Concept: Cauda equina
The spinal canal is frequently a source of difficulties, traps and diagnostic errors. Pitfalls related to artifacts are resolved by using appropriate sequences. Good knowledge of the appearance of certain particular anatomical structures (the cauda equina roots, the radicular veins of the lumbar spine and conus medullaris, the dorsal root ganglion) and of frequent variants (fibrolipoma of the filum terminale, common root sheaths, root cysts) will avoid a good many errors. Dilatation of epidural veins in intracranial hypotension can simulate the contrast enhancement of a tumour. An increase in epidural fat can induce pathogenic stenosis of the dural sheath.
Object The pathophysiology of occult tethered cord syndrome (OTCS) with no anatomical evidence of a caudally shifted conus and a normal terminal filum is hard to understand. Therefore, the diagnosis of OTCS is often difficult. The authors hypothesized that the posterior displacement of the terminal filum may become prominent in patients with OCTS who are in a prone position if filum inelasticity exists, and they investigated prone-position MRI findings. Methods Fourteen patients with OTCS and 12 control individuals were examined using T2-weighted axial MRI with the patients in a prone position on a flat table. On each axial view, the distance between the posterior and anterior ends of the subarachnoid space (A), the distance between the posterior end of the subarachnoid space and the terminal filum (B), the distance between the posterior end of the subarachnoid space and the dorsal-most nerve among the cauda equina ©, and the distance between the posterior end of the subarachnoid space and the ventral-most nerve (D) were measured. The location ratios of the terminal filum, the dorsal-most nerve, and the ventral-most nerve were calculated by the ratio of A to B (defined as TF = B/A), A to C (defined as DN = C/A), and A to D (defined as VN = D/A), respectively. Patients underwent sectioning of the terminal filum with the aid of a surgical microscope. The low-back pain Japanese Orthopaedic Association score was obtained before surgery and at the final follow-up visit. Results On prone-position axial MRI, the terminal filum was separated from the cauda equina and was shifted caudally to posterior in the subarachnoid space in all patients with OTCS. The locations of the caudal cauda equina shifted to ventral in the subarachnoid space. The TF values in the OTCS group were significantly lower than those in the control group at the L3-4 (p = 0.023), L-4 (p = 0.030), L4-5 (p = 0.002), and L-5 (p < 0.001) levels. In contrast, the DN values in the OTCS group were significantly higher than those of the control group at the L-2 (p = 0.003), L2-3 (p = 0.002), L-3 (p < 0.001), L3-4 (p < 0.001), L-4 (p = 0.007), L4-5 (p = 0.003), and S-1 (p = 0.014) levels, and the VN values in the OTCS group were also significantly higher than those of the control group at the L2-3 (p = 0.022), L-3 (p = 0.027), L3-4 (p = 0.002), L-4 (p = 0.011), L4-5 (p = 0.019), and L5-S1 (p = 0.040) levels. Sections were collected during surgery for histological evaluation, and a decreased elasticity within the terminal filum was suggested. Improvements in the Japanese Orthopaedic Association score were observed at the final follow-up in all patients. Conclusions The authors' new method of using the prone position for MRI shows that the terminal filum is located significantly posterior and the cauda equina is located anterior in patients with OTCS, suggesting a difference in elasticity between the terminal filum and cauda equina.
Cauda equina syndrome (CES) is a rare but important neurosurgical emergency. Despite being a recognised clinical entity since 1934, there remains significant uncertainty in the literature regarding the urgency for its surgical intervention. The past decade has seen the emergence of the much referred to 48-hour limit as a possible window of safety. The ramifications of this time-point are significant for early patients who may subsequently have urgent treatment delayed, and for litigation cases after which adverse decisions are more likely to occur.
Study Design. Retrospective descriptive study of an innovative surgical technique for thoracolumbar fracture patients.Objective. To describe the transthecal approach for thoracolumbar fracture patients and demonstrate its safety and effectiveness.Summary of Background Data. The goals of surgery in patients with thoracolumbar fracture include neural decompression, reestablishing stability, reduction of deformity, and repair of dural laceration and the damaged neural elements. The traditional posterior approach may only accomplish the former three goals.Methods. Simply opening the dura during the traditional posterior approach enables accomplishment of all the aforementioned goals, which would not be possible through an anterior or posterior approach alone.Results. We have successfully performed the transthecal approach in 5 patients with thoracolumbar burst fracture with cauda equina fiber injury. Neural decompression, reestablishing stability, reduction of deformity, and repair of dural laceration and the damaged cauda equina fiber were all achieved in these patients. No complications were noted.Conclusion. The transthecal approach can be applied to patients with thoracolumbar burst fracture to achieve neural decompression, reestablishing stability, reduction of deformity, and repair of dural laceration and the damaged cauda equina fiber. This approach may be an alternative to combined (circumferential) surgery.
Myxopapillary ependymoma (MPE) is a rare variant of ependymoma which usually occurs in the conus medullaris or the filum terminale. It is usually a single encapsulated lesion.
A large number of patients do not have cauda equina syndrome (CES) on MRI to account for their clinical findings; consequently, the majority of urgent scans requested are normal. We aimed to determine whether any clinical manifestation of CES, as stated in Royal College of Radiology guidelines, could predict the presence of established CES on MRI. We also aimed to support a larger study to develop a more universal assessment tool for acute lower back pain.A retrospective analysis of consecutive patients who warranted urgent MRI was conducted. Seventy-nine patients were eligible for study. The Kendall’s tau test was used for statistical analysis of all data. A p value of less than 0.05 was considered to be significant. MRI was performed in 62 patients out of 79.A total of 32.9% of patients had scans within 24 hours of admission. Nine of these patients were referred to neurosurgery for urgent neurosurgical review. Of these, 6.3% of patients had an established CES on MRI scan. One patient who had an out-patient MRI spine (15 days from hospital presentation) was found to have an established CES, was urgently referred to spinal surgery and underwent primary fenestration excision of the lumbar vertebra. No clinical features that were able to predict the presence of an established CES on MRI were elucidated. Findings included decreased anal tone 7.6% (p = 0.282), faecal incontinence 3.8% (p = 0.648), urinary retention 7.6% (p = 0.510), bladder incontinence 8.9% (p = 0.474), constipation 2.5% (p = 0.011) and saddle anaesthesia 8.9% (p = 0.368). Patients who had an abnormal MRI spine for back pain prior to this presentation showed a correlation with a newly diagnosed CES on MRI (p = 0.016) with a correlation coefficient of 0.272.
Fifty-six human and animal studies of cauda equina syndrome (CES) were reviewed. The evidence from human studies was poor (level IV). Evidence from animal studies and limited evidence from human studies suggest that structural and functional neurological losses are a progressive, continuous process. The longer the cauda equina nerve roots are compressed the greater the harm and the poorer the extent of recovery. This should prompt diagnosis and surgery for all CES patients as soon as practicably possible.
The authors present a case of anterior sacral meningocoele demonstrating a clinical picture of cauda equina syndrome. To the best of our knowledge, such presentation has not yet been reported.
Study Design Case report. Objective Present a case of Foix-Alajouanine syndrome that presented as acute cauda equina syndrome and discuss the pathophysiology and management. Methods An adult male patient developed sudden onset of back pain and leg pain with weakness of the lower limbs and bladder/bowel dysfunction typical of cauda equina syndrome. Emergency magnetic resonance imaging revealed no compressive lesion in the spine but showed tortuous flow voids and end-on blood vessels in the peridural region suggesting spinal arteriovenous malformation resulting in Foix-Alajouanine syndrome. Results The case was managed by endovascular embolization with excellent results. The pathophysiology, imaging features, management, and literature review of the syndrome is discussed. Conclusion The authors conclude that this condition may be an important differential diagnosis for cauda equina syndrome.
Cauda equina syndrome typically requires emergent MR imaging to detect compressive lesions on the cauda equina, which may require surgical decompression. While CT is sometimes performed as a complementary imaging technique to evaluate osseous integrity in patients with cauda equina syndrome, the accuracy of CT in detecting significant spinal stenosis and cauda equina impingement is not well-defined in the literature. We hypothesized that percentage thecal sac effacement on CT of the lumbar spine would have high sensitivity and high negative predictive value in evaluating significant spinal stenosis and cauda equina impingement.