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A short correlative review is given of the light and electron microscopical features and histochemical reactions of dystrophic axons in the mature human CNS. Their ultrastruc- tural similarities to axonal changes in the disease entity of the neuroaxonal dystrophies and various experimental conditions are confirmed. The incidence of axonal spheroids in the gracile and cuneate nuclei and in the reticular zone of the substantia nigra was studied in 1450 consecutive autopsies and correlated with age and underlying disease process. Axonal dystrophy of posterior column nuclei and substantia nigra showed a significant age-dependancy without predilection for either sex. The incidence of dystrophic axons in the globus pallidus and other sites was also examined. No clear relationship of the severity and frequency of the involvement of gracile nucleus with any underlying disease was established, while axonal dystrophy in substantia nigra showed significant correlations to alcoholic encephalopathies and Parkinson’s syndrome, and a trend to negative relationship with presenile cerebral atrophies. In addition to the natural occurrence of dystrophic axons as a physiological, age-dependant phenomenon, these lesions may arise prematurely and to excess in a variety of natural and experimental disorders. The reported findings suggest that some metabolic factors are involved in the pathogenesis of dystrophic axonal changes. Relations to axonal dying-back processes are discussed.

T UlS is a report of two cases that illustrate the variability of the pain pathways in the spinal cord of some individuals. Standard textbooks of neuroanatomy 3,5,6 give descriptions and present diagrams indicating that the pain pathway in the spinal cord in man is a discrete bundle of fibers, known as the spinothalamic tract, located in the anterolateral funiculus and consisting of afferent neurons of the second order. Finely myelinated or unmyelinated dorsal root fibers that serve as pain conductors terminate in the gray matter almost at once after entering the cord. From cells in the posterior column of the gray matter fibers arise which, in man, cross to the opposite side of the cord in the anterior white commissure and ascend in the lateral spinothalamic tract to end in the thalamus. Unilateral section of this tract produces complete loss of pain and temperature sensations on the opposite side of the body, extending upward to a level one segment below the level of the lesion, because of the oblique crossing of the spinothalamic fibers. These and similar statements are the result of piecing together fragmentary bits of clinical and experimental facts obtained over a period of many years. Unfortunately, our knowledge of the pain pathways in the spinal cord is still far from exact and the dogmatic statements and diagrams to be found in most textbooks cannot be substantiated by clinical observations. White and Sweet 9 in their extensive monograph on pain have reviewed the knowledge accumulated to date on the pain pathways in man.

Cavernous hemangiomas are vascular hamartomatous malformations that affect the central nervous system. This pathology is frequently encountered in the cerebral hemispheres, cerebellum, and brainstem. Cavernous hemangiomas infrequently occur at the spinal level or relative to an intramedullary localization; extramedullary epidural sites are also sometimes affected by this pathology. We report an extradural, extramedullary, cavernous hemangioma with foramenal extension of the dorsal section and discuss the differential diagnosis with dorsal foramenal neurinoma. A 52-year-old woman was admitted with irritation and deficit symptoms radiating into the left D3 spinal root space. The first radiological diagnosis was of a foramenal neurinoma beginning at the D3 root. The presence of a heterogeneous MR signal in both T1 and T2 images led us to consider the differential diagnosis of a cavernous hemangioma lesion. The patient underwent microsurgical treatment with a far lateral extraforamenal approach. Symptoms quickly improved: pain and dysesthesia disappeared after surgery and only light hypoesthesia was found. We want to stress the importance of MR imaging in formulating a correct differential diagnosis with foramenal neurinoma and underline that microsurgical treatment with a far lateral extraforamenal approach allowed us to remove the lesion completely without affecting Denis's posterior column, the lamina, and the articular facet.

Due to complex pelvic geometry, percutaneous screw placement in the posterior acetabular column can pose a major challenge even for experienced surgeons. The present study examined the preformed bone stock of the posterior acetabular column in 260 hemipelvises. Retrograde posterior column screws were virtually implanted using iPlan® CMF (BrainLAB AG, Feldkirchen, Germany); maximal implant length, maximal implant diameter and angles between the screw trajectories and the reference planes anterior pelvic plane as well as the midsagittal plane were assessed for gender-specific differences. The virtual analysis of the preformed bone stock column showed two constrictions of crucial clinical importance. These were located 49.6 ± 3.4 (41.0–60.2) mm (inferior margin of acetabulum) and 77.0 ± 5.6 (66.5–95.3) mm (centre of acetabulum) from the entry point of the implant in men and respectively 43.7 ± 2.3 (38.3–49.3) mm as well as 71.2 ± 3.5 (63.5–79.99) mm in women (men vs. women: p

Background To date, there has been no adequate biomechanical model that would allow a quantitative comparison in terms of stability/stiffness between a corpectomy with the posterior column preserved and a total spondylectomy with the posterior column sacrificed. The objective of this study was to perform a biomechanical comparison of 360° stabilizations for corpectomy and total spondylectomy, using the human thoracolumbar spine. Methods Five human cadaveric thoracolumbar spines (T8-L2) were tested according to the following loading protocol: axial compression, flexion, extension, lateral bending to the right and left, and axial rotation to the right and left. This loading protocol was applied three times. Each specimen was tested intact, after corpectomy, and after total spondylectomy. The relative stiffness of each motion segment was determined for each test. Results There was no significant difference in stiffness after reconstruction of total spondylectomy versus corpectomy in our thoracolumbar model. Our construct consisted of an anterior cage and four-level pedicle screw instrumentation (two above and two below) and provided similar stiffness in both models. Despite the additional bone resection in a total spondylectomy versus corpectomy, the constructs did not differ biomechanically. Additionally, there was no significant difference in stiffness between the intact specimen and either reconstruction model. Conclusions A classic corpectomy, which leaves the posterior column intact, is no better in terms of stability/stiffness than a total spondylectomy carried out using a shorter cage, followed by compression using posterior instrumentation.

Background Percutaneous lag screw fixation is an alternative treatment for non-displaced or minimally displaced posterior column fractures. This study aims to explore new fluoroscopic views of the acetabulum for safe percutaneous insertion of posterior column lag screws. Methods Axial computed tomography (CT) scans were taken of sixteen embalmed adult cadavers. The axial CT images at the level of the middle height of the acetabulum were selected. The angle (angle α) between the posterior cortex of the posterior column (PCPC) and the line intersecting the axial plane and the coronal plane, and the angle (angle β) between the medial wall and the line intersecting the axial plane and the sagittal plane were identified and measured. Tangential views of the PCPC and medial wall were obtained by referencing the measured angles. A lag screw was inserted into the posterior columns of the sixteen pelvic specimens under fluoroscopic guidance using an iliac oblique view and the two tangential views. CT scans were performed to evaluate the lag screw position. Axial CT images of 52 volunteers were obtained and the angles α and β were measured following the same methods used for the cadaveric specimens. Results The angles α and β for the specimens were 29.3±2.8.1 and 8.1±1.4 degrees, respectively. On the tangential view of the PCPC, the posterior cortex appears as a nearly straight line between the lesser and greater sciatic notches. On the tangential view of the medial wall, the medial wall appears as a distinct straight line. Using these radiographic images, the lag screws were inserted into the posterior columns of bony pelvic specimens. Screw placement was confirmed by CT, and found to be fully intraosseous in all cases without any cortical breaches. The angles α and β were 30.4±4.1 and 9.2±1.9 degrees for male volunteers and 28.5±3.7 and 7.7±1.8 degrees for female volunteers, significant difference in these angles between cadaveric specimens and human volunteers. Conclusion The tangential views of both the PCPC and medial wall can be obtained following the aforementioned methods The oblique iliac view and the two tangential views enable safe insertion of posterior column lag screws. Electronic supplementary material The online version of this article (doi:10.1186/1471-2474-15-303) contains supplementary material, which is available to authorized users.

Description of the pathway probably related to relief of pain and spasticity and improvement of cerebellar function induced by stimulation of posterior column is presented.

To the Editor. —The article on "Primary Lateral Sclerosis" by Younger et al,1in the December 1988 issue of theArchives, lists the following as part of the criteria: "Symptoms were restricted to progressive gait disorder without pain, paresthesias, sphincter symptoms, history of optic neuritis, transverse myelitis or other neurological disorder." However, in Merritt'sTextbook of Neurology, seventh edition, edited by Dr Rowland (whose name is also on the article in theArchives), it states under primary lateral sclerosis, on page 552, "In contrast to ALS, upper motor neuron bladder dysfunction is common and posterior column loss may be seen." The question is, which criterion is correct?

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To the Editor.— Soon after the case reports appeared by Butler et al describing Lhermitte's sign as an early finding of cobalamin deficiency (1981;245:1059), a 77-year-old man came to our geriatric clinic complaining of "electric shock-like" dysesthesias in both upper extremities. The maneuver most likely to precipitate the dysesthesis was forward flexion of the head while using the upper extremities. A physical examination with special attention to the posterior column function was unremarkable. The patient's hemoglobin level was 13.5 g/ dL, and the mean corpuscular volume was 102 femtoliters. There was no hypersegmentation of polymorphonuclear cells. The serum cobalamin level was depressed at 84 pg/dL (normal, 120 to 270 pg/dL), and a repeated test confirmed that the patient's level was well below the 95% confidence limit for the test. A Schilling's test showed normal absorption of crystalline cyanocobalamin Co 57. Treatment with parenterally administered cyanocobalamin alleviated the patient's symptoms. This

We studied position sense at the ankle in 22 normal subjects to develop a functionally meaningful method of identifying mild position sense loss in individuals with suspected posterior column disease. Subjects were asked to match the angular displacement of a passively positioned reference foot. The subjects tried to improve performance by training sessions and visual feedback during the task. The subjects made accurate matches over a wide range of positions, with an average error of about 3 degrees. These methods can be used to provide a sensitive assessment of proprioception.

"Complete" fracture-dislocation of the thoracic spine without neurologic deficit, a rarely described injury, occurred in a 29-year-old coal miner. Partial lesions or those without neurologic deficit may be associated with spontaneous decompression. Gross translational displacement of one vertebrae on another generally compresses interposed neural structures between the columns and/or fragments. Multiple pedicular fractures or posterior column disruption from the displaced anterior column functionally widens the neural canal, even with vertebral bodies side by side. The rib cage stabilizes the thoracic spine, decreasing the risk of neurologic injury. Although many surgeons proclaim the advantages of early open reduction and internal fixation, reduction may not always be necessary in this type of severe injury. Reduction entails highly significant risks, especially in neurologically uncompromised individuals with severe thoracic displacement.

Thirty-three persons in the Schut-Swier kindred at risk for autosomal dominant olivopontocerebellar degeneration have been examined and nine new cases identified. These affected individuals manifested severe cerebellar deficits; abnormalities of cortical, bulbar, and spinal motor neurons; and posterior column dysfunction. Cerebellar biopsy material from two patients revealed extensive progressing loss of Purkinje cells, degeneration of cortical afferents, and variable loss of granule cells. Vermiform tubules that resemble paramyxovirus nucleocapsids were found in association with crystalline inclusions in both biopsy specimens.

Until basic knowledge of fracture anatomy and stability includes experiments with comminuted anterior column injuries, posterior column injuries, and these injuries in combination with ligament and capsular injuries, and until the long-term implications of the long fusion in an otherwise healthy patient are fully known, clinicians making decisions about individual patients must assemble all the variables that bear on the patient's ability to heal and become fully functional again before making a decision about surgical stabilization of the thoracolumbar fracture. An assessment of plain roentgenograms, tomograms, and CAT scans and an understanding of the anatomy of the fracture site provide essential but insufficient data for clinical decisions about patients.

A 69-year-old woman with severe folate deficiency presented a clinical picture closely resembling that seen in classical prenicious anemia with neurologic involvement: megaloblastic anemia, dementia, impairment of posterior column functions, absent reflexes, and bilateral Babinski signs. All these abnormalities were resolved with folic acid therapy.

Introduction Since the original description of Charcot 1 nearly a century ago, hundreds of papers have been written on amyotrophic lateral sclerosis (ALS). The pathologic lesions of ALS have been described in the classical case as progressive degeneration and loss of cells in the anterior horns of the spinal cord, in the motor nuclei of the brain stem, and, in many instances, in the Betz cells of the cortex. Demyelination of the lateral columns is generally present, but is not necessarily limited to the corticospinal and corticobulbar fibers 2 ; posterior column demyelination, which has also been observed on occasion, 3,4 has, however, not been associated with any obvious sensory impairment. The phenomenal incidence of ALS in the Mariana Islands of the Western Pacific, and particularly on Guam, has evoked special attention during the past 10 years because of the geographical isolation and the familial aggregation of the disease among the

Amyotrophic lateral sclerosis, correctly regarded as a disease of the motor system, occasionally involves other neural structures, and cases have been recorded in which it was associated with mental symptoms 1 and sensory disturbances of both peripheral 2 and central nature. The question always arose whether the changes in the sensory pathways formed part of the picture of amyotrophic lateral sclerosis or were chance associations in the course of Charcot's disease. Another question is whether or not the degeneration of the pyramidal tract, posterior column and anterior horn cells is the result of a combined system disease, possibly on the basis of pernicious anemia. The following two cases in which degeneration of the posterior columns was present in clinically and pathologically typical syndromes of amyotrophic lateral sclerosis illustrate once more the occurrence of sensory disturbances in the "pure" motor syndrome. REPORT OF CASES Case 1. —M. F., a man aged

THE BROWN-SEQUARD syndrome represents a turning point in the history of neurophysiology.1-3Before Charles Edouard Brown-Sequard performed his classical experiments in the mid-19th century, the doctrines of Sir Charles Bell were dominant and all sensory impulses were believed to ascend the spinal cord ipsilaterally in the posterior column. Crossing to the opposite side was believed to occur only when the sensory impulses reached the brain. Brown-Sequard, the son of a Frenchwoman and an American sea captain, pursued his career as a physician and investigator mainly in Paris but also in the United States. By demonstrating that hemisection of the cord in animals produces sensory loss on the opposite side of the body with retention of sensation on the ipsilateral side, he challenged the idea that the posterior column is the sole sensory pathway and provided concrete evidence of sensory decussation in the spinal cord. Observation of human cases of

Incomplete hemilateral injuries of the spinal cord in the cervical region, with the resulting sensory and motor manifestations, are uncommon, and most often are the result of indirect violence—fracture dislocation of the vertebrae. In the World War, shrapnel and sharp, irregular shell fragments sometimes caused traumatic partial hemisection of the spinal cord by direct violence. Both of these, however, rarely cause strictly unilateral lesions. Stab wounds of the spinal cord are rare and give the most circumscribed and discrete lesions, and hence the most limited and definite sensory dissociation along with localized motor manifestations. The symptom-complex of partial hemisection differs from the Brown-Sequard syndrome of complete hemisection in that in the former the contralateral sensory loss is limited to pain and temperature senses, and there are no signs of disturbance of posterior column sensation. Hyperpathic sensation (heightened feeling tone), so well described by Foerster, 1 in which there is loss

To the Editor: —Nearly three-fourths of a century ago Longet, by very careful experimental research, concluded that sensory impressions were conducted solely by the posterior column of the spinal cord to the brain, and in his day this theory was generally accepted. Soon after Longet, or in 1823, Bellingeri demonstrated by experiments on living animals that sensory impressions were conducted to the brain through the gray matter of the cord exclusively. Flint, in his text-book, p. 678, makes the following inquiries: 1. Does or does not the white substance of the posterior column of the cord conduct sensory impressions to the brain? 2. Does the entire substance of the cord act as a conductor of sensibility? 3. Does both the gray matter of the cord and the white substance of the posterior column act as conductors, or does either one act to the exclusion of the other? "These questions," he

This case is reported because of its uniqueness and because of the emphasis laid on an important principle in the economy of the nervous system. That is, when the balance between two opposing systems is interfered with by disease, the clinical picture is so modified that it may lose one or several of its characteristic qualities. In this case a parkinsonian syndrome occurred without rigidity of muscles and without the characteristic masklike facies. The presence of lesions in the posterior column as a result of pernicious anemia so decreased the tonic qualities of the neuromuscular system that although a lesion was postulated in the striate system no rigidity was found and the muscles were hypotonic. From the series reported by Ahrens, 1 Weil, 2 Wilkinson 3 and Woltman 4 and the recent article by Goldhamer, Bethell, Isaacs and Sturgis, 5 it is agreed that about 80 to 90 per cent

The functional significance of the nucleus dorsalis, its relationship to incoming fibers and the course and termination of the fibers arising from its cells have been the subject of controversial discussions since Clarke's 1a description of the nucleus in 1851. It was early demonstrated that the nerve endings ramifying about the cells of Clarke's column come from fibers of the dorsal nerve roots which swing into the posterior column. These fibers were interpreted by Gaskell 2 as being visceral rami. He showed that the visceral rami were limited to three regions of the central nervous system: (1) a cervicocranial region, (2) a thoracic region and (3) a sacral region. Then he pointed out that Clarke's column forms a discontinuous column, the cell groups of which correspond accurately to those regions. He said: "The connection of these fibers with this column of cells is to my mind proved conclusively by the

Purpose The purpose of this study is to analyze the morphology of the scapula with reference to the glenoid component implantation in reversed shoulder prosthesis, in order to improve primary fixation of the component. Methods Seventy-three 3-dimensional computed tomography of the scapula and 108 scapular dry specimens were analyzed to determine the anterior and posterior length of the glenoid neck, the angle between the glenoid surface and the upper posterior column of the scapula and the angle between the major craneo-caudal glenoid axis and the base of the coracoid process and the upper posterior column. Results The anterior and posterior length of glenoid neck was classified into two groups named "short-neck" and "long-neck" with significant differences between them. The angle between the glenoid surface and the upper posterior column of the scapula was also classified into two different types: type I (mean 50°–52°) and type II (mean 62,50°–64°), with significant differences between them (p < 0,001). The angle between the major craneo-caudal glenoid axis and the base of the coracoid process averaged 18,25° while the angle with the upper posterior column of the scapula averaged 8°. Conclusion Scapular morphological variability advices for individual adjustments of glenoid component implantation in reversed total shoulder prosthesis. Three-dimensional computed tomography of the scapula constitutes an important tool when planning reversed prostheses implantation.

Introduction The neurological manifestation of vitamin B12 deficiency can occur as a result of peripheral nerve pathology or lateral and posterior column involvement, also known as “sub-acute combined degeneration”. This case report demonstrates an unusual presentation of SCD with normal B12 level. Case presentation A 39-year-old man was referred to the outpatient neurology clinic with a two month history of distal upper extremities numbness and fine motor movement difficulties. Initial vitamin B12 level was normal. A repeat MR imaging of the cervical and thoracic spine showed extensive posterior cervical cord flame-shaped lesions. His repeat vitamin B12 level was 41 pg/ml (normal; 200 ph/ml). He received monthly injections of vitamin B12. After six months his symptoms were resolved and his repeat spinal MRI showed resolution of the previous lesions. Conclusion We recommend that every patient presenting with numbness and lesions on a spinal MR imaging should have their vitamin B12 level checked.