Intervertebral Disc Lesions Research Articles

Deposition of ochronotic pigment in articular cartilage in alkaptonuria is initiated near the tidemark and progresses to the articular surface

Imagistic and histopathologic concordances in degenerative lesions of intervertebral disks M.I. Cevei, D.C. Stoicanescu, L.A. Lazar, E. Rosca Medical Rehabilitation Clinical Hospital Baile Felix, 1University of Oradea, Faculty of Medicine and Pharmacy, Oradea, Romania University of Medicine and Pharmacy “Victor Babes”, Department of Medical Genetics, Timisoara, Romania 1University of Oradea, Faculty of Medicine and Pharmacy, Oradea, Romania

Corticomotor excitability of back muscles is affected by intervertebral disc lesion in pigs

Morphological and behavioural changes in back muscles are common in back pain and injury. Recent data indicate a rapid reduction in the size of the multifidus, a deep back muscle, within 3 days of experimental intervertebral disc (IVD) injury in pigs. A reduced neural drive may contribute to this. We investigated changes in corticomotor excitability following IVD lesion by evaluation of the response of back muscles to electrical stimulation of the motor cortex. Motor evoked potentials (MEPs) were studied in 12 Swedish landrace pigs before injury, immediately after abdominal incision, immediately after L3-4 IVD lesion with a scalpel, and 15 min later. In two animals, responses were also evoked by descending volleys excited at the level of the mastoid processes (cervicomedullary evoked potentials) without motor cortex activation. In five animals, a sham procedure was followed without IVD lesion. MEPs were recorded in short (deep) and long (superficial) fibres of the multifidus at L3-5 on the lesioned side and at L4 contralaterally with intramuscular wire electrodes. Although the MEP amplitude increased in several muscles after incision, at 15 min after IVD lesion only the MEP amplitude of the deep L4 multifidus on the lesioned side was increased [36% (SD 15%), P < 0.05]. There were no changes in MEP amplitude after 15 min at adjacent or contralateral levels. The response to cervicomedullary stimulation reduced slightly. This suggests that the increased MEP amplitude was due to changes in cortical excitability. These data indicate that IVD lesion induces localized increases, and not decreases, in the excitability of cortical inputs to the deep paraspinal muscles that cross a lesioned disc.

MRI and discography in traumatic intervertebral disc lesions

In this study we evaluated magnetic resonance imaging (MRI) in trauma patients for assessing traumatised adjacent discs of fractured vertebrae before dorsoventral stabilisation. In a prospective study, MRI of 54 discs was performed with a 1.5-T MRI unit. The preoperative MRI with sagittal T1-W-SE and T2-W-TSE was compared to intraoperative discography, which was carried out on both intervertebral discs adjacent to the fractured vertebrae. Signal alterations, morphological changes in the adjacent discs, fractured vertebrae and associated ligament injuries were evaluated. In 47/54 (87%) of the intervertebral discs, the results of both imaging findings were concordant. The discs adjoining vertebral fractures were normal in 18 cases. Regarding the positive concordant imaging findings, MRI and discography revealed traumatised adjacent cranial and caudal discs in 22 discs. In 7 cases, only the cranial adjacent disc was affected. Moreover, 17 cases of intradiscal bleeding, 13 intraosseous herniations into the fractured vertebrae and 20 anuluar tears were visualised in MRI. Associated ligament injuries were detected in 18 cases. Findings were discordant in eight discs. In six discs, MRI was abnormal, demonstrating signal alterations suggestive of positive imaging findings, whereas discography demonstrated no disc injury. MRI failed to detect disc injury in two discs, whereas discography was positive, showing an irregular intradiscal contrast media distribution. MRI, as a non-invasive method for assessing fractures of the thoraco-lumbar spine, may detect traumatised adjacent intervertebral discs. MRI is superior to intraoperative discography. The performance of MRI of the thoraco-lumbar spine is recommended before dorsoventral stabilisation in trauma patients, as it can reveal additional preoperative information such as fractures, disc and associated ligament injuries.

Rapid Atrophy of the Lumbar Multifidus Follows Experimental Disc or Nerve Root Injury

Experimental study of muscle changes after lumbar spinal injury. To investigate effects of intervertebral disc and nerve root lesions on cross-sectional area, histology and chemistry of porcine lumbar multifidus. The multifidus cross-sectional area is reduced in acute and chronic low back pain. Although chronic changes are widespread, acute changes at 1 segment are identified within days of injury. It is uncertain whether changes precede or follow injury, or what is the mechanism. The multifidus cross-sectional area was measured in 21 pigs from L1 to S1 with ultrasound before and 3 or 6 days after lesions: incision into L3-L4 disc, medial branch transection of the L3 dorsal ramus, and a sham procedure. Samples from L3 to L5 were studied histologically and chemically. The multifidus cross-sectional area was reduced at L4 ipsilateral to disc lesion but at L4-L6 after nerve lesion. There was no change after sham or on the opposite side. Water and lactate were reduced bilaterally after disc lesion and ipsilateral to nerve lesion. Histology revealed enlargement of adipocytes and clustering of myofibers at multiple levels after disc and nerve lesions. These data resolve the controversy that the multifidus cross-sectional area reduces rapidly after lumbar injury. Changes after disc lesion affect 1 level with a different distribution to denervation. Such changes may be due to disuse following reflex inhibitory mechanisms.

MRI and discography in traumatic intervertebral disc lesions

In this study we evaluated magnetic resonance imaging (MRI) in trauma patients for assessing traumatised adjacent discs of fractured vertebrae before dorsoventral stabilisation. In a prospective study, MRI of 54 discs was performed with a 1.5-T MRI unit. The preoperative MRI with sagittal T1-W-SE and T2-W-TSE was compared to intraoperative discography, which was carried out on both intervertebral discs adjacent to the fractured vertebrae. Signal alterations, morphological changes in the adjacent discs, fractured vertebrae and associated ligament injuries were evaluated. In 47/54 (87%) of the intervertebral discs, the results of both imaging findings were concordant. The discs adjoining vertebral fractures were normal in 18 cases. Regarding the positive concordant imaging findings, MRI and discography revealed traumatised adjacent cranial and caudal discs in 22 discs. In 7 cases, only the cranial adjacent disc was affected. Moreover, 17 cases of intradiscal bleeding, 13 intraosseous herniations into the fractured vertebrae and 20 anuluar tears were visualised in MRI. Associated ligament injuries were detected in 18 cases. Findings were discordant in eight discs. In six discs, MRI was abnormal, demonstrating signal alterations suggestive of positive imaging findings, whereas discography demonstrated no disc injury. MRI failed to detect disc injury in two discs, whereas discography was positive, showing an irregular intradiscal contrast media distribution. MRI, as a non-invasive method for assessing fractures of the thoraco-lumbar spine, may detect traumatised adjacent intervertebral discs. MRI is superior to intraoperative discography. The performance of MRI of the thoraco-lumbar spine is recommended before dorsoventral stabilisation in trauma patients, as it can reveal additional preoperative information such as fractures, disc and associated ligament injuries.

Sacralization: an aetiological factor in lumbar intervertebral disk lesions, and a cause of misleading focal signs.

Sacralization: an aetiological factor in lumbar intervertebral disk lesions, and a cause of misleading focal signs.

Lesions of the cervical intervertebral disc. By R. Glen Spukling, M.D., Professor of Neuro-surgery, University of Louisville School of Medicine, Louisville, Kentucky. 9½ × 6 in. Pp. 134 + xvi, with 41 illustrations. 1956. Springfield, Ill.: Charles C. Thomas. (Oxford: Blackwell.) 36s

Lesions of the cervical intervertebral disc. By R. Glen Spukling, M.D., Professor of Neuro-surgery, University of Louisville School of Medicine, Louisville, Kentucky. 9½ × 6 in. Pp. 134 + xvi, with 41 illustrations. 1956. Springfield, Ill.: Charles C. Thomas. (Oxford: Blackwell.) 36s Lesions of the Cervical Intervertebral Disc. By R GlenSpukling, M.D., Professor of Neuro-surgery, University of Louisville School of Medicine, Louisville, Kentucky. 9½ × 6 in. Pp. 134 + xvi, with 41 illustrations. 1956. Springfield, Ill.: Charles C. Thomas. (Oxford: Blackwell.) 36s. British Journal of Surgery, Volume 44, Issue 188, May 1957, Page 639, https://doi.org/10.1002/bjs.18004418838 Published: 05 December 2005

Myelography in lumbar intervertebral disk lesions a correlation with operative findings

Myelography in lumbar intervertebral disk lesions a correlation with operative findings

The mechanical effects of intervertebral disc lesions

Objective. To determine the mechanical effect of individual concentric tears, radial tears and rim lesions of the intervertebral disc anulus. Design. In vitro dynamic mechanical testing of sheep discs comparing the mechanical behaviour before and after lesion creation. Background. Structural changes to the disc in the form of anular lesions are a feature of disc degeneration and degeneration has been related to changes in the mechanical function of the disc. However, the effect of individual lesions is unknown. Methods. Fifteen ovine, lumbar disc body units were tested in flexion/extension, lateral bending and axial rotation. Concentric tears, radial tears and rim lesions were experimentally introduced and the motions repeated. The mechanical response after lesion creation was compared to the undamaged response. Results. It was found that an anterior rim lesion reduced the peak resistive moment produced by the disc in extension, lateral bending and axial rotation. Concentric tears and radial tears did not affect the peak resistive moment, however, radial tears reduced the hysteresis of response in flexion/extension and lateral bending. The neutral zone was not affected by the presence of disc lesions. Conclusions. These results show that rim lesions reduce the disc's ability to resist motion. Radial tears change the hysteresis of response indicating an altered stress distribution in the disc. Relevance These changes may lead to overloading of the spinal ligaments, muscles and zygapophysial joints, possibly damaging these structures. This suggests a mechanism for a cycle of degeneration that is instigated by small changes in the mechanical integrity of the intervertebral disc.

Fine-Needle Aspiration Biopsy of Vertebral and Intervertebral Disc Lesions

Abstract Background and Objectives.—Fine-needle aspiration biopsy (FNAB) is used extensively in the clinical workup of radiologically detected bony lesions. The aims of this study were to evaluate the diagnostic utility of FNAB of such radiologically detected vertebral and intervertebral disc lesions in patients with and without a known primary malignancy, to establish criteria for specimen adequacy, and to evaluate the diagnostic pitfalls. Design.—The cytologic material obtained by FNAB performed under computed tomographic guidance of 78 cases comprising 66 vertebral and 12 intervertebral disc lesions was reviewed and analyzed. The initial cytologic diagnosis was compared with the diagnosis after review in all 78 cases. Results.—Thirty-five cases (45%) were positive for malignancy, 1 case (1.3%) was suspicious for malignancy, 9 (11.5%) consisted of normal cellular elements with no evidence of malignancy, 21 (27%) were unsatisfactory/inadequate for diagnosis, and 12 (15.2%) were benign nonneoplastic lesions. Nonneoplastic lesions diagnosed included fracture callus, discitis/osteomyelitis, degenerative disc disease, and Paget disease. In 11 cases, FNAB gave the initial diagnosis of malignancy (8 occult carcinomas and 3 plasmacytomas). In 23 out of 36 cases with a clinical history of a known primary tumor, FNAB established the diagnosis of metastases, and in 1 case, a second primary was detected. Conclusions.—Fine-needle aspiration biopsy of radiologically suspected vertebral and intervertebral disc lesions in patients with a history of a known malignancy is useful to confirm the presence of metastases. In cases without any history of malignancy, FNAB can provide additional clues to aid in the subsequent workup and treatment of cases diagnosed with an unsuspected malignancy and other nonneoplastic lesions. Through assessment of the specimen adequacy, correct interpretation of the cytologic material available, and correlating with the clinical and radiologic findings, a definitive diagnosis can be made in most cases.

Fine-needle aspiration biopsy of vertebral and intervertebral disc lesions: specimen adequacy, diagnostic utility, and pitfalls.

c Background and Objectives.—Fine-needle aspiration biopsy (FNAB) is used extensively in the clinical workup of radiologically detected bony lesions. The aims of this study were to evaluate the diagnostic utility of FNAB of such radiologically detected vertebral and intervertebral disc lesions in patients with and without a known primary malignancy, to establish criteria for specimen adequacy, and to evaluate the diagnostic pitfalls. Design.—The cytologic material obtained by FNAB performed under computed tomographic guidance of 78 cases comprising 66 vertebral and 12 intervertebral disc lesions was reviewed and analyzed. The initial cytologic diagnosis was compared with the diagnosis after review in all 78 cases. Results.—Thirty-five cases (45%) were positive for malignancy, 1 case (1.3%) was suspicious for malignancy, 9 (11.5%) consisted of normal cellular elements with no evidence of malignancy, 21 (27%) were unsatisfactory/inadequate for diagnosis, and 12 (15.2%) were benign nonneoplastic lesions. Nonneoplastic lesions diagnosed included fracture callus, discitis/osteomyelitis, degenerative disc disease, and Paget disease. In 11 cases, FNAB gave the initial diagnosis of malignancy (8 occult carcinomas and 3 plasmacytomas). In 23 out of 36 cases with a clinical history of a known primary tumor, FNAB established the diagnosis of metastases, and in 1 case, a second primary was detected. Conclusions.—Fine-needle aspiration biopsy of radiologically suspected vertebral and intervertebral disc lesions in patients with a history of a known malignancy is useful to confirm the presence of metastases. In cases without any history of malignancy, FNAB can provide additional clues to aid in the subsequent workup and treatment of cases diagnosed with an unsuspected malignancy and other nonneoplastic lesions. Through assessment of the specimen adequacy, correct interpretation of the cytologic material available, and correlating with the clinical and radiologic findings, a definitive diagnosis can be made in most cases. (Arch Pathol Lab Med. 2001;125:1463‐1468)

Traumatic intervertebral disc lesion--magnetic resonance imaging as a criterion for or against intervertebral fusion.

Lesions of the intervertebral disc accompanying vertebral fractures are the subject of controversy and discussion regarding the extent and manner of surgical intervention. The question of when to perform disc resection and intervertebral fusion, in particular, has not been answered satisfactorily. In order to evaluate short- and medium-term lesions of the discoligamentous complex associated with thoracolumbar burst fractures, magnetic resonance images made after stabilisation and again after implant removal were compared. Between 1997 and 1998, 20 patients who had suffered thoracolumbar burst fractures (AO classification A3 and B1 [26]) underwent posterior reduction and stabilisation using a Universal Spine System (USS, Synthes, Switzerland) titanium internal fixator. The implant was removed after an average of 10 months. Magnetic resonance imaging (MRI) scans were performed 1 week after both operations, allowing the changes in a total of 40 intervertebral discs adjacent to the fractured vertebral body to be investigated. The analysis was based on signal intensity of the intervertebral disc in T2-weighted scans and on morphological criteria. A total of 81% of the discs with initially normal T2-weighted signal showed the same signal after implant removal; 5 discs with initially increased signal intensity in T2-weighted scans normalised, 5 showed a decrease in intensity and 3 suffered a partial loss of signal. Among the 9 discs with initially decreased T2-weighted signal, only one had normalised by the time the implant was removed. A total of 86% of the 14 morphologically intact discs retained their structural integrity. Of the 25 discs with minor defects, only one could be considered as intact after implant removal, 15 remained the same and 9 deteriorated in structure. No disruption of the fibrous ring or of the posterior longitudinal ligament was observed, nor was there any prolapse of intervertebral discs. When the intervertebral disk is intact and has normal morphology and a normal T2-weighted MRI signal, resection or fusion of the fracture adjacent discs appears unjustified. In our opinion, the results do not support the possibility of predicting degradation in those discs that showed an altered T2-weighted signal after the first operation.

Low back pain and the lumbar intervertebral disk: Clinical considerations for the doctor of chiropractic

Background: Low back pain exists in epidemic proportions in the United States. Studies that demonstrate innervation to the intervertebral disk provide evidence that may account for instances of discogenic low back pain encountered in general medical and chiropractic practice. Many patients and health care practitioners believe that intervertebral disk lesions require surgery as the only method of treatment that will result in satisfactory outcome. Surgery rates vary widely across geographic regions. Only one randomized prospective study exists that compares surgical and nonsurgical treatment; it demonstrated essentially equal outcomes in the long run. Objective: To review specific aspects of the examination, history, imaging, and treatment of patients with suspected intervertebral disk lesions and to provide guidelines for conservative management, imaging, and relative and absolute indications for surgical referral. Data Sources: Review articles, texts, and original articles from indexed refereed sources that discuss the lumbar intervertebral disk in regard to patient history, physical examination, imaging, treatment, and referral for surgery. Results: Patients with low back pain who do not present with so-called red flags (fever, history of cancer, unexplained weight loss, urinary tract infection, intravenous drug use, saddle anesthesia, or prolonged use of corticosteroids) may be treated initially with conservative methods. Imaging studies are helpful in determining the patient's diagnosis, and computed tomography, magnetic resonance imaging, or other special imaging studies should be ordered judiciously. The only prospective, randomized study of conservative versus surgical management of herniated lumbar intervertebral disk lesions indicates both methods provide adequate outcome in the long run. Little consensus exists on the best method of management for patients with intervertebral disk lesions without absolute indications for surgery. Conclusion: Patients should be screened for “red flags” to determine whether they are candidates for conservative treatment. Magnetic resonance imaging is perhaps the most practical imaging study for evaluation of lumbar disk lesions because it involves no use of ionizing radiation and because magnetic resonance imaging has other advantages over computed tomographic scanning such as excellent delineation of soft tissue structures, direct multiplanar imaging, and excellent characterization of medullary bone. Provocation computed tomography-diskography is an invasive procedure and should be reserved for patients with normal magnetic resonance imaging findings and continuing severe pain who have not been helped by conservative treatment attempts and for whom surgical intervention is contemplated. Both conservative and surgical interventions have been shown to be effective in the treatment of discogenic and radicular pain syndromes. (J Manipulative Physiol Ther 1999;22:96–104).

William Jason Mixter (1880-1958). Ushering in the "dynasty of the disc".

William Jason Mixter was born in 1880 and graduated from the Harvard Medical School class of 1906. Like his father, Mixter was a prominent surgeon at the Massachusetts General Hospital, and in 1911 the two shared the job of overseeing all neurosurgery at that institution. By the early 1930s, W. J. Mixter was considered to be one of the nation's leading experts in spinal surgery, and he went on to become the first chief of the neurosurgery department at Massachusetts General Hospital. He served in the U. S. Army in both world wars and was actively involved in his local church community in Boston for many years. In 1934, at the age of 54, Mixter and Joseph S. Barr published an article on the intervertebral disc lesion in the New England Journal of Medicine. That article fundamentally changed the popular understanding of sciatica at that time, and for this work Mixter is generally credited by his contemporaries as being the man who best clarified the relation between the intervertebral disc and sciatica. Mixter and Barr's landmark report helped to establish surgery's prominent role in the management of sciatica at the time. Over the next few decades, discectomy surgery increased in popularity tremendously, and some refer to that period as the "dynasty of the disc."

Gene expression of noncollagenous bone matrix proteins in the limb joints and intervertebral disks of the twy mouse.

The twy (tiptoe walking Yoshimura) mouse is an autosomal recessive mutant manifesting multiple osteochondral lesions characterized by pathologic calcium deposition. To elucidate the pathophysiology of the limb joint lesions and the intervertebral disk lesions of the twy mouse, we assessed the mRNA expression of noncollagenous bone matrix proteins such as osteocalcin, osteonectin, osteopontin, and matrix Gla protein (MGP) by in situ hybridization, but only expression of MGP was observed in association with the pathologic calcium deposits in twy mice. Mild degeneration and abnormal growth of the cartilage in contact with the joint capsule was observed at 5 weeks in the articular cartilage of the ankle joint of the twy mouse, and MGP gene expression was observed at the same time. Simultaneous growth of synovial membrane cells and relatively undifferentiated articular cartilage cells in the knee joint, and of cartilage-like cells near the insertion of the cruciate ligament was observed in the twy mouse, and MGP gene expression was found to be present at the same time. Hypertrophy of abnormally proliferated chondrocyte-like cells, which are different from fibrocartilaginous cells of the annulus fibrosus, was observed in the intervertebral disks of the twy mouse at 3 weeks of age, and MGP gene expression was noted at the same time. These findings suggest that abnormal expression of MGP plays a major role in the pathologic calcification of the twy mouse.

Neural connection between the ventral portion of the lumbar intervertebral disc and the groin skin.

This study was designed to investigate neural mechanisms of referred pain in lumbar intervertebral disc lesions. Patients with a degenerative disc in lower lumbar segments occasionally complain of groin pain, which cannot be explained anatomically as having a radicular origin. In rats pretreated with intravenous application of Evans blue dye, the dye extravasation appeared in the groin skin after application of capsaicin to the ventral portion of the L5-6 intervertebral disc. This response occurred even in rats with a sectioned L-5 spinal nerve and sympathetic trunks, but did not occur in rats with a sectioned genitofemoral nerve. Capsaicin topically applied to the sciatic nerve did not cause dye extravasation in the hindpaw. Therefore, groin dye extravasation was not due to a direct effect of capsaicin but, rather, presumably was caused by an "antidromic axon reflex" of dichotomizing C fibers or to a segmental sympathetic reflex causing vascular permeability. The present results indicate that the ventral portion of the lumbar discs is neurally connected to the groin skin via the upper (L-2) lumbar spinal nerves in rats. Groin pain coincident with low-back pain may be explained as referred pain, indicating that a lesion is present in the ventral portion of the lumbar intervertebral disc space.

Hyperextension soft tissue injuries of the cervical spine--a review.

While a full understanding of continuing symptoms following a soft tissue hyperextension injury of the cervical spine remains elusive, recent research has shown that the explanation may lie with occult lesions beyond the musculoskeletal structures of the neck. The balance of the roles of injury, psychological factors, and the effects of litigation has shifted towards the former. However this injury would be unique if the latter two played only a minor role in determining recovery. It seems likely that among the large numbers of patients presenting with symptoms after hyperextension soft tissue injuries, a proportion will have occult bone, joint, or intervertebral disc lesions. Improvements in medical imaging techniques may allow better definition of these specific injuries and the development of more appropriate treatment. The search for a central nervous system lesion in humans continues and until this is demonstrated, many will dispute the existence of an organic brain syndrome. Evidence for significant injury to the temporomandibular joints, ear, and ophthalmic system has been found and this may be amenable to specialist intervention. While there is little evidence for effective treatments of the established injury, reduction in related disability appears most likely to be achieved by prevention. Improvements in automobile design, with particular reference to head restraints, could limit the cost to society of this common and disabling injury.

Spondylodiscitis in ankylosing spondylitis, inflammation or trauma? A description of six cases.

An uncommon, but well recognised complication of Ankylosing Spondylitis (AS) is spondylodiscitis, a destructive discovertebral lesion also called the Andersson lesion. We describe six cases, with variable clinical presentation and radiological appearance. Two had multiple lesions, in one patient spondylodiscitis was the presenting symptom of AS. None had a history of even a minor trauma. Prognosis was good with conservative treatment including NSAID's, rest, and physiotherapy. In two cases histopathology was studied and suggested sterile inflammation as the main etiologic factor. The literature is reviewed regarding the mechanisms that may contribute to these lesions: mainly inflammatory like increasing enthesopathy or mainly mechanical like pseudoarthrosis about a fracture site. It may be that both mechanisms can result in similar destructive intervertebral disc lesions.

Arthritis and ankylosis in twy mice with hereditary multiple osteochondral lesions: With special reference to calcium deposition

A murine autosomal recessive mutant named twy (tiptoe walking-Yoshimura) mouse showing multiple osteochondral lesions including ankylosis of the vertebral column and limb joints underwent sequential histopathological analysis of posterior limb joint lesions and intervertebral disc lesions. In the articular cartilage, a decrease in alcian blue-positive extracellular matrix and the presence of degenerated collagen fibers were found at the age of around 4-8 weeks. Calcium deposits in the articular cartilage were found at that time and later in the articular space and synovial tissue. Calcium deposits were also found in the intervertebral discs at 4 weeks. Using electron microscopy, some of the crystals were seen inside small vesicles. In both joints, degeneration of, and calcium deposition in, the articular cartilage progressed with age, finally producing bony ankylosis. These histological observations suggest that calcification and degeneration of the articular cartilage are the major factors in the pathogenesis of joint disorders in the twy mouse, and this mutant mouse provides a good model for studying the process and mechanism of osteoarthritic lesions, destructive arthritis and ankylosis.

Capsaicin applied to rat lumbar intervertebral disc causes extravasation in the groin skin: A possible mechanism of referred pain of the intervertebral disc

Administration of 10 μg of capsaicin into the anterior portion of a lumbar intervertebral disc of rats pretreated with Evans blue (i.v.) caused dye extravasation in the groin skin. This phenomenon occurred even when the spinal nerve of the same segment, bilateral sympathetic trunks, and/or the anterior L 2 spinal root had been cut; it did not occur in rats with a cut genitofemoral nerve. Infiltration of capsaicin solution directly into the genitofemoral nerve did not cause dye extravasation. These results suggested the presence of dichotomizing sensory C-fibers which innervate both the intervertebral discs and the groin skin in the L 2 spinal nerve. If such dichotomizing fibers exist in man, they may contribute to the groin pain sometimes associated with intervertebral disc lesions.