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Case series.This study compared the locations of arm pain, sensory symptoms, and subjective complaints of arm weakness in patients with cervical radiculopathy from MRI confirmed C6 and C7 nerve root compression.Cervical radiculopathy is defined as arm pain, sensory and motor symptoms caused by irritation of a cervical nerve root. The C6 and C7 roots are most commonly involved, and differentiating symptoms associated with each root has proven difficult. Cervical MRI allows accurate identification of nerve root compression and therefore makes it possible to explore symptom patterns that may differentiate C6 from C7 radiculopathy.A total of 122 patients with symptoms suggestive of cervical radiculopathy were recruited. Of these, 30 patients had MRI confirmed C6 and 39 patients C7 nerve root compression. By completing a study questionnaire, patients reported specific arm weakness, and marked the location of arm pain and tingling/numbness on graphic representations of the arm. Marked areas were interpreted by superimposing a grid that divided the arm into 54 distinct areas. The frequencies of reported symptoms with C6 and C7 were totaled and then compared with likelihood rations. Power analysis calculated that 27 patients would be needed in each group based on the assumption that a 30 percentage point difference in frequency of specific symptom would be clinically useful for differentiating C6 from C7 radiculopathy.Arm pain and sensory symptoms were diffuse, and were not distinctly different for C6 or C7 radiculopathy. Some weakness was reported by 41 percent of patients, with specific descriptions of weakness having limited value for differentiating between radiculopathies.The location of pain and sensory symptoms, and specific weakness complaints associated with symptomatic C6 and C7 nerve root compression overlap to the extent that caution should be exercised when predicting root involvement based on symptoms.3.

Study design Case report. Objective To present the second case of Brown-Sequard syndrome (BSS) produced by type III odontoid fracture managed by conservative treatment. Summary of background data The occurrence of BSS due to odontoid fracture is scarce. So far 6 cases have been reported, and only 1 is produced by type III odontoid fracture. The possible pathophysiology, clinical course and treatment outcome have been rarely discussed. Methods A 39-year-old man presented with weakness of his left arm and leg, mild neck pain, and impaired proprioceptive and light touch sensations below the left C2 dermatome. There were decreased pain and temperature sensations below the right C4 dermatome too. Computerized tomography showed odontoid type III fracture with posterior displacement at that level. Magnetic resonance imaging presented focal hyperintensity around the C2 vertebral level. High dose of prednisolone, close reduction with Gardner-Wells tong skull traction, following external stabilization by Halo-Vest and rehabilitation therapy were applied. Results Complete resolution of neck pain and significant improvement of motor and sensory functions, i.e., light touch and proprioception, were shown 2 months after spinal injury. Impaired temperature discrimination persisted, however. Conclusion BSS is rarely caused by type III odontoid fracture and this is the second report. Conservative intervention is advantageous for both type III odontoid fracture and BSS which is consistent with previous results.

STUDY DESIGN Case report. OBJECTIVE To present a case of primary hydatid cyst in the lumbar subcutaneous tissue affecting posterior paravertebral muscle and mimicking disc herniation. SUMMARY OF BACKGROUND DATA Cystic hydatid disease is a rare but significant parasitic disease in endemic areas. Musculoskeletal or soft tissue hydatidosis accounts for about 0.5% to 5% of all echinococcal infections in endemic areas and is almost secondary to the hepatic or pulmonary disease. Primary lumbar subcutaneous hydatid cyst affecting paravertebral muscle and extending to neural foramina is a very rare condition even in endemic areas. METHODS A 25-year-old-female patient was admitted with swelling and pain in the right lumbar region for 3 months. The pain was reflecting in the right gluteal region and the right leg. Lumbar extension and right lateral flexion was painful and straight leg raising test was positive at right side. There was a mild hypoesthesia at L5 dermatome. According to the magnetic resonance image that the clinician obtained for initial diagnosis of lumbar disc herniation, we found multi-cystic masses located at the right paravertebral muscle at the level of L3-L5 which extended to L4-L5 neural foramina and at subcutaneous tissue at the right gluteal region. RESULTS The patient was operated for the purpose of removal of cysts. Postoperatively, diagnosis of hydatid cyst was confirmed by histopathology. CONCLUSION By this case, we emphasize that cystic hydatid disease should be taken into consideration in the differential diagnosis of low back pain and could mimic disc herniation. LEVEL OF EVIDENCE N/A.

STUDY DESIGN: Spinal somatosensory-evoked potentials (SSEPs), elicited by mixed nerve and dermatomal stimulation, and compound evoked muscle potentials (CMAPs), elicited by lower thoracic interspinous space stimulation, were recorded in rats that underwent single nerve root transection. OBJECTIVES: To investigate and compare the effects of single nerve root transection using various electrophysiological models and to define a monitoring strategy that can easily and accurately predict compromise caused by a single lumbosacral nerve root injury. SUMMARY OF BACKGROUND DATA: Neuromonitoring is an important and effective preventive measure against neurologic complications during spinal surgery, but monitoring the lumbosacral nerve roots is not well established. METHODS: Rats received (Group I) a sham operation or had the (Group II) left L4, (Group III) L5, or (Group IV) L6 nerve root transected. SSEP were recorded at the thoracolumbar junction following stimulation of the sciatic nerve (M-SSEP) and the L5 dermatome (D-SSEP). CMAP was recorded at the intrinsic muscles of the foot by electrical stimulation in the lower thoracic spinal cord. Potentials recorded before and after a single nerve root transection were compared and correlated with clinical status by walking-track analysis 1 week later. RESULTS: Relative amplitudes in Group II were 54.1% (M-SSEP), 84.6% (D-SSEP), and 85.5% (CMAP); 25.2% (M-SSEP), 66.5% (D-SSEP), and 85.8% (CMAP) in Group III; and 66.5% (M-SSEP), 95.5% (D-SSEP), and 23.2% (CMAP) in Group IV. M-SSEP is sensitive but not specific to single nerve root injury. D-SSEP and CMAP are less sensitive but more specific. CONCLUSIONS: Injury to a single lumbosacral nerve root is diagnosed more easily with M-SSEP. With D-SSEP and CMAP, it was possible to differentiate the lesioned nerve root by stimulating the primary dermatome or recording from the innervated muscle. M-SSEP is an easy-sampling and appropriate tool for screening nerve root injury; its poor specificity may be overcome by using D-SSEP and CMAP in addition. Optimal monitoring of the lumbosacral nerve roots during lumbar spinal surgery requires the administration of M-SSEP, D-SSEP, and CMAP to provide independent verification of lumbosacral nerve root integrity and to allow detection of the occasional injuries that selectively affect either the sensory or motor system.

STUDY DESIGN Spinal somatosensory-evoked potential (interspinous-space-recorded evoked potentials after peripheral nerve or dermatomal stimulation) and conductive spinal cord evoked potential (interspinous-space-recorded evoked potentials after spinal cord stimulation) were analyzed in rats under different concentrations of the anesthetic desflurane. OBJECTIVES To investigate and compare the effects of a new volatile anesthetic, desflurane, on the common intraoperative neuromonitoring models. SUMMARY OF BACKGROUND DATA Intraoperative evoked potentials are sensitive to most anesthetics. Interpretation of the data becomes complicated because of a suppression effect caused by the anesthesia. Desflurane has become a valuable anesthetic in neurosurgery because of its pharmacokinetic advantages. METHODS Fifteen rats were placed under general anesthesia, and vital signs were closely monitored. Needle recording electrodes were placed stereotactically into the thoracolumbar interspinous ligament; dermatomal somatosensory-evoked potential by L5 dermatome, mixed-nerve somatosensory-evoked potential by sciatic nerve stimulation, and spinal cord evoked potential of the same recording electrodes elicited by C2-C3 interspinous stimulation were obtained. The effects of desflurane were examined at end-tidal concentrations of 6% (1.05 minimal alveolar concentration), 9% (1.57 minimal alveolar concentration), and 12% (2.10 minimal alveolar concentration). RESULTS Amplitude decreased and latency was delayed in all three kinds of potentials, and the more so with higher concentrations. Comparing 9% with 6% desflurane, the amplitude in dermatomal somatosensory-evoked potential, mixed-nerve somatosensory-evoked potential, and spinal cord evoked potential decreased to 84.3%, 88.9%, and 70.8%, respectively, values with no statistically significant difference. However, at 12%, again compared with 6%, the amplitude decreased further to 64.4%, 70.3%, 41.8%, respectively; mixed-nerve somatosensory-evoked potential and dermatomal somatosensory-evoked potential were significantly more preserved than spinal cord evoked potential (P = 0.04). CONCLUSIONS The concentration of desflurane alters the amplitude of somatosensory-evoked potential and spinal cord evoked potential, and, to a lesser degree, delays the latency; spinal cord evoked potential is more liable to be suppressed than somatosensory-evoked potential. The dose-dependent suppression effect on amplitude should be considered when interpreting changes during surgery. Furthermore, the potential benefit of somatosensory-evoked potential elicited by direct major nerve stimulation should be considered because of its large amplitude and higher resistance, even with a greater concentration of volatile anesthetics.

Study Design. Neurotracer was applied to various sites in the rat lumbar spine and related tissues. The segmental distribution of labeled neurons in dorsal root ganglia (DRG) was investigated. Objectives. To clarify the stereoscopic structure of afferent fibers innervating the lumbar spine and related tissues. Summary of Background Data. Afferent fibers in the rat L5–L6 lumbar intervertebral disc are reported to originate from neurons in L1 and L2 DRG. However, anatomic studies determined that each dorsal ramus of the spinal nerve sends nerves to dorsal elements of the corresponding lumbar vertebra. Methods. Fluorescent neurotracer DiI (1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate) was applied to various sites of the lumbar spine and related tissues in the L2, L5, and L6 levels in rats. DRG were sectioned 3 weeks after DiI application. Rostrocaudal distribution of DiI-labeled neurons was investigated. Results. At L5, DiI-labeled neurons were prominent in DRG L3 for the lamina, L2 for the spinous process, L2 for the back muscle fascia, and L1 for the skin. Dorsal elements are therefore innervated by neurons in more rostral DRG. In the transverse plane, the more distant from the DRG a site was, the more rostral the DRG innervating the site. This structure suggested a concentric innervation pattern in the transverse plane. Conclusion. Stereoscopically, the peripheral innervation territory of a lumbar DRG is conical, with the apex at the ganglion and the base circumference located on the dermatome. The lumbar spine itself is involved in the conical innervation territories of DRG.

Study Design. Peripheral sensory functions in patients with radiculopathy resulting from lumbar disc herniation and in control individuals were analyzed using current perception threshold testing. Objective. To evaluate the severity of sensory disturbance quantitatively in patients with lumbar radiculopathy. Summary of Background Data. Subjective evaluation of the severity of sensory disturbance associated with spinal disorders using conventional methods often is difficult. Current perception threshold evaluation is a recently proposed method for studying peripheral nerve dysfunction. This is a quantitative sensory test for analyzing functions of A-beta, A-delta, and C fibers. Methods. In this study, 48 patients with lumbar radiculopathy resulting from lumbar disc herniation were examined. The mean age of the patients was 37.9 years. All the patients had pain distribution from the compression of one lumbar nerve root (L5 or S1), and unequivocal unilateral disc herniation of the corresponding level was shown by magnetic resonance imaging. Eleven healthy volunteers were used as control subjects. Their mean age was 38.2 years. Current perception threshold evaluation using a Neurometer device was performed at three frequencies: 2000, 250, and 5 Hz. The stimulus sites were located on the dorsal side of the first metatarsus (the L5 dermatome) and the dorsal side of the fifth metatarsus (the S1 dermatome). These sites were investigated on both legs in all the patients and control subjects. The intensity of pain was scored using a visual analog scale. Results. In the control group, there were no significant differences in current perception threshold values at any frequency between the left and right legs. In the patient group, the current perception threshold values in the affected legs were significantly higher than those in the contralateral legs at all frequencies. The current perception threshold values in the affected legs in the patient group were significantly higher than those in the control subjects at 2000 and 250 Hz, whereas there were no significant differences at 5 Hz. The current perception threshold values in the affected legs were significantly higher in patients with hypesthesia than in those without hypesthesia at 2000 and 250 Hz, and in patients with severe pain than in those with less pain at 5 Hz. Conclusions. Current perception threshold testing showed that the functions of A-beta, A-delta, and C fibers deteriorated in patients with lumbar radiculopathy. This technique may be useful for quantifying sensory nerve dysfunction in patients with radiculopathy.

STUDY DESIGN Dorsal root ganglion (DRG) neurons that have dichotomizing axons to the lumbar facet joint and to the sciatic nerve were investigated in rats using a double fluorescent labeling technique. OBJECTIVES To clarify the existence of DRG neurons with dichotomizing axons projecting to the lumbar facet joint and to the sciatic nerve in rats. SUMMARY OF BACKGROUND DATA DRG neurons having dichotomizing axons have been reported in several species and are considered to be related to referred pain. However, such DRG neurons have not been investigated in the lumbar spine. Clinically, pain from the lumbar facet joint is sometimes referred to the lower extremities innervated by the sciatic nerve. METHODS Two kinds of neurotracers (DiI and FG) were used in the present double-labeling study. DiI crystals were placed in the left L5-L6 facet joint, and FG was applied to the ipsilateral sciatic nerve or along the midline of the L5 dermatome. Bilateral DRGs T13-S1 were observed by fluorescence microscope. RESULTS DRG neurons double labeled with DiI and FG were recognized only in the ipsilateral DRGs from L3 to L6 levels. Approximately 3% of DRG neurons innervating the L5-L6 facet joint had other axons to the sciatic nerve. By contrast, no double-labeled neurons were observed after FG was applied to the L5 dermatome. CONCLUSIONS In rats approximately 3% of DRG neurons innervating the lumbar facet joints have dichotomized axons projecting to the sciatic nerve.

Study Design. The function of sensory nerve fibers in patients with lumbar radiculopathy and in control individuals was evaluated using quantitative sensory testing. Objectives. To investigate the effect of lumbar nerve root compression on different populations of nerve fibers and to explore the function of sensory nerve fibers in neighboring nerve roots not involved in the mechanical compression. Background Data. Results from experimental and clinical studies indicate that chronic compression of lumbar nerve roots affects the large myelinated nerve fibers. The majority of nerve fibers involved in the sensation of pain, however, are small afferent nerve fibers. It is therefore of interest to study the effect of compression on large and small sensory afferent channels. Several authors have elucidated the biochemical interaction between disc tissue and nerve roots. Chemical substances in the epidural space can reach the nerve fibers in nerve roots at the same or neighboring lumbar segments. In this way, fibers not involved in the mechanical compression may be affected. Methods. The small nerve fibers were studied using tests for thermal thresholds (thermotest), and the large myelinated fibers were studied by vibrametry. Forty-two patients were investigated in the symptomatic and the asymptomatic leg, and the results were compared with those of 21 healthy individuals. Results. The thresholds of cold, warmth, and vibration were significantly increased in the dermatome of the compressed nerve root, indicating that large and small sensory nerve fibers were affected. Further, the thresholds were significantly increased in the neighboring dermatomes in the symptomatic and the asymptomatic leg. Conclusion. Large and small sensory afferent nerve fibers are affected in lumbar radiculopathy. The increase in sensation thresholds in the ipsilateral neighboring dermatome and in the dermatomes in the asymptomatic leg indicates that adjacent nerve roots are involved in the pathophysiology of sciatica in patients with lumbar disc herniation.

Study Design. Thirty-three patients with single-level, unilateral lumbosacral radiculopathy underwent microdecompression and intraoperative dermatomal evoked potential monitoring. Side-to-side latency asymmetry was calculated. A criteria for "abnormal" was defined. Intraoperative dermatomal evoked potentials were obtained before and after decompression. The changes were correlated with clinical outcome at the 3-month follow-up examination. Objectives. To determine whether intraoperative dermatomal evoked potential latency asymmetry confirms nerve root compression and whether an improvement of latency asymmetry after decompression predicts a good clinical outcome. Summary of Background Data. Intraoperative dermatomal evoked potential has been proposed as a test to assess the adequacy of nerve root decompression. Initial reports suggested improvement of dermatomal evoked potential amplitude and latency after decompression. The clinical efficacy is controversial because of its technical difficulty and inherent variation. Methods. Cervical recording was chosen to reduce the effects of anesthesia. The asymptomatic nerve root was used as a control. Quality of the tracings was determined by evoked potentials-to-noise amplitude ratio. Clinical outcome was based on patient's pain relief and satisfaction. Results. Tracings of acceptable quality were obtained at baseline in 57.6% (19 of 33) of patients. A side-to-side latency asymmetry > 5% was defined as abnormal. Before decompression, 68.4% (13 of 19) of patients had an abnormal dermatomal evoked potential. After decompression, latency asymmetry returned to normal in every patient. Clinical outcome was good or excellent in 13 patients, fair in four patients, and poor in two patients. Dermatomal evoked potential latency improvements were not related to variation in clinical outcome. Conclusions. Intraoperative dermatomal evoked potential monitoring is technically demanding. Finding reproducible potentials is difficult. More research is necessary before general use of dermatomal evoked potentials for monitoring nerve root decompression.

Study design Observational case series. Objective To compare the pattern of distribution of radicular pain with published dermatome charts. Summary of background data Dermatomal charts vary and previous studies have demonstrated significant individual subject variation. Methods Patients with radiologically and surgically proven nerve root compression (NRC) caused by prolapsed intervertebral disc completed computerized diagrams of the distribution of pain and pins and needles. Ninety-eight patients had L5 compressions and 83 had S1 compressions. Results The distribution of pain and pins and needles did not correspond well with dermatomal patterns. Of those patients with L5 NRC, only 22 (22.4%) recorded any hits on the L5 dermatome on the front, and only 60 (61.2%) on the back with only 13 (13.3%) on both. Only 1 (1.0%) patient placed more than 50% of their hits within the L5 dermatome. Of those patients with S1 NRC, only 3 (3.6%) recorded any hits on the S1 dermatome on the front, and only 64 (77.1%) on the back with only 15 (18.1%) on both. No patients placed more than 50% of their hits within the S1 dermatome. Regarding pins and needles, 27 (29.7%) patients with L5 NRC recorded hits on the front alone, 27 (29.7%) on the back alone, and 14 (15.4%) on both. Nineteen (20.9%) recorded more than 50% of hits within the L5 dermatome. Three (3.6%) patients with S1 NRC recorded hits on the front alone, 44 (53.0%) on the back alone, and 18 (21.7%) on both. Twelve (14.5%) recorded more than 50% of hits within the S1 dermatome. Conclusion Patient report is an unreliable method of identifying the anatomical source of pain or paresthesia caused by nerve root compression. Level of evidence 4.

Study design The level of dorsal root ganglia that receives sensory afferent nerves from the anterior portion of the lower lumbar intervertebral disc was investigated in rats using a retrograde transport method. Objectives Sometimes patients with lower lumbar disc lesions complain of inguinal pain that does not correspond to the dermatome of the injured nerve roots. To investigate the origin of the pain, the authors studied the sensory innervation to the anterior portion of the lumbar intervertebral disc. Summary of background data The innervation to the posterior portion of the lumbar disc has been extensively investigated and has been reported to be segmental. However, little is known about the nerve supply to the anterior portion of the lumbar disc. Methods The retrograde transport method was used in rats. As tracers, horseradish peroxidase and choleratoxin B subunit were used. Horseradish peroxidase crystals were placed on the anterior portion of the L5-L6 disc, and choleratoxin B subunit was injected into the L5-L6 disc. The bilateral dorsal root ganglia were histologically examined. Results Labeling of L1 and L2 dorsal root ganglia neurons was recognized. No neurons were labeled in dorsal root ganglia of other levels, including the segmentally corresponding L5. Conclusions Using the retrograde transport method, the authors demonstrated that the anterior portion of the L5-L6 lumbar intervertebral disc was innervated from L1 or L2 spinal nerves in rats. These results appear to explain the reason why patients with lower lumbar disc lesions sometimes complain of inguinal pain corresponding to the L1-L2 dermatome.

Study design: Prospective study of 212 patients with groin pain but without low back pain. Objective: To evaluate discogenic groin pain without low back pain or radicular pain. Summary of background data: Patients feel low back pain originating from discogenic disease. It has been reported that the rat lower lumbar discs are innervated mainly by L2 dorsal root ganglion neurons. Thus, it is possible that patients feel referred groin pain corresponding to the L2 dermatome originating from intervertebral discs; however, the referred pain has not been fully clarified in humans. Methods: We selected 5 patients with groin pain alone for investigation. The patients suffered from groin pain and showed disc degeneration only at 1 level (L4-L5 or L5-S1) on magnetic resonance imaging. Patients did not show any hip joint abnormality on radiography or magnetic resonance imaging. To prove that their groin pain originated in degenerated intervertebral discs, we evaluated changes in groin pain after infiltration of lidocaine into hip joints and examined pain provocation on discography, pain relief by anesthetic discoblock, and finally anterior lumbar interbody fusion surgery. Results: All patients were negative for hip joint block, positive for pain provocation on discography, and positive for pain relief by anesthetic discoblock. Furthermore, bony union was achieved 1 year after anterior interbody fusion surgery in all patients, and visual analogue scale score of groin pain was significantly improved at 1 year after surgery in all patients (P < 0.05). Conclusion: In the current study, we diagnosed discogenic groin pain, using magnetic resonance imaging, infiltration of lidocaine into the hip joint, pain provocation on discography, pain relief by anesthetic discoblock, and lumbar surgery. It is important to consider the existence of discogenic groin pain if patients do not show low back pain.

Regions of sensory impairment of 71 patients in 86 lumbar spinal nerve blocks (L4 19 cases, L5 41 cases, S1 26 cases) were determined by the writing brush method. Distinctive regions included the medial side of the lower leg, the side of the first dorsal digit, and the side of the fifth digit respectively of the L4 (88%), L5 (82%) and S1 (83%) spinal nerves without 100% matching because of displacement of one spinal segment by the furcal nerve. A band-like impaired zone from the proximal to the periphery appeared in 42%, 44%, and 92%, respectively, of the L4, L5, and S1 blocks. The marked difference between L4, L5, and S1 may be caused by the diversity of the dorsal rami of the spinal nerves and double control by the lateral cutaneous nerve of the thigh.

Regions of sensory impairment of 71 patients in 86 lumbar spinal nerve blacks (L4 19 cases, L5 41 cases, S1 26 cases) were determined by the writing brush method, Distinctive regions included the medial side of the lower leg, the side of the first dorsal digit, and the side of the fifth digit respectively of the L4 (88%), L5 (82%) and S1 (83%) spinal nerves without 100% matching because of displacement of one spinal segment by the furcal nerve. A band-like impaired zone from the proximal to the periphery appeared in 42%, 44% and 92%, respectively, of the L4, L5, and S1 blocks. The marked difference between L4, L5, and S1 may be caused by the diversity of the dorsal rami of the spinal nerves and double control by the lateral cutaneous nerve of the thigh., 名古屋大学博士学位論文 学位の種類 : 博士(医学)(論文) 学位授与年月日:平成4年7月20日 新田弘幸氏の博士論文として提出された

Somatosensory evoked potentials (SEPs) were recorded at the lumbar spine following stimulation of the tibial nerve (mixed-nerve SEP; MSEP), the sural nerve (specific nerve SEP; SSEP), and the skin corresponding to the L6 and S1 dermatomes (dermatomal field SEP; DSEP-L and DSEP-S) in the hog. To determine the sensitivity of these three SEPs to the single nerve root (S1 root) function, the effects of nerve roots lesioning were investigated. Cutting S1 nerve root reduced the peak-to-peak amplitude of MSEP by only 28% in comparison with baseline values. The relative amplitudes of SSEP, DSEP-L, and DSEP-S were decreased by 46%, 11% and 51%, respectively. When S1 nerve root was left intact and L5, L6, and S2 nerve roots were cut, the relative amplitudes of MSEP, SSEP, DSEP-L, and DSEP-S were decreased to 68%, 73%, 31%, and 74%, respectively. These results indicate that DSEP-S is as sensitive to the function of S1 nerve root as SSEP but the sensitivities of DSEP-S and SSEP are low in the hog. MSEP is shown unsuitable to monitor the single nerve root dysfunction.

STUDY DESIGN Case description. OBJECTIVE To clinically and radiographically describe a traumatic spinal epidural hematoma (TSEH) without adjacent spinal column fracture or soft tissue injury that completely resolved, without surgical intervention. SUMMARY OF BACKGROUND DATA Symptomatic TSEH is an infrequent condition after spinal trauma, accounting for 0.5% to 1.7% of cases. It can result in permanent neurologic deficits if not treated in a timely and appropriate manner. METHODS A 50-year-old man presented with progressive lower motor weakness and sensory change at 2 days after blunt trauma to the upper back area. Neurologic examination revealed paraplegia and hypesthesia below the T4 sensory dermatome. Magnetic resonance imaging for cervicothoracic spine showed a space-occupying lesion in the dorsal spinal epidural space from C7 to T5. The lesion was consistent with acute stage hematoma of the spinal epidural space. RESULTS The patient was prepared for decompression surgery. However, the patient's neurologic symptoms began to improve (grade 4/5) at 2 hours after onset of paraplegia. Surgical intervention was delayed, and the patient was treated conservatively with close neurologic monitoring. Three days after onset of symptoms, the patient's neurologic symptoms recovered completely. The follow-up magnetic resonance imaging at 12 days after the event showed complete resolution of the epidural hematoma. CONCLUSION An unpredictable extensive epidural hematoma can occur after blunt trauma of the cervicothoracic spine in patients at low risk for hemorrhage. This case illustrates that immediate surgical intervention may not always be necessary in certain patients with TSEH. Conservative management with careful observation may play a role as a management option for patients initially presenting with severe neurologic dysfunction if neurologic recovery is early and sustained.

The relationship between clinical status and preoperative and intraoperative dermatomal somatosensory-evoked potentials was investigated as a function of test site. Results indicated that the specificity and sensitivity of dermatomal somatosensory-evoked potentials varied with level of involvement: L5 demonstrated greatest agreement with equal correlation at L3, L4, and S1. Variables that influenced correlation included history of previous surgeries, type of anesthetic used, interpretation criteria, and whether the patient was awake or asleep. It was concluded that dermatomal somatosensory-evoked potentials can provide the surgeon with diagnostic and intraoperative information regarding the functional integrity of single nerve root function.

STUDY DESIGN: Case report. OBJECTIVES: A rare case of anterior cervical second root traumatic neuroma with no history of trauma is reported, and possible etiology is discussed. SUMMARY OF BACKGROUND DATA: Traumatic neuroma is the reactive, nonneoplastic proliferation in the injured nerve. Several atypical locations of traumatic neuroma have been reported. To date, only 4 cervical traumatic neuroma cases with no history of trauma have been reported, and, to our knowledge, there is no case of bilateral cervical traumatic neuroma published in the literature. METHODS: A patient with a history of neck and left upper extremity pain, who had hypoesthesia in left C2 dermatome on neurologic examination is presented. A left C2-C3 hemilaminectomy and tumor extirpation were performed. RESULTS: A histopathologic study revealed features of a typical traumatic neuroma. The patient had no deficits on her postoperative neurologic examination, and her neck and left arm pain improved. The unusual location of this lesion and possible etiology of such a traumatic neuroma are discussed. CONCLUSIONS: A rare case of anterior bilateral cervical second root traumatic neuroma with no history of trauma is reported. An unnoticed history of trauma may play an etiologic role in the development of these lesions.

Study Design. The case report of a 38-year-old man with a unique acute, triple-level, noncontiguous thoracic disc herniation (T6, T9–T10, and T11–T12), delayed onset of lower limb weakness, paresthesias below the T10 dermatome, and urinary dysfunction following minor trauma resulting from a motorcycle accident. Objectives. To present an unusual case of herniation that could involve ambiguous test results (imaging findings not necessarily correlated with severity of clinical manifestations). Summary of Background Data. Multiple-level symptomatic disc herniations of the thoracic spine are rare, and the reported cases are mostly of contiguous, two-level lesions with chronic clinical presentation. No case of acute three-level noncontiguous ruptured thoracic disc herniations with myelopathy has been reported. Methods. Through the left transthoracic approach, partial corpectomy, complete discectomy, and interbody fusion of the T9–T10 vertebrae were performed. The less prominent lesions of the T6 and T12–L1 vertebrae were left untreated. Results. Remarkable improvement of neurologic symptoms, including motor weakness and bladder dysfunction, was observed 1 week after operation. At 1-year follow-up, he could walk without aid and with a somewhat spastic gait. However, paresthesias below dermatome T12 persisted. The patient refused to accept the recommendation of further surgical decompression of the nerves at the T6 and T12–L1 vertebral lesions. Conclusion. Since the presentation of thoracic disc herniation is variable and difficult to correlate with imaging findings, decompression at all lesion levels in a patient with symptomatic multiple-level ruptured thoracic disc herniations may be necessary to achieve complete symptom relief and satisfactory results.

STUDY DESIGN This prospective study consisted of mechanical stimulation of cervical nerve roots C4 to C8 in patients with cervical radicular symptoms undergoing diagnostic selective nerve root block. OBJECTIVES To document the distribution of pain and paresthesias that result from stimulation of specific cervical nerve roots and compare that distribution to documented sensory dermatomal maps. SUMMARY OF BACKGROUND DATA Cervical dermatomes were first studied in the late 19th century. The results of those studies underpin current clinical decision making for patients with neck and arm pain. However, it has been observed that patients with radicular symptoms may have cervical pathology by radiographic imaging that is not corroborative, or have imaging studies that suggest a lesion at a level other than the one suggested by the patient's dermatomal symptoms. These observations may suggest that cervical dermatomal mapping is inaccurate or the distribution of referred symptoms (dynatome) from cervical root irritation is different than the sensory deficit outlined by dermatomal maps. METHODS Inclusion criteria consisted of consecutive patients undergoing fluoroscopically guided diagnostic cervical selective nerve root blocks from C4 to C8. Immediately preceding contrast injection, mechanical stimulation of the root was performed. An independent observer interviewed and recorded the location of provoked symptoms on a pain diagram. Visual data was subsequently compiled using a 793 body sector bit map. Forty-three clinically relevant body regions were defined on this bit map. Frequencies of symptom provocation and likelihood of symptom location from C4 to C8 stimulation of each nerve root were generated. RESULTS One hundred thirty-four cervical nerve root stimulations were performed on 87 subjects. There were 4 nerve root stimulations at C4, 14 at C5, 43 at C6, 52 at C7, and 21 at C8. Analyzing the frequency of involvement of the predetermined clinically relevant body regions either individually or in various combinations yielded more than 1,000 bits of data. Although the distribution of symptom provocation resembled the classic dermatomal maps for cervical nerve roots, symptoms were frequently provoked outside of the distribution of classic dermatomal maps. CONCLUSION The current study demonstrates a distinct difference between dynatomal and dermatomal maps.

Twenty patients with a radicular syndrome, who underwent surgery for unilevel lumbosacral disc herniations verified by computed tomography were investigated with neurophysiologic tests (electromyograms, F-responses, dermatome somatosensory evoked potentials) preoperatively and 1 year postoperatively. At least one test revealed a pathologic abnormality preoperatively in 13 patients, but in 5 patients only the nerve root level corresponded to computed tomographic findings. Discordance between neurophysiologic and radiologic findings did not predict a surgical success rate. if all neurophysiologic tests were normal the outcome was significantly worse than if any of the tests showed an abnormality (P < 0.01). Four patients who were improved after surgery still had abnormal neurophysiologic findings. In conclusion, neurophysiology is not useful to diagnose the exact level of a nerve root lesion, but may reveal whether it is present. Electrodiagnosis is recommended if radiology and clinical testing conflict. If positive, it may then serve to justify surgical exploration.

This study examined the ability of somatosensory-evoked and dermatomal-evoked potentials to predict motor return after acute spinal cord injury. Fifty-seven of 102 patients who were studied with somatosensory-evoked potentials and dermatomal-evoked potentials were followed for more than 1 year, and their initial electrophysiologic studies were correlated with motor improvement. No patient with a complete spinal cord injury on initial physical evaluation ever developed motor return. An initial examination demonstrating incomplete spinal cord injury heralded a result of walking or better in 56.4% of incomplete patients with spinal cord injury. Both the initial physical examination and evoked potentials were reasonable predictors of further motor improvement. However, evoked potentials added little or no useful prognostic information to the initial physical examination in either complete or incomplete spinal cord injury patient groups.

Dermatomal evoked potentials are being used to obtain accurate information concerning the viability of specific nerve root pathways and the quality and extent of nerve root decompression. Twelve patients with quantifiable weakness were selected and tested before, during, and after surgery. Nine patients showed dramatic intraoperative electrical improvement, including decreased latencies and/or increased amplitudes; all had postoperative relief of pain and motor return. Three patients showed variable intraoperative electrical responses with complete pain relief but no motor improvement. No patients had false-negative findings. Intraoperative monitoring of dermatomal evoked potentials appears to be of value in predicting the quality of spinal decompression. Similar monitoring of somatosensory evoked potentials alone cannot provide the specificity for individual root levels that is available by monitoring individual dermatomes.

This report concerns the use of dermatomal somatosensory-evoked potentials (DSEPs) for intraoperative monitoring in the surgical management of a group of patients with lumbar spinal stenosis. Thirty patients with lumbar spinal stenosis underwent preoperative evaluation by DSEPs by use of electrical stimulation of the skin corresponding to the L4, L5, and S1 dermatomes. The specific dermatome to be monitored intraoperatively was selected by correlating those data with physical and radiographic findings and, in certain cases, the results of selective nerve root blocks. Intraoperative baseline (predecompression) DSEP values were obtained after positioning the patient on the operative frame. Monitoring was performed during surgery and post-decompression values were obtained after neural decompression. For six cases of unilateral nerve root decompression, an average 9-msec decrease in latency was noted on the operated side and a 3-msec decrease on the nonoperated side. For 24 cases of bilateral decompression, an average 8-9-msec decrease in latency was noted bilaterally. This method has been found helpful in assessing the adequacy of neural decompression intraoperatively.

Correct dermatome identification is essential to reduce nomenclature and surgical errors, to improve neurologic correlation, and to produce accurate statistics regarding low-back problems. The phylogenetic category of the spine must be known and junctional transitional vertebrae within the column properly identified and localized. This article emphasizes the appearances of, and the different positions of, transitional vertebrae at the thoracolumbar and lumbosacral junctions in the vertebral sequence depending on the phylogenetic category of the patient. It describes three additional characteristics of these anomalous vertebrae. Suggestions are made to eliminate the confusion and mistakes produced by the presence of these frequent variants.

The purpose of this study is to establish the correct diagnosis of the location and extent of intraspinal cord lesions in cases of continuous or mixed-type ossification of the posterior longitudinal ligament and to estimate the postoperative prognosis using evoked spinal cord potentials (ESCP). Twenty-six patients, who underwent surgery from 1985 to 1987 and who have been followed for more than 6 months, were examined using a conductive ESCP, which demonstrates lower extremity, bowel, and bladder function, and a segmental ESCP and dermatome segmental ESCP, which demonstrate upper extremity function. A five-pole recording electrode was placed in the cervical epidural space. The stimulation sites were the thoracic epidural space for conductive ESCP, the median nerve at the elbow for the segmental ESCP, and the finger surface for the dermatome segmental ESCP. In cases in which the ESCP disappeared at the middle of the narrow cervical spinal canal, another stimulating electrode was placed in the cisterna magna, and a descending conductive ESCP was recorded to monitor the upper border of the spinal lesion. New findings, which could not be observed by roentgenograms, myelography, and CT scan, were detectable using this technique.

Sacral dermatomal-evoked responses (DEP) and posterior tibial nerve (PTN) somatosensory-evoked potentials (SSEP) were recorded 28 hours after gunshot injury to the 12th thoracic vertebra of a 17-year-old male. Repeatable responses were obtained from stimulation of the fourth sacral dermatome despite absence of repeatable PTN responses. This suggestion of "sacral sparing" was accompanied by clinical improvement of neural function during the hospital course and 10 months after discharge. This case suggests DEP can make valuable contributions in the diagnosis of sacral sparing in acute spinal cord injury. Considerations regarding the unusual ipsilateral scalp recording location for sacral DEP are discussed.