Direction-selective Resistance to Cerebrospinal Fluid Flow as the Cause of Syringomyelia.

The pathophysiology of syringomyelia remains poorly understood. Two prevailing challenges stand out: the need for a comprehensive understanding of its diverse types and the yet-to-be-explained mechanism of cerebrospinal fluid (CSF) retention in the syrinx despite its higher pressure than that in the adjacent subarachnoid space. Expanding on our previous proposal that direction-selective resistance to subarachnoid CSF flow drives syringomyelia genesis, this study uses a computer model to explore this mechanism further. We developed a computer simulation model to study spinal CSF dynamics, employing a lumped parameter approach with multiple compartments. This model replicated the to-and-fro movement of CSF in the spinal subarachnoid space and within an intraspinal channel. Subsequently, a direction-selective resistance-opposing only the caudal subarachnoid CSF flow-was introduced at a specific location within the subarachnoid space. Following the introduction of the direction-selective resistance, a consistent pressure increase was observed in the intraspinal channel downstream of the resistance. Importantly, this increase in pressure accumulated with every cycle of to-and-fro CSF flow. The accumulation results from the pressure drop across the resistance, and its effect on the spinal cord matrix creates a pumping action in the intraspinal channel. Our findings elucidate the mechanisms underlying our hypothesis that a direction-selective resistance to subarachnoid CSF flow causes syringomyelia. This comprehensively explains the various types of syringomyelia and resolves the puzzle of CSF retention in the syrinx despite a pressure gradient.

Modified Unilateral Approach for Ventrally Located Spinal Tumors.

Surgery on spinal tumors becomes challenging when the tumor is ventral to the spinal cord. Conventionally, we approach it posteriorly through bilateral laminectomy and rotate the cord after sectioning the dentate ligament and nerve roots. However, manipulating the cord can be hazardous, and a long bilateral laminectomy can be invasive. Meanwhile, a narrow operative field and a limited lateral viewing angle in a unilateral approach constrained the surgeon. To overcome these problems, we previously reported a technique of modified unilateral approach where we incised the skin and the fascia horizontally and placed a pair of retractors longitudinally.The current article reports our experience applying this approach in 15 patients with ventrally located spinal tumors. The approach was performed on 10 schwannomas, 2 meningiomas, and 3 others. We evaluated paraspinal muscle atrophy on postoperative magnetic resonance imaging.The modified unilateral approach provided an excellent surgical field for removing ventrally located tumors. Gross total removal was achieved in 11 patients (92% of benign tumors). No neurological complications occurred except for one case of transient weakness. We encountered no wound-related late complications such as pain or deformity. The reduction of the cross-sectional area of the paraspinal muscles on the approach side (compared to the nonapproach side) was 0.93 (95% confidence interval: 0.72-1.06), indicating 7% atrophy (statistically nonsignificant, p = 0.48).We believe this simple technique can be useful for removing spinal tumors located ventral to the spinal cord.

Long-term Outcomes after Microsurgical Decompression of Lumbar Foraminal Stenosis and Adverse Effects of Preoperative Scoliosis: A Prospective Cohort Study.

Lumbar foraminal stenosis is a common disorder, with surgical treatment varying from simple decompression to interbody fusion. It is often associated with degenerative lumbar scoliosis, but the effects of scoliosis on outcomes are unclear. The objectives of this study were to clarify long-term outcomes after microsurgical decompression of lumbar foraminal stenosis through Wiltse's approach and to determine the effects of scoliosis on these outcomes. A total of 86 consecutive patients with lumbar foraminal stenosis were prospectively followed after microsurgical decompression. They were categorized in multiple subcohorts with follow-up durations ranging from 6 months to 5 years. Outcomes were assessed using the Short Form 36 questionnaire (average physical scores and bodily pain scores). Local Cobb angle of the operative segment was measured preoperatively, and its effects on outcomes were analyzed. Average physical scores improved significantly from 33.8 (95% confidence interval [CI]: 29.1-38.5) preoperatively to 59.5 (95% CI: 54.6-64.3) at 6 months postoperatively and remained improved for 5 years. Bodily pain scores improved significantly from 23.7 (95% CI: 18.7-28.6) preoperatively to 56.3 (95% CI: 51.2-61.6) at 6 months postoperatively and remained improved for 5 years. Patients with preoperative scoliosis (local Cobb angle >10 degrees) had poorer outcomes: average physical scores were worse by 9.6 points (p = 0.07) and bodily pain scores were worse by 12.1 points (p = 0.02), compared with patients without scoliosis (local Cobb angle ≤10 degrees). Microsurgical foraminal decompression produced overall excellent outcomes in patients with lumbar foraminal stenosis. Preoperative scoliosis attenuated these beneficial effects.

Hypothesis on the pathophysiology of syringomyelia based on analysis of phase-contrast magnetic resonance imaging of Chiari-I malformation patients.

Background: Despite several hypotheses, our understanding of syringomyelia's pathophysiology remains limited. The hypothesis proposed by Oldfield et al. suggests that piston-like movement of the cerebellar tonsils propels the cerebrospinal fluid (CSF) into the syrinx via the spinal perivascular space. However, a significant question remains unanswered: how does the CSF enter and stay in the syrinx, which has a higher pressure than the subarachnoid space. In the current study, we attempted to verify Oldfield's hypothesis using phase-contrast magnetic resonance imaging (MRI) data from patients with syringomyelia. Methods: We analyzed phase-contrast MRI scans of 18 patients with Chiari-I malformation associated with syringomyelia, all of whom underwent foramen magnum decompression, and 21 healthy volunteers. We obtained velocity waveforms for CSF and brain tissue from regions of interest (ROI) set at the various locations. These waveforms were synchronized at the peak timing of downward CSF flow. We compared the preoperative patient data with the control data and also compared the preoperative patient data with the postoperative patient data. Results: The syrinx shrank in 17 (94%) of the patients, and they experienced significant clinical improvement. When comparing pre- and postoperative MRI results, the only significant difference noted was the preoperative elevated velocity of the cerebellar tonsil, which disappeared post-surgery. The CSF velocities in the subarachnoid space were higher in the preoperative patients than in the controls, but they did not significantly differ in the postoperative MRI. The tonsillar velocity in the preoperative MRI was significantly lower than that of the CSF, suggesting that the elevated tonsillar velocity was more of an effect, rather than the cause, of the elevated CSF velocity. Conclusions: Given these findings, a completely new paradigm seems necessary. We, therefore, propose a novel hypothesis: the generative force of syringomyelia may be the direction-selective resistance to CSF flow in the subarachnoid space.

Severe Spinal Cord Compression by Anomalous Vertebral Arteries Treated with Gore-Tex Tape Transposition Technique.

Rare anomalous courses of vertebral arteries in the craniovertebral junction may compress the spinal cord causing myelopathy. We report here the severest form of this pathologic condition successfully treated with transposition of bilateral vertebral artery using Gore-Tex tapes. A 73-year-old man presented with progressive tetraparesis and gait disturbance. Imaging studies showed bilateral atresia of the C1 transverse foramina and the both vertebral arteries penetrating the dura below the C1 lamina. Pinched by the vertebral artery loops on both sides, the spinal cord was severely deformed. Through the standard midline approach, we carefully transposed both vertebral arteries off the spinal cord, placing them at the optimal position using Tanaka et al's Gore-Tex tape technique originally reported for microvascular decompression. The Gore-Tex tape transposition technique proved to be versatile and useful for safe transposition of the vertebral artery in this challenging case.

Radical Intracapsular Dissection Technique for Dumbbell-Shaped Spinal Schwannoma with Intradural and Extradural Components.

BACKGROUND: Dumbbell-shaped spinal schwannomas with intradural and extradural components are associated with higher complication rates. This may be in part due to epineurial dissection of the extradural component, which inevitably damages the functioning nerve fibers beneath the epineurium and may lead to dural defects that are often difficult to repair. OBJECTIVE: The objective was to describe a radical intracapsular dissection technique that provides a simpler operative field with no need for dural repair and a better chance of preserving functioning nerve fibers. METHODS: The technique comprised the following: 1) exposure of the tumor while preserving spinal stability; 2) a single incision encompassing the dura and epineurium; 3) microsurgical dissection of the tumor just beneath the epineurium, preserving the viable nerve fibers; and 4) primary closure of the duroepineurial incision. We describe a case series of 7 patients in whom this type of tumor was excised using this technique. RESULTS: Gross total excision was achieved in 5 patients. In 1 patient with a large paravertebral component, the remaining tumor was removed with an additional anterior approach. No cerebrospinal fluid leak was noted, and no recurrence was observed in the median follow-up period of 36 months. CONCLUSIONS: The radical intracapsular dissection technique described herein represents an alternative technique for the removal of dumbbell-shaped spinal schwannomas with intradural and extradural components.

Probe Laminotomy: A Simple Technique for Precise Lateral Gutter Placement in Cervical Expansive Laminoplasty.

BACKGROUND: In cervical expansive laminoplasty, precise placement of lateral gutters is important. Placing them too medially results in suboptimal canal expansion, and placing them too laterally results in facet joint violation. However, precise placement is often difficult. METHODS: We have included a simple procedure called probe laminotomy in cervical expansive laminoplasty since 2013. This technique consisted of identifying the location of the pedicles through a small laminotomy with medial facetectomy before making lateral gutters. A case-control study was performed to compare the achieved postoperative canal area and duration of surgery between the original technique and the added probe laminotomy. RESULTS: The postoperative canal area was 21% larger in the probe laminotomy group compared with the standard technique group (P = 0.0003). There was no significant difference in duration of surgery between the groups. CONCLUSIONS: This technique facilitated more precise placement of the lateral gutter in cervical expansive laminoplasty, which resulted in a larger postoperative canal. This technique should be considered as an option in cervical expansive laminoplasty.

Effect of Sagittal Spinal Balance on the Outcome of Decompression Surgery for Lumbar Canal Stenosis.

OBJECTIVE: Although sagittal spinal balance is known to affect the outcome of spinal deformity surgery, its effect on simple decompression surgery is not well understood. MATERIALS AND METHODS: Patients who underwent unilateral laminotomy for bilateral decompression for lumbar canal stenosis were prospectively enrolled in the study. Before surgery and 6 months after surgery, the following sagittal-alignment parameters were measured: lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence minus lumbar lordosis (PI-LL), and sagittal vertical axis (SVA). At the same time, short-form 36 (SF-36) and Visual Analogue Scale (VAS) were estimated. The patients were divided into the poor postoperative physical score group (P_poor), good postoperative physical score group (P_good), poor postoperative VAS group (V_poor), or good postoperative VAS group (V_good). The postoperative spinopelvic parameters were compared between the physical score and VAS groups, respectively. Finally, we examined the correlation between the spinopelvic parameters and the outcome scores using scatter plots and linear regression analysis. RESULTS: Fifty-two patients were enrolled into the study. Although the spinopelvic parameters (LL, PT, PI-LL) significantly improved after surgery, the absolute values of improvement were relatively small. The postoperative spinopelvic parameters were significantly worse in the P_poor and the V_poor groups compared with the P_good and the V_good groups, respectively. The correlation analyses also showed that worse postoperative spinopelvic parameters correlated to worse outcome in SF-36 and VAS. CONCLUSIONS: Sagittal spinal balance significantly affected the outcome of patients undergoing decompression surgery for lumbar canal stenosis, the knowledge of which may serve better patient management.

Influence of Lumbar Lordosis on the Outcome of Decompression Surgery for Lumbar Canal Stenosis.

OBJECTIVE: Although sagittal spinal balance plays an important role in spinal deformity surgery, its role in decompression surgery for lumbar canal stenosis is not well understood. To investigate the hypothesis that sagittal spinal balance also plays a role in decompression surgery for lumbar canal stenosis, a prospective cohort study analyzing the correlation between preoperative lumbar lordosis and outcome was performed. METHODS: A cohort of 85 consecutive patients who underwent decompression for lumbar canal stenosis during the period 2007-2011 was analyzed. Standing lumbar x-rays and 36-item short form health survey questionnaires were obtained before and up to 2 years after surgery. Correlations between lumbar lordosis and 2 parameters of the 36-item short form health survey (average physical score and bodily pain score) were statistically analyzed using linear mixed effects models. RESULTS: There was a significant correlation between preoperative lumbar lordosis and the 2 outcome parameters at postoperative, 6-month, 1-year, and 2-year time points. A 10° increase of lumbar lordosis was associated with a 5-point improvement in average physical scores. This correlation was not present in preoperative scores. CONCLUSIONS: This study showed that preoperative lumbar lordosis significantly influences the outcome of decompression surgery on lumbar canal stenosis.

Posterior Paramedian Approach to Ventrally Located Spinal Meningioma.

BACKGROUND: To approach a ventral spinal pathology, a lateral viewing angle is often required. However, lateral approaches to the spine are usually more technically demanding and require a certain amount of surgical expertise. In this report, we describe a simple and easy technique to obtain the lateral viewing angle to the ventral spinal pathology. CASE DESCRIPTION: The technique is demonstrated in a ventrally located meningioma at the C2 level. Axial magnetic resonance imaging showed a square posterior shift of the spinal cord with little lateral space, which necessitated a more lateral viewing angle than the conventional posterior approach. With the patient in a prone position, we made a horizontal skin incision at the level of C2 and unilaterally exposed the right side of the C1 and C2 laminae. We then made a small perpendicular incision on the medial portion of the paravertebral muscles, which we retracted longitudinally. This approach provided an unobstructed lateral view toward the spinal cord. Following a gross total removal of the tumor with minimal cord retraction, the patient made an uneventful recovery. Her preoperative neurologic symptoms completely resolved in 2 months. No significant muscle atrophy was observed on postoperative magnetic resonance imaging at 3 months. There was no long-term complication related to the muscle incision at 1-year follow-up. CONCLUSION: The posterior paramedian approach is a simple and versatile technique to obtain lateral viewing angle to the spine and useful for approaching lesions residing ventral to the spinal cord.

Microsurgical Posterolateral Foraminotomy on Patients with Adult Isthmic Spondylolisthesis.

BACKGROUND: The standard surgical treatment for adult isthmic spondylolisthesis consists of various techniques of arthrodesis supplemented with instrumentation. However, the superiority of this strategy has not been irrefutably proved. Considering the risk associated with the instrumentation surgery, examining a less invasive approach is justified. METHODS: We describe a series of 9 patients with adult isthmic spondylolisthesis, in whom we microsurgically decompressed the responsible nerve root in the intervertebral foramen through the posterolateral intermuscular approach. Technical details specific to isthmic spondylolisthesis were reviewed. The 2-year outcome was assessed with Short Form 36 and visual analog scale scores. RESULTS: The mean age of the patients was 68 ± 7 years (standard deviation [SD]). The mean slip rate of spondylolisthesis measured on the preoperative lumbar radiography was 20% ± 12% (SD). All patients successfully underwent the procedure without complications. All the examined scores remained significantly better than the preoperative values 2 years after surgery; the mean visual analog scale score decreased from 7.8 ± 2.8 (SD) preoperatively to 2.8 ± 1.4 (SD) at 2 years (P = 0.008), average physical score of Short Form 36 improved from 33.1 ± 9.7 to 52.5 ± 9.4 (P = 0.001), and the bodily pain score improved from 28.0 ± 13.5 to 55.1 ± 9.7 (P = 0.001). CONCLUSIONS: Microsurgical decompression through the posterolateral intermuscular approach was effective in producing good 2-year outcome in patients with adult isthmic spondylolisthesis. This procedure may be considered as a less invasive alternative in the surgical treatment of adult isthmic spondylolisthesis.

A Theoretical Consideration of the Surgical Treatment of Small Unruptured Intracranial Aneurysms.

BACKGROUND: Surgical treatment of small, unruptured intracranial aneurysms remains a controversial topic. Recently, some authors have doubted the validity of the low rupture rates of small aneurysms reported in the literature and advocate aggressive surgical treatment of small unruptured aneurysms; however, some theoretical elucidation is necessary to determine whether such aggressive treatment is appropriate. METHODS: On certain theoretical assumptions, a simulation was performed to examine whether the low rupture rates for small aneurysms could produce a reasonable size distribution of ruptured aneurysms. Second, considering a hypothetical population in which all the unruptured aneurysms over a certain cut-off size are treated, the effect of this policy on reducing the incidence of subarachnoid hemorrhage (SAH) was mathematically analyzed. Then, the contribution of each individual operation to this reduction of SAH incidence was calculated. RESULTS: The low rupture rates reported in the literature produced a reasonable size distribution of ruptured aneurysms (median diameter of 10 mm) in the simulated population. The analysis of the treatment cut-off size showed that, as the cut-off size was progressively lowered to the range of 3-5 mm, further reduction of the incidence of SAH became almost negligible. The contribution of each individual surgery on unruptured aneurysms decreased rapidly as the aneurysm size decreased, and this reduction was proportional to the reduction of the rupture rate of the aneurysm. CONCLUSIONS: These results suggest that we should be prudent in providing surgical treatment to small unruptured intracranial aneurysms.

Increased flow signal in compressed segments of the spinal cord in patients with cervical spondylotic myelopathy.

STUDY DESIGN: Prospective controlled trial. OBJECTIVE: To describe a newly found increased flow signal in phase-contrast magnetic resonance imaging observed in compressed segments of the spinal cord in patients with cervical spondylotic myelopathy (CSM). SUMMARY OF BACKGROUND DATA: Derangement of cerebrospinal fluid movement in the spine is a well-known cause of syringomyelia. However, its possible role in CSM has not been studied well, despite the fact that similar derangement takes place in CSM. METHODS: In a consecutive series of 57 patients with CSM, cardiac-gated phase-contrast magnetic resonance imaging was analyzed. The amplitude of the flow signal obtained in the compressed segment of the spinal cord was compared with that obtained in the lesion-free C2 segment. It was also compared with controls obtained from 10 healthy volunteers. We also studied whether the amplitude was correlated with the severity of cervical canal stenosis, neurological symptoms, indication of surgery, and the presence of intramedullary high-intensity signal on T2-weighted images. In 33 patients who underwent decompression surgical procedures, we compared the amplitude of the flow signal between the preoperative and the postoperative study. RESULTS: Increased flow signal on phase-contrast study was seen in compressed segments of the spinal cord in 36 (63%) patients. The mean amplitude of the signal in the compressed segment was 0.64 ± 0.06 cm/s, whereas that in the C2 segment was 0.27 ± 0.01 and that in the controls was 0.28 ± 0.01. The flow signal linearly increased as the severity of canal stenosis increased. It significantly correlated with the symptom of upper-extremity dysesthesia, and the indication of surgery in these patients. The mean amplitude of the signal tended to be higher in those with intramedullary high-intensity signal than in those without. After decompression surgery, the increased flow signal was markedly diminished, and returned to a level comparable with the controls. CONCLUSION: Phase-contrast imaging demonstrated increased flow signal in compressed segments of the spinal cord in a majority of patients with CSM. This suggests a possible role played by derangement of cerebrospinal fluid movement in CSM. It also suggests potential usefulness of phase-contrast study in the management of patients with CSM. LEVEL OF EVIDENCE: 2.

Dorsal spinal arachnoid web diagnosed with the quantitative measurement of cerebrospinal fluid flow on magnetic resonance imaging.

An arachnoid web is an abnormal formation of the arachnoid membrane in the spinal subarachnoid space that blocks CSF flow and causes syringomyelia. Although the precise mechanism of syrinx formation is unknown, dissection of the arachnoid web shrinks the syrinx and improves symptoms. Precisely determining the location of the arachnoid web is difficult preoperatively, however, because the fine structure generally cannot be visualized in usual MRI sequences. In this report the authors describe 2 cases of arachnoid web in which the web was preoperatively identified using quantitative CSF flow analysis of MRI. By analyzing cardiac-gated phase-contrast cine-mode MRI in multiple axial planes, the authors precisely localized the obstruction of CSF flow on the dorsal side of the spinal cord in both patients. This technique also revealed a 1-way valve-like function of the arachnoid webs. Imaging led to the early diagnosis of myelopathy related to the derangement of CSF flow and allowed the authors to successfully excise the webs through limited surgical exposure.

Analysis of risk factors for chronic subdural haematoma recurrence after burr hole surgery: optimal management of patients on antiplatelet therapy.

OBJECTIVE. Not much is known about surgical management of patients with chronic subdural haematoma (CSDH) treated with antiplatelet or anticoagulant therapy. The aims of this study were to review the surgical outcomes of patients with CSDH and assess the risks of antiplatelet in their surgical management. METHODS. We retrospectively analysed 448 consecutive patients with CSDH treated by one burr hole surgery at our institution. Among them, 58 patients had been on antiplatelet therapy. We discontinued the antiplatelet agents before surgery for all 58 patients. For 51 of these 58 patients (87.9%), early surgery was performed within 0-2 days from admission. We analysed the association between recurrence and patient characteristics, including history of antiplatelet or anticoagulant therapy; age (< 70 years or ≥ 70 years); side; history of angiotensin receptor II blocker, angiotensin converting enzyme blocker, or statin therapy; and previous medical history of head trauma, infarction, hypertension, diabetes mellitus, haemodialysis, seizure, cancer, or liver cirrhosis. RESULTS. Recurrence occurred in 40 patients (8.9%), which was one of the lowest rates in the literature. Univariate analysis showed that only the presence of bilateral haematomas was associated with increased recurrence rate while antiplatelet or anticoagulant therapy did not significantly increase recurrence risk. Also, the recurrence rate from early surgery (0-2 days from drug cessation) for patients on antiplatelet therapy was not significantly higher than that from elective surgery (5 days or more after drug cessation). However, multivariate analysis revealed that previous history of cerebral infarction was an independent risk factor for CSDH recurrence. CONCLUSIOns. Our overall data support the safety of early surgery for patients on the preoperative antiplatelet therapy without drug cessation or platelet infusion. Patients with a previous history of infarction may need to be closely followed regardless of antiplatelet or anticoagulant therapy.

Degenerative spondylolisthesis does not affect the outcome of unilateral laminotomy with bilateral decompression in patients with lumbar stenosis.

STUDY DESIGN: Prospective subcohort study. OBJECTIVE: To determine whether preoperative presence of degenerative spondylolisthesis worsens the outcome of patients undergoing unilateral laminotomy with bilateral decompression for lumbar stenosis. SUMMARY OF BACKGROUND DATA: The standard surgical treatment for degenerative spondylolisthesis with lumbar stenosis is lumbar fusion after standard laminectomy. Although this strategy is widely adopted, it is not supported by class I evidence. This strategy assumes that degenerative spondylolisthesis worsens the outcome of laminectomy by causing postoperative instability. However, instability may be reduced or prevented by the use of less invasive decompression techniques. METHODS: To test the hypothesis that preoperative degenerative spondylolisthesis worsens the outcome of less invasive lumbar decompression, we performed a prospective cohort study of 165 consecutive patients who underwent unilateral laminotomy with bilateral decompression at our institution. The patients were prospectively followed with a standardized questionnaire, 36-Item Short Form Health Survey, and standing lumbar radiographs for a maximum follow-up period of 5 years. According to the presence or absence of degenerative spondylolisthesis, the patients were divided into 2 groups: an olisthesis group and a nonolisthesis group. RESULTS: The average 36-Item Short Form Health Survey physical score and bodily pain score improved substantially immediately after surgery. This improvement was maintained up to 5 years postoperatively. Progression of slippage was uncommon in both groups, with an overall incidence of 8% at 5 years of follow-up. There was no significant difference in the average physical score, the bodily pain score, or the rate of progression of slippage between the olisthesis and nonolisthesis groups. CONCLUSION: Our study thus indicates that preoperative degenerative spondylolisthesis does not worsen the outcome of patients with lumbar stenosis undergoing unilateral laminotomy with bilateral decompression. These results suggest that lumbar fusion is often unnecessary in patients with degenerative spondylolisthesis and lumbar stenosis if the posterior decompression technique is unilateral laminotomy with bilateral decompression. LEVEL OF EVIDENCE: 2.

Significance of radical resection for pilomyxoid astrocytoma of the cerebellum: a case report and review of the literature.

BACKGROUND: Pilomyxoid astrocytoma (PMA) was recently classified as a variant of pilocytic astrocytoma (PA) with significantly more aggressive clinical features than those of PA. Like PAs, PMAs frequently arise in the chiasmatic/hypothalamic regions. The cerebellum is also a common site of occurrence for PAs but not for PMAs. CASE DESCRIPTION: We present the case of a 31-month-old boy with cerebellar PMA that showed rapid regrowth during the 3 months following the first subtotal resection. Gross total resection was achieved in the second surgery, followed by radiation to the tumor bed. RESULTS: During follow-up over the next 12 years, there has been no evidence of recurrence on magnetic resonance imaging. CONCLUSIONS: Although the prognosis of cerebellar PMAs remains unknown because of the paucity of cases, the relevant literature reports a more favorable outcome for cerebellar PMAs than for PMAs occurring at other locations. The results of this case study and a review of the relevant literature advocate radical resection, sometimes involving multiple surgeries, for cerebellar PMAs because gross total or near total resection is more feasible in the cerebellum than in other locations.

Beneficial effect of selective intra-arterial infusion of fasudil hydrochloride as a treatment of symptomatic vasospasm following SAH.

INTRODUCTION: We envisage the efficacy and safety of intra-arterial infusion of fasudil hydrochloride (IAF) for symptomatic vasospasm (SVS) after subarachnoid hemorrhage (SAH). We compared results obtained from the groups that received selective IAF (a microcatheter inserted in intracranial arteries) and nonselective IAF (a microcatheter inserted in the cervical arteries). Glasgow Outcome Scale (GOS) value and computed tomographic (CT) score were used to evaluate clinical outcome and the extent of infarction due to delayed vasospasm. MATERIAL AND METHODS: Over 2 years, 113 patients with SAH underwent clipping or coiling. Among them, 31 patients (27.4%) developed SVS. We performed nonselective IAF in 10 patients and selective IAF in 10 other patients. Eleven patients with SVS were treated without IAF. The data were statistically analyzed. RESULT: By univariate linear regression analysis, IAF negatively correlated with CT score (p = 0.016), but IAF was significantly correlated with GOS (p = 0.035). By multiple regression analysis, Hunt and Kosnik grade and CT score significantly correlated with GOS. DISCUSSION: CT score significantly correlated with functional outcome. Although IAF, both selective and nonselective, was significantly effective for the treatment of delayed vasospasm, the former seemed to be more beneficial.

Syringomyelia associated with arachnoid septum at the craniovertebral junction, contradicting the currently prevailing theory of syringomyelia formation.

Despite a number of various hypotheses in the literature, the pathophysiology of syringomyelia is still not well understood. In this article, we report two cases of cervical syringomyelia not associated with Chiari I malformation. Both cases had a septum-like structure in the subarachnoid space on the dorsal side of the cord at the craniovertebral junction. Cardiac-gated phase-contrast cine-mode magnetic resonance imaging (MRI) demonstrated decreased cerebrospinal fluid (CSF) flow on the dorsal side of the spinal cord. Surgical excision of this septum, restoring the CSF flow, resulted in a prompt reduction of the syrinx size in both cases. Findings in these cases contradict the currently prevailing hypothesis of syrinx formation that postulate that the piston-like movement of the cerebellar tonsils enhance the pulsatile CSF flow in the spinal subarachnoid space, driving the CSF into the syrinx through the perivascular space of Virchow and Robin. The authors propose that a mechanism based on the decreased pulsatile CSF flow in the spinal subarachnoid space will be more suitable as a hypothesis in studying the pathophyisiology of syringomyelia. These cases also provide an important lesson in managing the patients with syringomyelia not associated with Chiari I malformation.