were performed in the region of CSF flow obstruction preoperatively in seven patients with syringomyelia not associated with Chiari I malformation. The group consisted of one case of syrinx with post-traumatic compression fracture, one case of post-traumatic arachnoiditis, two cases of holocord syrinx associated with hydrocephalus without Chiari malformation, one case of syrinx with post-traumatic pseudomeningeal cyst, one case of post-laminectomy kyphosis-associated syringomyelia and one case of post-tuberculous arachnoiditis syringomyelia. Based on the preoperative cine-MRI, the types of surgery appropriate to correct the CSF flow obstruction were chosen: decompressive laminectomy-adhesiolysis and augmentation duraplasty in arachnoiditis cases, ventriculoperitoneal shunt for hydrocephalus, cyst extirpation in pseudomeningeal cyst and both anterior and posterior decompression-fusion in the case of post-laminectomy kyphosis. A syrinx-draining shunt operation was performed in three cases; where the syringomyelia was associated with post-traumatic compression fracture refractory to a previous decompression, where hydrocephalus was present in which the decompression by ventriculoperitoneal shunt was insufficient and where post-traumatic arachnoiditis was present in which the decompression was impossible due to diffuse adhesion. Change in syrinx size was evaluated with post-operative MRI in all seven cases and restoration of flow dynamics was evaluated with cine-MRI in three of the cases, two patients with clinical improvement and one patient with no change of clinical status, respectively. RESULTS: Four out of seven patients showed symptomatic improvement after each decompressive operation. In the remaining three cases, reconstruction of the spinal subarachnoid space was not possible due to diffuse adhesion or was not the main problem as in the patient with syrinx associated with hydrocephalus who had to undergo a shunt operation. One of these three patients showed clinical improvement after undergoing syringosubarachnoid shunt. A decrease of syrinx size was observed in only two out of the five patients who showed clinical improvement after treatment. Of these five patients, two patients underwent post-operative cine-MRI and the restoration of normal CSF flow dynamics was noted in both patients. Of the remaining two patients, one underwent post-operative cine-MRI and there was no change in the CSF flow dynamics evident. CONCLUSION: These results suggest that the restoration of CSF flow dynamics between the syrinx and the subarachnoid space by decompressive operation is more effective than simple drainage of the syrinx cavity itself in the treatment of syringomyelia without Chiari malformation.     

Reversible tonsillar prolapse and syringomyelia after embolization of a tectal arteriovenous malformation. Case report and review of the literature

The authors report the case of a 21-year-old woman who presented with headaches, frequent sensations of loss of equilibrium, and intermittent strabismus. A tectal arteriovenous malformation (AVM) was diagnosed based on magnetic resonance (MR) imaging findings. The AVM drained toward the straight sinus and was associated with a tonsillar prolapse (Chiari malformation Type I [CM-I]) and cervical syringomyelia. The tectal AVM was embolized with N-butyl cyanoacrylate, and disconnection of about 80% of the lesion was obtained. All clinical symptoms resolved after embolization, and radiosurgery was proposed to treat the malformation remnant. A control MR image confirmed the regression of the tonsillar prolapse and the disappearance of the syrinx. This report emphasizes that CM-I and syringomyelia may be acquired and related to hydrovenous disorders.     

Incidentally identified syringomyelia associated with Chiari I malformations: is early interventional surgery necessary?

OBJECTIVE: The purpose of this study was to analyze clinical data and magnetic resonance imaging (MRI) findings for patients with asymptomatic, incidentally identified syringomyelia associated with Chiari I malformations who were monitored for more than 10 years, and to clarify the natural history of these lesions. METHODS: The clinical records of nine patients who had not been surgically treated and were regularly subjected to neurological and MRI examinations were analyzed. In MRI studies, the axial diameter of the syrinx at the widest level, the longitudinal extent of the syrinx, and the extent of tonsillar herniation into the spinal canal were analyzed. As a control, MRI findings for 11 patients with symptomatic syringomyelia associated with Chiari I malformations who had been surgically treated were also analyzed, and these MRI parameters were statistically compared between the asymptomatic and symptomatic groups. RESULTS: One patient underwent surgery, because of neurological changes, 7 years after the first visit. None of the remaining patients demonstrated any neurological change during the follow-up period (11.2+/-0.7 yr), and all of them have been faring well without surgery. No statistically significant differences in MRI findings between the asymptomatic and symptomatic groups were observed. CONCLUSION: The long-term clinical courses of patients with asymptomatic, incidentally identified syringomyelia associated with Chiari I malformations were observed to be benign. MRI parameters did not provide predictable values to recommend interventional surgery. Unless changes in neurological or MRI findings are detected, early interventional surgery is not necessary.     

Magnetic resonance imaging in syringomyelia

Myelography and myelography assisted with computed tomography have been the most commonly used radiographic methods in the study of syringomyelia. These studies have never been entirely reliable in demonstrating the syrinx cavity and its relationship to other intracranial structures. During the 1st year of operation of the magnetic resonance imaging facility, the syringomyelic cavity was demonstrated in 15 patients who all had typical clinical signs and symptoms associated with syringomyelia. Nine cases were syringomyelia with Chiari malformation. One case showed additional hydrocephalus. Four cases were idiopathic, and 1 case was remotely posttraumatic. Magnetic resonance imaging, although it is in its infancy, already promises to be the most important radiographic technique for syringomyelia because it provides an anatomically truthful visualization of the sagittal plane of the cervical cord and can demonstrate the syrinx cavity and its relationship with the cerebellar tonsils, the 4th ventricle, and other related structures.     

Endoscopic third ventriculostomy for treatment of noncommunicating syringomyelia associated with a Chiari I malformation and hydrocephalus: case report and pathophysiological considerations

OBJECTIVE AND IMPORTANCE: A Chiari I malformation associated with syringomyelia and hydrocephalus is a rare condition. We report the successful use of endoscopic third ventriculostomy for the treatment of this pathological entity. The successful use of this technique in such a case has not been previously described, and the results allow us to speculate on the pathophysiological mechanism involved. CLINICAL PRESENTATION: A 34-year-old woman presented with headaches, a motor deficit of the right upper limb, and gait dyspraxia. Magnetic resonance imaging scans demonstrated dilation of all ventricles, compression of the retrocerebellar cerebrospinal fluid space, downward displacement of the tonsils, and syringomyelia. Syringomyelia involved the cervicodorsal cord below C3, with a syrinx-free segment between C1 and C3 and no enlargement of the rostral part of the central canal. INTERVENTION: Endoscopic third ventriculostomy resulted in prompt improvement of the clinical symptoms. Postoperative magnetic resonance imaging scans demonstrated shrinkage of the syrinx and return of the cerebellar tonsils to their physiological positions. CONCLUSION: This experience demonstrates that endoscopic third ventriculostomy, which is a simple, safe technique, may be the treatment of choice for associated Chiari I malformations, hydrocephalus, and syringomyelia (even the noncommunicating type).     

Emergency suboccipital decompression for respiratory arrest during supratentorial surgery: the untold story of a surgeon's courage in times of despair

The odyssey leading to the discovery of herniation syndromes was prolonged due to a lack of early understanding of the underlying pathophysiology. In 1896, Leonard Hill documented transtentorial pressure gradients as the intervening phenomenon involved in uncal herniation. In 1904, James Collier became the first to describe cerebellar tonsillar herniation as a "false localizing sign" often associated with intracranial tumors. During the infancy of neurological surgery, management of increased intracranial pressure and an improved understanding of brain herniation syndromes were of the utmost importance in achieving a safe technique. Harvey Cushing provided seminal contributions in understanding the pathophysiology of increased intracranial pressure and resulting cardiopulmonary effects. Cushing believed that tonsillar herniation was a cause of acute cardiorespiratory compromise in patients with intracranial tumors. In this vignette, we describe the untold story of Cushing's heroic attempt to treat respiratory arrest operatively during supratentorial tumor surgery with an emergency suboccipital craniectomy to relieve the medullary dysfunction that he believed was caused by compression from tonsillar herniation. This case illustrates a surgeon's determination and courage in fighting for his patient's life in the most desperate of times.     

Evaluation of cervical sagittal parameters on supine magnetic resonance imaging in patients with Chiari I malformation without syringomyelia

ObjectiveThe current study aimed to assess the effects of tonsillar herniation on cervical alignment in Chiari I patients without syringomyelia using new cervical sagittal alignment parameters, such as C0–2 Cobb angle, C2–7 cobb angle, T1 slope, and C2–7 sagittal vertical axis (SVA).MethodsTwo spinal surgeons independently evaluated midline T2-weighted sagittal magnetic resonance imaging findings of 28 Chiari I patients without syringomyelia and 40 patients without tonsillar herniation but with similar complaints. Thereafter, the measured C0–2 Cobb angle, C2–7 Cobb angle T1 slope, and C2–7 SVA were compared using the t-test.ResultsDifferences in the mean values for C2–7 Cobb angle, T1 slope, and C2–7 SVA were found between Chiari I patients and those without tonsillar herniation.ConclusionThe current study showed that Chiari I patients were less lordotic (kyphotic) compared to subjects without tonsillar herniation.