Lipomas of the cauda equina and other fatty tumours related to neurospinal dysraphism

Comparison of the inter-laminar approach and laminotomy open approach for filum terminale lipoma: A retrospective analysis

PURPOSE

Filum terminale lipoma (FTL) causes spinal-cord tethering and is associated with tethered-cord syndrome, which is treated by dissection of the entrapment. The conventional treatment for FTL involves dissection of the spinal cord through a laminotomy open approach (LOA). However, in recent years, the interlaminar approach (ILA) has gained popularity as a minimally invasive surgery. This study compares the effectiveness of the minimally invasive ILA with the conventional LOA in treating FTL.

METHODS

We retrospectively evaluated data on the ILA and LOA for FTL at our center. In total, 103 participants were enrolled, including 55 in the ILA group and 48 in the LOA group.

RESULTS

The ILA required significantly less surgical time and resulted in less blood loss. The improvement rate of symptoms in symptomatic patients was 84%, and for urinary symptoms and abnormal urodynamic study findings, it was 77%. The postoperative maintenance rate for asymptomatic patients was 100%. Postoperative complications of ILA included delayed wound healing in two patients (3.6%).

CONCLUSION

Compared with LOA, ILA offers advantages in terms of shorter operative time and less blood loss, with no significant difference in long-term symptom-improvement rates between the groups.

Beyond the abdominal and pelvic cavity: abdominal wall and spinal "Aunt Minnies"

Abdominal wall and spinal soft tissue findings are frequently encountered on CT or MR imaging of the abdomen and pelvis. Many of these entities have specific imaging findings, for which a definitive diagnosis can be made without the need for further work up. These abdominal wall and spinal findings may be diagnostically challenging for sub-specialized abdominal radiologists who are unfamiliar with their appearance and appropriate management. This review article describes and illustrates pathognomonic or characteristic abdominal wall and spinal pathologies, which reside outside the abdominopelvic cavity. The cases selected all have findings that allow a confident diagnosis without further imaging or intervention. The cases presented include myonecrosis, intramuscular abscess, myositis, iliopsoas bursitis, Morel-Lavallée lesion, hydrocele of canal of Nuck, Klippel Trenaunay Weber syndrome, neurofibroma with target sign, perineural cysts, filum terminale lipoma, calvarial bone flap, transverse rectus abdominis muscle (TRAM) flap, liposuction, and hidradenitis suppurativa, among others. Although not all-encompassing, this paper will help abdominal radiologists to accurately diagnose a variety of abdominal and pelvic extra-cavitary soft tissue pathologies by identifying key radiologic findings.

Disorders of Secondary Neurulation : Mainly Focused on Pathoembryogenesis

Recent advancements in basic research on the process of secondary neurulation and increased clinical experience with caudal spinal anomalies with associated abnormalities in the surrounding and distal structures shed light on further understanding of the pathoembryogenesis of the lesions and led to the new classification of these dysraphic entities. We summarized the changing concepts of lesions developed from the disordered secondary neurulation shown during the last decade. In addition, we suggested our new pathoembryogenetic explanations for a few entities based on the literature and the data from our previous animal research. Disordered secondary neurulation at each phase of development may cause corresponding lesions, such as failed junction with the primary neural tube (junctional neural tube defect and segmental spinal dysgenesis), dysgenesis or duplication of the caudal cell mass associated with disturbed activity of caudal mesenchymal tissue (caudal agenesis and caudal duplication syndrome), failed ingression of the primitive streak to the caudal cell mass (myelomeningocele), focal limited dorsal neuro-cutaneous nondisjunction (limited dorsal myeloschisis and congenital dermal sinus), neuro-mesenchymal adhesion (lumbosacral lipomatous malformation), and regression failure spectrum of the medullary cord (thickened filum and filar cyst, low-lying conus, retained medullary cord, terminal myelocele and terminal myelocystocele). It seems that almost every anomalous entity of the primary neural tube may occur in the area of secondary neurulation. Furthermore, the close association with the activity of caudal mesenchymal tissue in secondary neurulation involves a wider range of surrounding structures than in primary neurulation. Although the majority of the data are from animals, not from humans and many theories are still conjectural, these changing concepts of normal and disordered secondary neurulation will provoke further advancements in our management strategies as well as in the pathoembryogenetic understanding of anomalous lesions in this area.

Structured MRI reporting in spinal dysraphism

Magnetic resonance evaluation of spinal dysraphism can be confusing for inexperienced radiologists and a detailed, step-by-step evaluation of the normal and abnormal imaging findings can help garner the diagnosis. The purpose of this article is to review the existing literature and to provide a comprehensive, structured, template checklist-style format for reporting spinal dysraphism that can help inexperienced radiologists to systematically analyze and report all the significant and ancillary findings in cases of spinal dysraphism and efficiently communicate the findings to the treating physician/surgeon.

Sindrome del midollo fissato o «Tethered cord»

Il «Tethered Cord» è una malformazione congenita polimorfa the insorge a partire dalla 6° settimana di vita embrionale. II quadro anatomo-radiologico è caratterizzato da un cono midollare ancorato in posizione anomala, per lo più estremamente bassa, da alcune forme di anomalie intradurali, e si inquadra frequentemente nell'ambito della sequenza malformativa di uno stato disrafico.

Il miglioramento prodotto dalla TC e dalla mielo-TC nella neurodiagnostica dei disrafismi spinali è stato ulteriormente incrementato dall'avvento della risonanza magnetica. Anche se quest'ultima consente frequentemente un inquadramento completo, in alcuni casi l'integrazione con mielo-TC permette una valutazione più precisa dell'estensione e dei rapporti delle varie componenti la malformazione.

Tuttavia alcuni aspetti della malformazione possono restare poco chiari, ancora insoluto appare il problema del riconoscimento del cono midollare dal filum terminale ispessito in alcune forme di «Tethered Cord». In questi casi tale difficoltà si riscontra anche in sede operatoria, pur utilizzando tecniche microchirurgiche. Proponiamo pertanto di definire l'unità anatomica Cono Midollare - Filum Terminale ispessito morfologicamente indistinti: «Struttura neurofibrosa».

The effect of flexion on the level of termination of the dural sac in paediatric patients

SUMMARY

Although the anatomy of the spinal cord and its associated structures have been well defined, the effects of body position relevant to neuraxial blockade have not been elucidated. This study was designed to determine the effect of body position on the end of the dural sac in children. After induction of anaesthesia, ultrasound examination was performed to evaluate the location of the dural sac end in the lateral position with a straight back and knee, and in the lateral position with the knees, legs, and neck flexed. The level of the end of the dural sac was determined in relation to the vertebrae. Our data demonstrate that the dural sac shifts significantly cephalad in the lateral flexed position used for neuraxial blockade (p < 0.001). These results suggest that the safety margin to avoid dural puncture during hiatal or S2-3 approach for caudal block can be increased in younger children.

Ultrasound measurement of lumbosacral spine in children

The aim of this study was to establish normal ultrasound measurements of lumbosacral spine in children as a screening assessment of tethered cord or postoperative retethering of cord. Sonography of lumbosacral spine was performed in 108 neurologically normal children (mean age = 2.1 years) using 5- to 12-MHz linear transducer. M-mode was applied at the posterior and anterior subarachnoid spaces just below the conus medullaris and at the L(5)/S(1) dural sac to document cerebrospinal fluid pulsation of the cauda equina. The oscillation rate and amplitude were measured. Sixteen children with spinal cord anomalies (6 with low tethered cord and 10 postoperative cases of low tethered cord) were also examined. The mean posterior/anterior subarachnoid spaces of normal children were 2.6 mm/1.8 mm at the terminal dural sac. The mean oscillation amplitude and rate of the cauda equina were 0.52 mm and 121/min at the L(5)/S(1) dural sac. The oscillation amplitude at this level demonstrated a statistically significant difference between normal and abnormal groups. In conclusion, we recommend taking the fifth percentile of the normal oscillation amplitude at the L(5)/S(1) dural sac as a reference. Any oscillation amplitude of less than 0.3 mm in a symptomatic patient should alert the clinician to possible cord abnormality, cord tethering, or retethering in postoperative cases.

Surgical treatment of the retethered spinal cord after repair of lipomyelomeningocele

In a series of 75 patients with surgically treated lipomyelomeningoceles, the neurological condition of six patients deteriorated 6 months to 14 years after the operation due to repeat tethering of the spinal cord. The tethering resulted from postoperative dense adhesion between the cord and the overlying dura mater. Two of the six patients underwent conventional repeat untethering procedures, and the remaining four were successfully treated with a new surgical technique developed by the authors to prevent such dural adhesion. For this procedure, after complete untethering of the spinal cord, the lumbosacral cord is retained in the center of the dural sac by fine stay sutures between the pia mater of the conus medullaris and the ventral dura mater. In addition, the dura mater is tacked to the posterior arch which is reconstructed with bone grafts at one or two bifid vertebral levels. During a postoperative follow-up period of 1 to 3 years, no further deterioration has been observed and magnetic resonance studies have demonstrated a space filled with cerebrospinal fluid (CSF) around the lumbosacral cord. The authors conclude that long-term observation, both neurological and radiological, is essential even after successful repair of a lipomyelomeningocele. This new surgical procedure can maintain a CSF bath around the lumbosacral cord, thus preventing dural adhesion. Application of this technique will hopefully be beneficial in lipomyelomeningocele patients with a high risk of cord retethering after initial repair.

Occult spinal dysraphism: neuroradiological study

We present a retrospective study of occult spinal dysraphism in 47 children aged 0 to 14 years, all studied with plain X-rays, 60% with CT and myelo-CT, and 40% with MR. We consider the classification and grading of these malformations, clinical, neuroradiological patterns, and indications for surgery. In the light of our findings and of the published data MR emerges as the key investigation. Only in a few cases of great anatomical complexity is it now necessary to perform CT and myelo-CT as well. A case in point is when the conus and thickened filum terminale are inextricably bound together and can no longer be considered separate structures. We propose the term "neurofibrous structure" to define the conus-thickened-filum-terminale unit when these structure are no longer distinguishable.

Occult spinal dysraphism. Case report and review of the literature

This case report and review of the literature is presented to create a greater diagnostic awareness of occult spinal dysraphism. Early recognition is based upon an understanding of this congenital anomaly and its variable presentations. These most commonly include abnormal gait, various cutaneous manifestations, particularly subcutaneous lipomata, and less frequently urological complaints. Surgical intervention, to arrest disease progression, is the primary mode of treatment, and functional improvement is variable. Long-term prognosis is dependent upon severity of neurologic deficits prior to surgery and the type of lesion found intraoperatively. Familial occurrence has been reported and genetic counseling may be an important preventive measure. Recent radiologic investigations have been concerned with the use of ultrasonography in screening infants at risk.

Surgically confirmed myelographic classification of congenital intraspinal lipoma in the lumbosacral region

Twenty-four cases of histologically confirmed congenital intraspinal lipoma of the lumbosacral region were studied by means of myelography with metrizamide. The findings were compared with intraoperative observations. Myelography with metrizamide clearly revealed the detailed intrathecal structures and allowed a classification of intraspinal lipomas into four types, in terms of their insertion into the conus medullaris: dorsal type, either with direct or indirect (via an intrathecal stalk) insertion of the extrathecal lipoma into the dorsal aspect of the conus medullaris; caudal type; combined type; and filar lipoma. Based on our surgical experience in untethering and decompression of the lesions, the classification was found to be useful in designing a safe and effective surgical procedure which minimized all possible trauma to the intrathecal neural structures.