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.     

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.     

Unraveling the riddle of syringomyelia

The pathophysiology of syringomyelia development is not fully understood. Current prevailing theories suggest that increased pulse pressure in the subarachnoid space forces cerebrospinal fluid (CSF) through the spinal cord into the syrinx. It is generally accepted that the syrinx consists of CSF. The here-proposed intramedullary pulse pressure theory instead suggests that syringomyelia is caused by increased pulse pressure in the spinal cord and that the syrinx consists of extracellular fluid. A new principle is introduced implying that the distending force in the production of syringomyelia is a relative increase in pulse pressure in the spinal cord compared to that in the nearby subarachnoid space. The formation of a syrinx then occurs by the accumulation of extracellular fluid in the distended cord. A previously unrecognized mechanism for syrinx formation, the Bernoulli theorem, is also described. The Bernoulli theorem or the Venturi effect states that the regional increase in fluid velocity in a narrowed flow channel decreases fluid pressure. In Chiari I malformations, the systolic CSF pulse pressure and downward motion of the cerebellar tonsils are significantly increased. This leads to increased spinal CSF velocities and, as a consequence of the Bernoulli theorem, decreased fluid pressure in narrow regions of the spinal CSF pathways. The resulting relatively low CSF pressure in the narrowed CSF pathway causes a suction effect on the spinal cord that distends the cord during each systole. Syringomyelia develops by the accumulation of extracellular fluid in the distended cord. In posttraumatic syringomyelia, the downwards directed systolic CSF pulse pressure is transmitted and reflected into the spinal cord below and above the traumatic subarachnoid blockage, respectively. The ensuing increase in intramedullary pulse pressure distends the spinal cord and causes syringomyelia on both sides of the blockage. The here-proposed concept has the potential to unravel the riddle of syringomyelia and affords explanations to previously unanswered clinical and theoretical problems with syringomyelia. It also explains why syringomyelia associated with Chiari I malformations may develop in any part of the spinal cord including the medullary conus. Syringomyelia thus preferentially develops where the systolic CSF flow causes a suction effect on the spinal cord, i.e., at or immediately caudal to physiological or pathological encroachments of the spinal subarachnoid space.     

Pathogenesis of syringomyelia associated with Chiari type 1 malformation: review of evidences and proposal of a new hypothesis

The exact pathogenesis of syringomyelia associated with Chiari type 1 malformation is unknown, although a number of authors have reported their theories of syrinx formation. The purpose of this review is to understand evidences based on the known theories and to create a new hypothesis of the pathogenesis. We critically review the literatures on clinicopathological, radiological, and clinical features of this disorder. The previously proposed theories mainly focused on the driven mechanisms of the cerebrospinal fluid (CSF) into the spinal cord. They did not fully explain radiological features or effects of surgical treatment such as shunting procedures. Common findings of the syrinx in clinicopathological studies were the communication with the central canal and extracanalicular extension to the posterior gray matter. Most of the magnetic resonance imaging studies demonstrated blockade and alternated CSF dynamics at the foramen magnum, but failed to show direct communication of the syrinx with the CSF spaces. Pressure studies revealed almost identical intrasyrinx pressure to the subarachnoid space and decreased compliance of the spinal CSF space. Recent imaging studies suggest that the extracellular fluid accumulation may play an important role. The review of evidences promotes a new hypothesis of syrinx formation. Decreased absorption mechanisms of the extracellular fluid may underlie the pathogenesis of syringomyelia. Reduced compliance of the posterior spinal veins associated with the decreased compliance of the spinal subarachnoid space will result in disturbed absorption of the extracellular fluid through the intramedullary venous channels and formation of syringomyelia.     

Spinal cord edema preceding syringomyelia associated with Chiari I malformation--case report

A 38-year-old woman with Chiari I malformation presented with spinal cord edema preceding syringomyelia manifesting as a 5-month history of nuchal pain and numbness of the upper extremities. Magnetic resonance imaging showed spinal cord edema, a poorly defined syrinx at the C-2 to T-2 levels, and distorted cerebellar tonsils. Computed tomography revealed cerebrospinal fluid (CSF) density in the center of spinal cord edema, and positron emission tomography revealed no uptake of L-[methyl-11C]methionine, indicating a non-neoplastic lesion. Craniocervical decompression achieved excellent clinical and neuroradiological outcomes. The success of surgical treatment supports the theory that patients with Chiari I malformation have increased transmural flow of CSF, causing spinal cord edema that progresses to syringomyelia. Early treatment of patients with spinal cord edema is indicated to prevent permanent spinal cord injury due to progressive syringomyelia.     

Quantitative analysis of cervical CSF and syrinx fluid pulsations

The author has performed quantitative studies of cerebrospinal fluid (CSF) pulsations in the cervical region in 10 normal subjects and in 13 cases of syringomyelia using a superconducting MRI system. In the normal subjects, the caudally directed CSF flow in the anterior subarachnoid space reached its maximum velocity at 100-200 msec after the R-wave of the ECG. Measured velocities were 26-44 mm/sec at upper cervical levels and 44-124 mm/sec at lower cervical levels. Further small peaks in the caudal direction were seen at approximately 500 msec after the R-wave. Cases of syringomyelia showed lower velocities in the syrinx than in the anterior subarachnoid space, and the movements varied greatly between the cases and levels examined. CSF pulsations in the subarachnoid space were observed in all cases with Chiari malformation. These results suggest that CSF pulsations in the subarachnoid space are transmitted to the syrinx fluid, and that the movements of the syrinx fluid are influenced by various factors.     

Subarachnoid pressure-dependent change in syrinx size in a patient with syringomyelia associated with adhesive arachnoiditis. Case report

The pathophysiology of syringomyelia is still not well understood. Current prevailing theories involve the assumption that cerebrospinal fluid (CSF) flows into the syrinx from the subarachnoid space through the perivascular space of Virchow-Robin. Reported here is the case of a patient with syringomyelia in which this course is clearly contradicted. This patient with a holocord syrinx associated with adhesive arachnoiditis was treated 3 years previously with insertion of a subarachnoid-peritoneal shunt and had recently experienced worsening myelopathy. On surgical exploration, the shunt system was functioning normally. The medium-pressure shunt valve was replaced with an adjustable valve with a higher closing pressure setting, thus increasing the CSF pressure in the subarachnoid space. Contrary to prevailing theories, this procedure markedly reduced the size of the syrinx. This case provides direct evidence that the syrinx size is inversely related to subarachnoid CSF pressure and supports the hypothesis that the pressure gradient across the spinal cord parenchyma is the force that generates syringes in syringomyelia.     

Syringomyelia, its pathogenesis and surgical treatment based on 4 cases' experience

Four cases of syringomyelia, each were considered to have different pathogenesis of syrinx and presented different clinical and radiological pictures, are reported. Case I was associated with Chiari I malformation and the syrinx communicated with the fourth ventricle through the central canal, case 2 was associated with Chiari II malformation and the syrinx was not communicated with the fourth ventricle, case 3 was thought to be traumatic and case 4 to be arachnoiditis due to unknown etiology. Metrizamide CT myelography was most valuable diagnostic technique to disclose the syringomyelic cavity and its extension. The cases except case 1 showed central opacification without via fourth ventricle, suggesting transneural migration CSF as shown by Aubin et al. Surgical treatment, therefore, was different in each case to obtain normal CSF dynamics. Case 1 was treated by suboccipital craniectomy, muscle plugging to the obex and syringo-subarachnoid shunt. In case 2 syringo-cisternal shunt was done in addition to suboccipital craniectomy. In case 3 syringocisternal shunt was done after laminectomy. In case 4 syringo-peritoneal shunt was performed. All but case 4 were obtained favorable result and case 4 was unfavorable except the disappearance of girdle sensation. For traumatic or inflammatory syringomyelia with tight adhesion between pia and arachnoid membrane in subarachnoid space, syringocisternal shunt was good way to obtain normal CSF dynamics and was expected to relieve the neurological deterioration.     

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.     

A successful treatment for a case of idiopathic syringomyelia with syrinx located in the anterior horn

Idiopathic syringomyelia not associated with Chiari malformation, tumor, nor tetherd cord syndrome has not been frequently reported. So the clinical significance and optimum treatment strategy for this disease remains unclear. We report a 37-year-old man who was diagnosed as having idiopathic syringomyelia and was treated successfully using implantation of a syringo-subarachnoid shunt. The patient suffered gradual worsening of sensory disturbance in the upper extremities, and Magnetic resonance imaging demonstrated a large syrinx located in the cervical spinal cord (C2-3), located mainly at the left anterior horn. We performed syringo-subarachnoid shunt for syringomyelia under partial hemilaminectomy. During the surgery, the spinal cord was markedly rotated and dorsal root entry had shifted to the midline because of the large syrinx. In order to perform myelotomy at the dorsal root entry zone, we needed additional drilling to the medial portion of the lamina. After this procedure, we were able to perform implantation of the syringo-subarachnoid shunt safely. After the operation, the syrinx collapsed immediately and no neurological deficit was observed. The patient was discharged 2 weeks after the operation. Idiopathic syringomyelia in which the syrinx has deviated to the anterior horn is rare. In those cases, we consider that sufficient hemilaminectomy for the midline should be performed.     

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.     

Clinical features and pathomechanisms of syringomyelia associated with spinal arachnoiditis

BACKGROUND: Syringomyelia is a common intramedullary lesion associated with spinal arachnoiditis and obstruction of the foramen magnum such as in Chiari's malformation. Disturbance of cerebrospinal fluid flow around the spinal cord has an important role in the development of syringomyelia due to spinal arachnoiditis; however, the exact mechanisms have not been clarified. The purpose of this retrospective study is to understand the clinical features and pathomechanisms of syringomyelia secondary to spinal arachnoiditis and to provide the current choice of surgical treatment in this difficult clinical entity. METHODS: Clinical and radiological findings in 15 patients with syringomyelia associated with spinal arachnoiditis who underwent surgical treatment in our institutes between 1982 and 2000 were reviewed. All patients presented with paraparesis or tetraparesis on admission. RESULTS: Magnetic resonance imaging (MRI) or computed tomography-myelography revealed that the syrinx predominantly existed at the thoracic levels. Five patients showed complete block of the thoracic subarachnoid space by conventional myelography. T2-weighted MRI showed diffuse intramedullary hyperintensity at the level of arachnoiditis. As the first surgical treatment, 10 patients underwent syringo-peritoneal shunt placement. Three patients were treated with a syringo-subarachnoid shunt, and 2 patients were treated with a ventriculoperitoneal shunt. Eight patients required further shunting operations for syringomyelia 2 months to 12 years after the first surgery. Neurologic improvement was obtained in 9 patients (60%) with decreased size of the syrinx. One patient remained stable; 5 patients showed gradual deterioration. CONCLUSIONS: The syrinx originated from the thoracic levels where severe adhesion of the subarachnoid space was present. The mechanisms of syrinx formation may be based on the increased interstitial fluid in the spinal cord. Shunting procedures were effective in some population of the patients. Decompression procedures of the spinal subarachnoid space may be an alternative primary surgical treatment except for patients with longitudinally extensive arachnoiditis.     

Endoscopic fenestration of posterior fossa arachnoid cyst for the treatment of presyrinx myelopathy--case report

A 32-year-old man presented with an arachnoid cyst of the posterior fossa manifesting as cervical syringomyelic myelopathy. Magnetic resonance (MR) imaging demonstrated edematous enlargement and T2 prolongation of the cervical spinal cord, indicating a "presyrinx" state. MR imaging showed the inferior wall of the cyst, which disturbed cerebrospinal fluid (CSF) pulsatile movement between the intraspinal and intracranial subarachnoid spaces. The cyst wall was fenestrated with a neuroendoscope. The presyrinx state and the CSF movement improved. Posterior fossa arachnoid cyst, as well as Chiari malformation, can cause CSF flow disturbance at the craniocervical junction and syringomyelia. Endoscopic fenestration is less invasive than foramen magnum decompression and should be the procedure of choice.     

Expansive Suboccipital Cranioplasty for the Treatment of Syringomyelia Associated with Chiari Malformation

Summary  In order to treat syringomyelia associated with adult type Chiari malformation, the authors developed a method of expansive suboccipital cranioplasty (ESC) that involves enlarging the small posterior fossa to obtain a sufficient flow of cerebrospinal fluid (CSF). The relative effectiveness of ESC with the obex plugged and not plugged was also examined, as well as other factors influencing the operative results.  Twenty patients without arachnoid adhesion at the major cistern underwent ESC without opening the arachnoid membrane at the major cistern. After surgery, all improved with no recurrence and CSF flow study using magnetic resonance (MR) imaging showed significant improvement of the flow at the major cistern. Another 20 patients without arachnoid adhesion also underwent ESC but with obex plugging. Sixteen improved and one displayed only temporary improvement with recurrent syringomyelia due to postoperative arachnoid adhesions. The remaining three showed no change in spite of shrinkage of the syrinx on postoperative MR imaging. These three patients had displayed pre-operative symptoms over an approximately 10-year period involving almost the entire axial plain of the spinal cord, and presented a large syrinx before surgery. In 4 patients with arachnoid adhesions, all required intra-arachnoid procedures in addition to ESC.  Intra-arachnoid procedures are not necessary to facilitate restoration of CSF flow in patients without arachnoid adhesions, because ESC can release the CSF flow blockage in the major cistern even without plugging of the obex. An associated arachnoid adhesion at the major cistern or a long-standing syringomyelia with irreversible damage of the spinal cord results in a poor operative prognosis. When posterior fossa surgery fails, insufficient decompression or postoperative arachnoid adhesions at the major cistern as the cause of treatment's failure should be evaluated by CSF flow studies using phase contrast MR imaging.     

Terminal syringomyelia: is it as innocent as it seems?--Case report

A 5-day-old newborn girl presented with cutaneous signs of hypertrichosis, skin dimple, and subcutaneous lipoma in the lumbar region. Magnetic resonance (MR) imaging of the thoracolumbar spine demonstrated spinal dermal sinus, type II split cord malformation, and tethered cord. A small terminal syringeal cavity was also present. Five months after the diagnosis, weakness in dorsal flexion of the bilateral feet and toes was detected. Surgery to untether the cord was performed. Her deficits resolved completely. Nearly 4 years later, she was admitted with weakness in dorsal flexion of the right foot and toe. MR imaging of the spine showed holocord syringomyelia, postoperative changes, and tethered cord. No Chiari malformation was seen. Syringosubarachnoid shunt placement was performed. Terminal syringomyelia is common in cases of occult spinal dysraphism, but the natural history and management remain unclear. Progression, regression, or persistence of terminal syringeal cavity can occur whether untethering is performed or not. Progression of the terminal syrinx occurred after tethered cord release and the enlargement of the cavity involved the entire spinal cord in the present case. Terminal syringomyelia requires close follow up for a long time even in asymptomatic cases. Surgical treatment should be considered in symptomatic cases.     

Pathophysiology of headache associated with cough in patients with Chiari I malformation

OBJECT: The aim of this study was to evaluate the pathophysiology underlying headache associated with cough in patients with Chiari I tonsillar abnormality. The authors hypothesized that peak intrathecal pressure during coughing is higher in patients with headache aggravated by cough than in patients without or in healthy volunteers. In addition, the authors evaluated the use of intrathecal pressure during cough as a means of assessing obstruction to the free flow of cerebrospinal fluid (CSF) at the craniocervical junction. METHODS: Twenty-six adult patients with Chiari I malformation and syringomyelia, four adult patients with Chiari I malformation without syringomyelia, and 15 healthy volunteers were prospectively studied. Testing before surgery included the following: 1) clinical evaluation for the presence of headache associated with cough; and 2) evaluation of lumbar subarachnoid pressure at rest, during three to five coughs, while performing the Valsalva maneuver, during jugular compression, and after removal of CSF. Patients underwent suboccipital craniectomy, C-1 laminectomy, and duraplasty. Testing was repeated 6 months after surgery. CONCLUSIONS: Peak intrathecal pressures during cough and at baseline were elevated in patients with headache associated with cough compared with either patients without headache or healthy volunteers. After surgery, intrathecal pressures during cough were significantly lower than preoperative values and headache aggravated by cough was resolved partially or completely. Headache linked to coughing in patients with Chiari I malformation is associated with sudden increased intrathecal pressure caused by obstruction to the free flow of CSF in the subarachnoid space.     

Spontaneous resolution of a Chiari I malformation associated syringomyelia in one child

Summary A child with complete spontaneous resolution of a Chiari I malformation associated Syringomyelia without surgical intervention is presented. The child was followed clinically by serial magnetic resonance imaging (MRI) and remains neurologically stable after 8-years of follow-up. To our knowledge, only 6 pediatric cases with spontaneous resolution of a spinal cord syrinx documented by MRI without surgical intervention have been reported. This case is of interest in the light of the postulated theories to explain spontaneous resolution of syringomyelia.     

Nontraumatic cervicothoracic syrinx as a cause of progressive neurologic dysfunction

BACKGROUND/OBJECTIVE: Syringomyelia is characterized by a fluid-filled cavity within the spinal cord. While its pathogenesis is currently debated, the relationship of syringomyelia with other conditions, such as Chiari I malformation and cord/column trauma, is well accepted. Despite these common associations, a nidus for syrinx formation has not been identified in a subset of patients. We report 2 patients with idiopathic cervicothoracic syringomyelia who presented with progressive neurologic dysfunction. Diagnostic and treatment algorithms used in the care of these patients are presented. METHODS: Retrospective review, including preoperative and postoperative studies, intraoperative findings, and the patients' surgical outcomes. RESULTS: Patients underwent laminectomy, lysis of adhesions, untethering of spinal cord, fenestration of syrinx, and duraplasty after preoperative studies demonstrated evidence of focal cerebrospinal fluid flow block at the level of the syrinx. One patient's neurologic condition improved after surgery, whereas the other's remained unchanged without further deterioration; both showed radiographic decrease in the syrinx on immediate postoperative magnetic resonance imaging. CONCLUSIONS: These 2 cases illustrate patients who develop a cervicothoracic syrinx in the absence of any trauma, infection, previous manipulation of the neuraxis, or malformations known to be associated with a syringomyelia. Whereas there is no consensus on the optimal management of these patients, the patients reported here experienced arrest in deterioration or improvement of their neurologic examination, making the identification of this condition important as a potentially reversible cause of neurologic deficits. Long-term follow-up is required to determine the efficacy, durability, and lifestyle impact of the procedure.     

Three-dimensional constructive interference in steady-state magnetic resonance imaging in syringomyelia: advantages over conventional imaging

OBJECT: Neuroradiology has become indispensable in detecting the pathophysiology in syringomyelia. Constructive interference in steady-state (CISS) magnetic resonance (MR) imaging can provide superior contrast at the sub-arachnoid tissue borders. As this region is critical in preoperative evaluation, the authors hypothesized that CISS imaging would provide superior assessment of syrinx pathology and surgical planning. METHODS: Based on records collected from a database of 130 patients with syringomyelia treated at the authors' institution, 59 patients were prospectively evaluated with complete neuroradiological examinations. In addition to routine acquisitions with FLAIR, T1- and T2-weighted, and contrast-enhanced MR imaging series, the authors obtained sagittal cardiac-gated sequences to visualize cerebrospinal fluid (CSF) pulsations and axial 3D CISS MR sequences to detect focal arachnoid webs. Statistical qualitative and quantitative evaluations of spinal cord/CSF contrast, spinal cord/CSF delineation, motion artifacts, and artifacts induced by pulsatile CSF flow were performed. RESULTS: The 3D CISS MR sequences demonstrated a contrast-to-noise ratio significantly better than any other routine imaging sequence (p < 0.001). Moreover, 3D CISS imaging can detect more subarachnoid webs and cavitations in the syrinx than T2-weighted MR imaging with less flow-void artifact. The limitation of 3D CISS imaging is a susceptibility to motion artifacts that can cause reduced spatial resolution. Lengthy acquisition times for axial segments can be reduced with multiplanar reconstruction of 3D CISS-generated sagittal images. CONCLUSIONS: Constructive interference in steady-state imaging is the MR sequence of choice in the preoperative evaluation of syringomyelia, allowing significantly higher detection rates of focal subarachnoid webs, whereas standard T2-weighted MR imaging shows turbulent CSF flow voids. Constructive interference in steady-state MR imaging enables the neurosurgeon to accurately identify cases requiring decompression for obstructed CSF. Motion artifacts can be eliminated with technical variations.     

Non-hindbrain-related syringomyelia. Obstruction of the subarachnoid space and the central canal in rats. An experimental study

BACKGROUND: The aim is to determine the mechanism of non-hindbrain-related syringomyelia in experimental models. The effects of obstruction of central canal and subarachnoid space on occurrence of cavities were discussed. METHODS: 31 Sprague-Dawley rats were used with eight (Group D) as a control. In 10 rats (Group A) 1.5 microl kaolin was microinjected into the dorsal columns and central gray matter of the spinal cord at the level of Th6-10. In 10 rats (Group B) 0.1 cc kaolin was injected into the subarachnoid space at the same level. In 3 rats (Group C), 1.5 microl kaolin was administered into both dorsal midline of the spinal cord and the subarachnoid space. RESULTS: In Group A, histological examination revealed cystic cavity and dilatation of the central canal in five rats; denuded ependymal line and multicystic formations in ependymal and periependymal areas in seven rats. In Group B, denuded ependymal line in three rats and microcystic formations in ependymal and periependymal areas in four rats were revealed. In Group C, there were microcystic formations in two rats and syrinx cavity in one rat. CONCLUSIONS: Developments leading to occurrence of cavities are focused on the central canal in all groups. These models indicate that the CSF-flow is from the subarachnoid space to the central canal leading to changes of cavities. In cases of obstruction of the subarachnoid space or the central canal, the occurrence of syrinx cavity initially is due to increased CSF (cerebrospinal fluid) pressure in the central canal. Flow changes in spinal cord is indicated by this study.