Relationship Between the Development of the Spinal Canal and the Etiopathogenesis of Lumbar Spinal Stenosis

INTRODUCTION: The presence of a pre-existing narrow spinal canal may have an important place in the ethiopathogenesis of lumbar spinal stenosis. By consequence the study of the development of the spinal canal is crucial. The first goal of this work is to do a comprehensive literature search and to give an essential view on the development of spinal canal and its depending factors studied until now. The second goal is to give some considerations and hypothesize new leads for clinically useful researches. MATERIALS AND METHODS: A bibliographical research was executed using different search engines: PubMed, Google Schoolar ©, Ovid ® and Web Of Science ©. Free sources and avaible from the University of Lausanne (UNIL) and Centre Hospitalier Universitaire Vaudois (CHUV) were used. At the end of the bibliographic researches 114 references were found, 85 were free access and just 41 were cited in this work. Most of the found references are in English or in French. RESULTS AND DISCUSSION: The spinal canal is principally limited by the vertebrae which have a mesodermal origin. The nervous (ectodermal) tissue significantly influences the growth of the canal. The most important structure participating in the spinal canal growth is the neurocentral synchondrosis in almost the entire vertebral column. The fusion of the half posterior arches seems to have less importance for the canal size. The growth is not homogeneous but, depends on the vertebral level. Timing, rate and growth potentials differ by regions. Especially in the case of the lumbar segment, there is a craniocaudal tendency which entails a greater post-natal catch-up growth for distal vertebrae. Trefoil-shape of the L5 canal is the consequence of a sagittal growth deficiency. The spinal canal shares some developmental characteristics with different structures and systems, especially with the central nervous system. It may be the consequence of the embryological origin. It is supposed that not all the related structures would be affected by a growth impairment because of the different catch-up potentials. Studies found that narrower spinal canals might be related with cardiovascular and gastrointestinal symptoms, lower thymic function, bone mineral content, dental hypoplasia and Harris' lines. Anthropometric correlations found at birth disappear during the pediatric age. All factors which can affect bone and nervous growth might be relevant. Genetic predispositions are the only factors that can never be changed but the real impact is to ascertain. During the antenatal period, all the elements determining a good supply of blood and oxygen may influence the vertebral canal development, for example smoking during pregnancy. Diet is a crucial factor having an impact on both antenatal and postnatal growth. Proteins intake is the only proved dietetic relationship found in the bibliographic research of this work. The mechanical effects due to locomotion changes are unknown. Socioeconomic situation has an impact on several influencing factors and it is difficult to study it owing to numerous bias. CONCLUSIONS: A correct growth of spinal canal is evidently relevant to prevent not-degenerative stenotic conditions. But a "congenital" narrower canal may aggravate degenerative stenosis. This concerns specific groups of patient. If the size of the canal is highly involved in the pathogenesis of common back pains, a hypothetical measure to prevent developmental impairments could have a not- negligible impact on the society. It would be interesting to study more about dietetic necessities for a good spinal canal development. Understanding the relationship between nervous tissues and vertebra it might be useful in identifying what is needed for the ideal development. Genetic importance and the post-natal influences of upright standing on the canal growth remain unsolved questions. All these tracks may have a double purpose: knowing if it is possible to decrease the incidence of narrower spinal canal and consequently finding possible preventive measures. The development of vertebral canal is a complex subject which ranges over a wide variety of fields. The knowledge of this subject is an indispensable tool to understand and hypothesize the influencing factors that might lead to stenotic conditions. Unfortunately, a lack of information makes difficult to have a complete and satisfactory interdisciplinary vision.

Secular changes of spinal canal dimensions in Western Switzerland: a narrowing epidemic?

STUDY DESIGN: Computed tomography-based anatomical study. OBJECTIVE: To study the secular changes in lumbar spinal canal dimensions. SUMMARY OF BACKGROUND DATA: Development of symptomatic lumbar spinal stenosis, among other factors, is related to the dimensions of the bony canal. The canal reaches its adult size early on in life. Several factors, including protein intake, may influence its final dimensions. As with increases in human stature from improvements of socioeconomic conditions, we hypothesized that adult bony canal size has also grown larger in recent generations. METHODS: This study analyzes computed tomographic reconstructions from 184 subjects performed for either trauma (n = 81) or abdominal pathologies (n = 103) and born either between 1940 and 1949 (n = 88) or 1970 and 1979 (n = 96). The cross-sectional area of the bony canal was digitally measured at the level of the pedicle (i.e., at a level not influenced by degenerative changes) for each lumbar vertebra. Intra- and interobserver reliability was assessed. RESULTS: Intra- and interobserver measurement reliability were excellent (interclass correlation coefficient = 0.87) and good (interclass correlation coefficient = 0.61), respectively. Contrary to our hypothesis, the 1940-1949 generation patient group exhibited larger lumbar canals at all levels as compared with the 1970-1979 group. Statistically this difference was highly significant (P < 0.001) and particularly pronounced in the trauma subgroup. CONCLUSION: Given that human stature evolution has stabilized and adult height is established during the first 2 years of long bone growth, it is possible that antenatal factors are responsible for this surprising finding. Maternal smoking and age may be possible explanations. This finding may have significant implications. An increasing number of patients may emerge with lumbar spinal stenosis as degenerative changes develop, putting a strain on health resources. Further studies in different population groups and countries will be important to further confirm this trend. LEVEL OF EVIDENCE: 3.

The Anatomy of the Thoracic Spinal Canal Investigated with Magnetic Resonance Imaging

BACKGROUND: We investigated, with magnetic resonance imaging, the distance of the dura mater to the spinal cord in patients without spinal or medullar disease at the 2nd, 5th, and 10th thoracic segments.METHODS: Fifty patients in the supine position underwent magnetic resonance imaging. Medial sagittal slices of the 2nd, 5th, and 10th thoracic segments were measured for the relative distances using the 1.5-T superconducting system (Gyroscan Intera, Philips Medical Systems, Best, the Netherlands). In 10 patients, the angles relative to the tangent at the insertion point on the skin were measured.RESULTS: The posterior dural-spinal cord distance is significantly greater at the midthoracic region (5th thoracic = 5.8 +/- 0.8 mm) than at the upper (2nd thoracic = 3.9 +/- 0.8 mm) and lower thoracic levels (10th thoracic = 4.1 +/- 1.0 mm) (P < 0.015). There were no differences between interspaces T2 and 110. There was no correlation between age and the measured distance between the dura mater and the spinal cord. The entry angle of the needle at T2 was 9.0 degrees +/- 2.5 degrees; at T5, 45.0 degrees +/- 7.4 degrees; and at T10, 9.50 degrees +/- 4.2 degrees.CONCLUSIONS: This study demonstrated that there is greater depth of the posterior subarachnoid space at the T2, T5, and T10 levels. The greater distance was found at T5. (Anesth Analg 2010;110:1494-5)

Air within the spinal canal in spontaneous pneumomediastinum

Spontaneous pneumomediastinum is an uncommon benign condition that is occasionally associated with air within the spinal canal. We describe a further case in a 14-year-old girl and suggest a classification system based on a detailed review of the previous literature. Forty-eight patients with spontaneous pneumomediastinum and intraspinal air accumulation (36 men and 12 women, age range 4-72 years, median age 18 years) were grouped into those with underlying lung disease (n = 13), those with other underlying etiologic factors (n = 22), and those arising spontaneously (n = 13). Neurologic symptoms or signs were noted in one case. The remaining cases were successfully managed conservatively. In spontaneous pneumomediastinum, accumulation of air within the spinal canal is self-limiting and benign. The same management is advised in spontaneous pneumomediastinum with and without intraspinal air accumulation.

Normative MR Cervical Spinal Canal Dimensions

Purpose To provide normal values of the cervical spinal canal and spinal cord dimensions in several planes with respect to spinal level, age, sex, and body height. Materials and Methods This study was approved by the institutional review board; all individuals provided signed informed consent. In a prospective multicenter study, two blinded raters independently examined cervical spine magnetic resonance (MR) images of 140 healthy volunteers who were white. The midsagittal diameters and areas of spinal canal and spinal cord, respectively, were measured at the midvertebral levels of C1, C3, and C6. A multivariate general linear model described the influence of sex, body height, age, and spinal level on the measured values. Results There were differences for sex, spinal level, interaction between sex and level, and body height, while age had significant yet limited influence. Normative ranges for the sagittal diameters and areas of spinal canal and spinal cord were defined at C1, C3, and C6 levels for men and women. In addition to a calculation of normative ranges for a specific sex, spinal level, age, and body height data, data for three different height subgroups at 45 years of age were extracted. These results show a range of the spinal canal dimensions at C1 (from 10.7 to 19.7 mm), C3 (from 9.4 to 17.2 mm), and C6 (from 9.2 to 16.8 mm) levels. Conclusion : The dimensions of the cervical spinal canal and cord in healthy individuals are associated with spinal level, sex, age, and height. © RSNA, 2013 Online supplemental material is available for this article.

Patient outcomes after laminotomy, hemilaminectomy, laminectomy and laminectomy with instrumented fusion for spinal canal stenosis: a propensity score-based study from the Spine Tango registry.

PURPOSE To compare patient outcomes and complication rates after different decompression techniques or instrumented fusion (IF) in lumbar spinal stenosis (LSS). METHODS The multicentre study was based on Spine Tango data. Inclusion criteria were LSS with a posterior decompression and pre- and postoperative COMI assessment between 3 and 24 months. 1,176 cases were assigned to four groups: (1) laminotomy (n = 642), (2) hemilaminectomy (n = 196), (3) laminectomy (n = 230) and (4) laminectomy combined with an IF (n = 108). Clinical outcomes were achievement of minimum relevant change in COMI back and leg pain and COMI score (2.2 points), surgical and general complications, measures taken due to complications, and reintervention on the index level based on patient information. The inverse propensity score weighting method was used for adjustment. RESULTS Laminotomy, hemilaminectomy and laminectomy were significantly less beneficial than laminectomy in combination with IF regarding leg pain (ORs with 95% CI 0.52, 0.34-0.81; 0.25, 0.15-0.41; 0.44, 0.27-0.72, respectively) and COMI score improvement (ORs with 95% CI 0.51, 0.33-0.81; 0.30, 0.18-0.51; 0.48, 0.29-0.79, respectively). However, the sole decompressions caused significantly fewer surgical (ORs with 95% CI 0.42, 0.26-0.69; 0.33, 0.17-0.63; 0.39, 0.21-0.71, respectively) and general complications (ORs with 95% CI 0.11, 0.04-0.29; 0.03, 0.003-0.41; 0.25, 0.09-0.71, respectively) than laminectomy in combination with IF. Accordingly, the likelihood of required measures was also significantly lower after laminotomy (OR 0.28, 95% CI 0.17-0.46), hemilaminectomy (OR 0.28, 95% CI 0.15-0.53) and after laminectomy (OR 0.39, 95% CI 0.22-0.68) in comparison with laminectomy with IF. The likelihood of a reintervention was not significantly different between the treatment groups. DISCUSSION As already demonstrated in the literature, decompression in patients with LSS is a very effective treatment. Despite better patient outcomes after laminectomy in combination with IF, caution is advised due to higher rates of surgical and general complications and consequent required measures. Based on the current study, laminotomy or laminectomy, rather than hemilaminectomy, is recommendable for minimum relevant pain relief.

Influência do estreitamento do canal vertebral e do tempo para a descompressão na recuperação locomotora de ratos

OBJETIVO: o objetivo deste trabalho foi estudar as consequências da lesão por contusão da medula espinhal, associada ao estreitamento do canal vertebral, no comportamento motor de ratos, avaliando-se o efeito do tempo para descompressão na recuperação neurológica dos animais. MÉTODOS: foram utilizados ratos Wistar machos (n=6 por grupo), subdivididos nos seguintes grupos experimentais: laminectomia (T9-T10, Grupo Controle), contusão por queda de peso (10 g de peso, 15 cm de altura), estreitamento do canal vertebral em 35% (hastes de policarbonato; espessura de 0,78 mm) e contusão associada ao estreitamento do canal vertebral. O grupo de lesão associada foi ainda subdividido em sem ou com descompressão 24 ou 72 horas após a cirurgia. Os animais foram sacrificados sete dias após os procedimentos cirúrgicos. A função locomotora dos animais foi avaliada por meio do teste do campo aberto, do teste do plano inclinado e pela aplicação da escala BBB, antes da cirurgia, 24 e 72 horas depois da cirurgia e após 7 dias do procedimento cirúrgico. RESULTADOS: a lesão por queda de peso e compressão da medula espinhal, bem como a lesão mista, prejudicaram o comportamento motor dos animais, sendo que a descompressão cirúrgica após 24 e 72 horas da cirurgia não melhorou a recuperação motora dos animais, como mostram os resultados da avaliação de campo aberto, no plano inclinado e pela escala BBB. Por outro lado, os animais que sofreram lesão medular por queda de peso apresentaram melhores escores na escala BBB e ângulos maiores no plano inclinado do que aqueles que sofreram lesão por estreitamento do canal vertebral ou lesão mista. CONCLUSÕES: a lesão por queda de peso ou estreitamento do canal vertebral provocou alterações no comportamento motor dos animais, sendo que a descompressão não trouxe melhora funcional significativa.

Introducing a new MRI classification of lumbar spinal stenosis based on cross-sectional morphology of the dural sac : 37

Introduction: Measures of the degree of lumbar spinal stenosis (LSS) such as antero-posterior diameter of the canal, and dural sac cross sectional area vary, and do not correlate with symptoms or results of surgery. We created a grading system, comprised of seven categories, based on the morphology of the dural sac and its contents as seen on T2 axial images. The categories take into account the ratio of rootlet/ CSF content. Grade A indicates no significant compression, grade D is equivalent to a total myelograhic block. We compared this classification with commonly used criteria of severity of stenosis. Methods: Fifty T2 axial MRI images taken at disc level from 27 symptomatic LSS patients undergoing decompressive surgery were classified twice by two radiologists and three spinal surgeons working at different institutions and countries. Dural sac cross-sectional surface area and AP diameter of the canal were measured both at disc and pedicle level from DICOM images using OsiriX software. Intraand inter-observer reliability were assessed using Cohen's, Fleiss' kappa statistics, and t test. Results: For the morphological grading the average intra-and inter observer kappas were 0.76 and 0.69+, respectively, for physicians working in the study originating country. Combining all observers the kappa values were 0.57 ± 0.19. and 0.44 ± 0.19, respectively. AP diameter and dural sac cross-sectional area measurements showed no statistically significant differences between observers. No correlation between morphological grading and AP diameter or dural sac crosssectional areawas observed in 13 (26%) and 8 cases (16%), respectively. Discussion: The proposed morphological grading relies on the identification of the dural sac and CSF better seen on full MRI series. This was not available to the external observers, which might explain the lower overall kappa values. Since no specific measurement tools are needed the grading suits everyday clinical practice and favours communication of degree of stenosis between practising physicians. The absence of a strict correlation with the dural sac surface suggests that measuring the surface alone might be insufficient in defining LSS as it is essentially a mismatch between the spinal canal and its contents. This grading is now adopted in our unit and further studies concentrating on relation between morphology, clinical symptoms and surgical results are underway.

Transitional cell carcinoma of urinary bladder with metastasis in lumbar vertebrae and spinal cord compression in an ocelot(Leopardus pardalis)

This paper reports a case of nonpapillary and infiltrative transitional cell carcinoma (TCC) of the urinary bladder with metastasis of lumbar vertebrae and spinal cord compression in an adult female ocelot (Leopardus pardalis), from the Mato Grosso state, Brazil. The ocelot had pelvic limb paralysis and skin ulcers in the posterior region of the body and was submitted to euthanasia procedure. At necropsy was observed a multilobulated and irregular shaped, yellowish to white nodule in the urinary bladder. The nodule had a soft consistency and arised from the mucosa of the urinary bladder extending throughout the muscular layers and the serosa. Nodules of similar appearance infiltrating the vertebral column the at L6 and L7 vertebrae with corresponding spinal canal invasion were also observed. The histological evaluation showed epithelial neoplastic proliferation in the urinary bladder with characteristics of nonpapillary and infiltrative TCC, with positive immunohistochemical staining for pancytokeratin, and strong immunostaining for cytokeratin of low molecular weight, and weak or absent labeling for high molecular weight cytokeratin. This is the first report of TCC of urinary bladder in ocelot in Brazil.

Extra and intradural spinal Hemangioblastoma

Hemangioblastomas of the central nervous system (CNS) are low-grade highly vascularized tumors that may be sporadic or associated with Von Hippel-Lindau disease. Extradural hemangioblastomas are uncommon and those located extra and intradurally are even rarer. This study uses an illustrative case and literature review to discuss the difficulties to consider the correct diagnosis and to select the best surgical approach. A 57 years-old white male patient presented with myelopathy and right C5 radiculopathy. The images showed a lobulated, hourglass shaped, highly enhanced extra/intradural lesion that occupied the spinal canal and widened the C4-C5 right intervertebral foramen. Total resection of the intradural lesion was achieved through a posterior approach, but the extradural part could only be partially removed. Complete improvement was observed after four months of follow-up and the residual tumor has been followed up clinically and radiologically. Even though the preoperative impression was of a spinal schwannoma, the histopathological examination revealed grade I hemangioblastoma as per WHO. Despite their rarity, current complementary exams allow considering the diagnosis of hemangioblastoma preoperatively. That is essential to a better surgical planning in view of the particular surgical features of this lesion.

Incidence of spinal compressive lesions in chondrodystrophic dogs with abnormal recovery after hemilaminectomy for treatment of thoracolumbar disc disease: a prospective magnetic resonance imaging study

OBJECTIVE: To investigate causes of the lack of clinical improvement after thoracolumbar disc surgery. STUDY DESIGN: Case-control magnetic resonance imaging (MRI) study. ANIMALS: Chondrodystrophic dogs with acute thoracolumbar disc disease treated by hemilaminectomy: 10 that had no short-term clinical improvement and 12 with "normal" clinical improvement. METHODS: Dogs that had surgery for treatment of intervertebral disc extrusion (2003-2008) where thoracolumbar disc disease was confirmed by MRI were evaluated to identify dogs that had lack of clinical improvement after surgery. Ten dogs with delayed recovery or clinical deterioration were reexamined with MRI and compared with 12 dogs with normal recovery and MRI reexamination after 6 weeks (control group). RESULTS: Of 173 dogs, 10 (5.8%) had clinical deterioration within 1-10 days after surgery. In 8 dogs, residual spinal cord compression was identified on MRI. Bleeding was present in 1 dog. In 3 dogs, the cause was an incorrect approach and insufficient disc material removal. In 3 dogs, recurrence occurred at the surgical site. In 1 dog, the centrally located extruded material was shifted to the contralateral side during surgery. These 8 dogs had repeat surgery and recovery was uneventful. In 2 dogs, deterioration could not be associated with a compressive disc lesion. Hemorrhagic myelomalacia was confirmed by pathologic examination in 1 dog. The other dog recovered after 6 months of conservative management. CONCLUSION: Delayed postsurgical recovery or deterioration is commonly associated with newly developed and/or remaining compressive disc lesion. CLINICAL RELEVANCE: We recommend early MRI reexamination to assess the postsurgical spinal canal and cord, and to plan further therapeutic measures in chondrodystrophic dogs with delayed recovery after decompressive hemilaminectomy for thoracolumbar disc disease.

Zementaugmentation bei Wirbelmetastasen (Vertebro- und Kyphoplasie) [Cement injection for spinal metastases (vertebroplasty and kyphoplasty)]

Osteolytic lesions of the spine (metastasis, myeloma) can be treated extremely efficiently by percutaneous cement injection. The treatment should be restricted to osteolytic lesions of the vertebral body, and only if a relevant mechanical deterioration is present. If the pedicles and/or the lamina are involved and if there is compression of the spinal canal, the treatment is no longer appropriate. The surgical technique is similar to the treatment of osteoporotic fractures; however, there is definitely a higher risk for cement leakage and the clinical outcome is not as predictable as in osteoporotic fracture treatment. It is important to realize that cement injection per se has no impact on the tumor itself, but provides stability to the vertebral body. An osteolytic lesion without mechanical compromise does not need a vertebroplasty. Patients with tumorous lesions of the spine should be followed by an interdisciplinary team of spine surgeon, oncologist and radio-oncologist.

A rare case of a large spinal meningioma with mediastinal extension and malignant behavior classified histologically as benign

AIM To report a rare case of a spinal WHO grade I meningioma extending through intervertebral foramina C7 to D4 with an extensive mediastinal mass and infiltration of the vertebrae, and to discuss the malignant behavior of a tumor classified as benign. METHODS (Clinical Presentation, Histology, and Imaging): A 54-year-old man suffered from increasing lower back pain with gait difficulties, weakness and numbness of the lower extremities, as well as urge incontinence. CT scan of the thorax and MRI scan of the spine revealed a large prevertebral tumor, which extended to the spinal canal and caused compression of the spinal cord at the levels of C7 to D4 leading to myelopathy with hyperintense signal alteration on T2-weighted MRI images. The signal constellation (T1 with and without contrast, T2, TIR) was highly suspicious for infiltration of vertebrae C7 to D5. Somatostatin receptor SPECT/CT with (111)In-DTPA-D: -Phe-1-octreotide detected a somatostatin receptor-positive mediastinal tumor with infiltration of multiple vertebrae, dura, and intervertebral foramina C7-D4, partially with Krenning score >2. Percutaneous biopsies of the mediastinal mass led to histopathological findings of WHO grade I meningioma of meningothelial subtype. RESULTS (Therapy): C7 to D4 laminoplasty was performed, and the intraspinal, extradural part of the tumor was microsurgically removed. Postoperative stereotactic radiation therapy was done using the volumetric modulated arc therapy (VMAT) technique (RapidArc). No PRRNT with (90)Y-DOTA-TOC was done. CONCLUSIONS Due to the rare incidence and complex presentation of this disease not amenable to complete surgical resection, an individualized treatment approach should be worked out interdisciplinarily. The treatment approach should be based not only on histology but also on clinical and imaging findings. Close clinical and radiological follow-up may be mandatory even for benign tumors.

Increased intraoperative epidural pressure in lumbar spinal stenosis patients with a positive nerve root sedimentation sign

Purpose The sedimentation sign (SedSign) has been shown to discriminate well between selected patients with and without lumbar spinal stenosis (LSS). The purpose of this study was to compare the pressure values associated with LSS versus non-LSS and discuss whether a positive SedSign may be related to increased epidural pressure at the level of the stenosis. Methods We measured the intraoperative epidural pressure in five patients without LSS and a negative SedSign, and in five patients with LSS and a positive SedSign using a Codman TM catheter in prone position under radioscopy. Results Patients with a negative SedSign had a median epidural pressure of 9 mmHg independent of the measurement location. Breath and pulse-synchronous waves accounted for 1–3 mmHg. In patients with monosegmental LSS and a positive SedSign, the epidural pressure above and below the stenosis was similar (median 8–9 mmHg). At the level of the stenosis the median epidural pressure was 22 mmHg. A breath and pulse-synchronous wave was present cranial to the stenosis, but absent below. These findings were independent of the cross-sectional area of the spinal canal at the level of the stenosis. Conclusions Patients with LSS have an increased epidural pressure at the level of the stenosis and altered pressure wave characteristics below. We argue that the absence of sedimentation of lumbar nerve roots to the dorsal part of the dural sac in supine position may be due to tethering of affected nerve roots at the level of the stenosis.