Level Of Cord Compression Research Articles

Differential recording of upper and lower cervical N13 responses and their contribution to scalp recorded responses in median nerve somatosensory evoked potentials

To distinguish the different origins of cervical N13 potentials in median nerve somatosensory evoked potentials (SSEPs), cervical N13 potentials were recorded by two different montages. The abnormal patterns of the SSEPs were compared to the abnormal evoked spinal cord responses (ESCPs) recorded from posterior epidural space in 13 patients with various cervical lesions. SSEPs from the posterior cervical surface were recorded from the mid-cervical level with anterior neck reference (Cv5-AN) and from the upper cervical level with inion reference (Cv2-IN). Scalp responses were recorded from the parietal region contralateral to the stimulating side with non-cephalic reference (shoulder contralateral to stimulating side). ESCPs were recorded from the posterior epidural space using catheter electrodes or needle electrodes inserted into the ligamentum flavum. Lower cervical N13 (LC-N13) recorded from the Cv5-AN montage showed similar latency to upper cervical N13 (UC-N13) recorded from the Cv2-IN montage. The latency of the early part of the P13–P14 complex in the scalp montage was similar to that of the UC-N13 and the negative peak latency of the ESCPs recorded at the C2–3 level. Attenuation of the LC-N13 and relatively preserved UC-N13 and P13–P14 were characteristic in patients with cervical syringomyelia and compression cervical myelopathy at the mid-cervical levels. Attenuation of the UC-N13 with normal LC-N13 was characteristic in patients with cervical spondylotic myelopathy who showed conduction blockade of the ESCPs at the C3–4 level. In a patient with schwannoma at the C1–2 level, conduction blockade of the ESCPs was observed at the C1–2 level. P13 was normal but P14 was prolonged. UC-N13 and P13 latencies were similar to the negative peak latency of the ESCPs at the C2–3 level. We demonstrated that two different cervical N13 potentials can be recorded by two different montages and they represent different behavior in various spinal cord lesions. In addition, at least the early part of the P13–P14 complex originates in the upper cervical region. To distinguish two different cervical N13, it is useful to detect not only the cervical pathology but also the symptomatic cervical cord compression level in patients with cervical myelopathy.

Cervical laminectomy without fusion in patients with rheumatoid arthritis.

The authors performed a prospective study to determine whether cervical laminectomy without simultaneous fusion results in spinal instability. Because of clinical and radiographic signs of cord compression, 15 patients with rheumatoid arthritis (including one with Bechterew's disease) and severe involvement of the cervical spine underwent decompressive laminectomy without fusion performed on one or more levels. Preoperative flexion-extension radiographs demonstrated dislocation but no signs of instability at the level of cord compression. Clinical and radiological reexamination were performed twice at a median of 15 months (6-24 months) and 43 months (28-72 months) postoperatively. One patient developed severe vertical translocation 28 months after undergoing a C-1 laminectomy, which led to sudden tetraplegia. She required reoperation in which posterior fusion was performed. No signs of additional instability at the operated levels were found in the remaining 14 patients. In three patients increased but stable dislocation was demonstrated. The results of clinical examination were favorable in most patients, with improvement of neurological symptoms and less pain. The authors conclude that decompressive laminectomy in which the facet joints are preserved can be performed in the rheumatoid arthritis-affected cervical spine in selected patients in whom signs of cord compression are demonstrated, but in whom radiographic and preoperative signs of instability are not. Performing a simultaneous fusion procedure does not always appear necessary. Vertical translocation must be detected early, and if present, a C-1 laminectomy should be followed by occipitocervical fusion.

頚椎後縦靭帯骨化症における術前後のＭＲＩの検討

We evaluated the clinical status and MRI findings of patients with cervical myelopathy due to OPLL before and after surgery. This study consisted of 25 cases (male 15, female 10) who received cervical laminoplasty. The transverse area of the spinal cord at the maximum cord compression level was measured and we compared the transverse area with surgical outcome. The clinical results were evaluated according to the Japanese Orthpaedic Association (JOA) score. Recovery after surgery was evaluated using the formula suggested by Hirabayashi et al. There were no statistically significant differences between the increase of the transverse area and surgical outcome. Patients who showed intramedullary signal intensity in the T2 weighted MR image at the maximum cord compression level pre-and postoperatively had poor recovery of neurological symptoms.

Characteristics of spinal cord compression in adenocarcinoma of prostate

Of 611 patients with biopsy-proved adenocarcinoma of the prostate, spinal cord compression developed in 41 (6.7%) at a median interval of twenty-four months after primary diagnosis. Spinal cord involvement most often occurred in the thoracic area, with 95 per cent of patients showing radiographic evidence of osseous vertebral metastasis at the level of cord compression. All lesions but one were located extradurally, and patients with Stage D2 disease, by virtue of bony metastases, were therefore at greatest risk for development of neurologically compressive disease. There was also a significant increase in the incidence of spinal cord involvement among the more poorly differentiated tumors, although tumor histology did not appear to influence the median interval between vertebral metastasis and cord compromise. Survival following spinal cord involvement was relatively poor and unrelated to tumor differentiation. Forty-six per cent of patients survived less than six months and 20 per cent less than two months. The two most noteworthy survivors are alive at thirty and ninety-seven months, the latter after combined treatment for an intradural lesion.

Spinal cord contusion injury: experimental dissociation of hemorrhagic necrosis and subacute loss of axonal conduction.

Previously reported experimental models for spinal cord contusion injury do not allow the independent control of compression and contact velocity required for interpretation of experimental data relating kinematics of vertebral injury to spinal cord injury. Therefore, controlled dynamic compression of the spinal cord was used to study compression and contact velocity as independent variables. Cord conduction was assessed using the latency of somatosensory evoked potentials in response to hindlimb stimulation. The latency increase at 4 hours after contusion differed significantly between control and 50% compression results, and between 25% and 50% compression results. A small nonsignificant increase in latency was observed with increase in contact velocity. The extent of hemorrhagic necrosis correlated with contact velocity rather than with the amount of compression. This study demonstrates, for the first time, a dissociation between hemorrhagic necrosis and loss of neuronal conduction in the subacute phase. Although long-term effects of hemorrhagic necrosis on cord structure and conduction remain to be evaluated, the data suggest that delayed loss of neuronal conduction seen clinically may result from moderate levels of cord compression at high contact velocity. Such an injury is not reproducible by weight-drop techniques for cord injury.

COMPRESSION OF THE SPINAL CORD IN PATIENTS WITH MALIGNANT LYMPHOMA.

The most common neurologic complication of malignant lymphoma is compression of the spinal cord. The seriousness of this complication is somewhat allayed by the high degree of success which customarily follows early diagnosis and treatment. This is one clinical manifestation of malignant lymphoma which should be readily recognized. Usually the earliest symptom is pain, and this paper has been written with the intention of emphasizing (a) the importance of pain in establishing early diagnosis and (b) the success which adequate early treatment ordinarily produces. During the years 1956 through 1962 there were 26 patients with malignant lymphomas at Roswell Park Memorial Institute in whom myelographic and/or spinal fluid dynamics of block were demonstrated as evidence of spinal cord compression. Four of these had two separate compressive episodes at different periods in the course of the disease (interval-average of ten months, median of twenty months, extremes of one and forty months). Williams et al. (1959) reported a large number of cases, but a great many were never proved by myelography to have true epidural tumors. Their monograph does not describe essential radiotherapeutic details. Material Histologic Classification: Of our 26 patients, 14 had Hodgkin's disease, 11, reticulum-cell sarcoma, and 1, lymphosarcoma. This last case was unusual, since it is rare for lymphosarcoma to cause a spinal cord compression syndrome. In this 48-year-old woman, with general manifestations of lymphosarcoma for seven years, two separate levels were involved over a four-month interval. She died ten days after a second compression (C5–D6) because of sepsis (bone-marrow depression, etc.). Sex and Age: There were 16 males and 10 females varying in age from eight to seventy-four years (average, fifty, median, forty-one). The average age for the reticulum-cell sarcoma group was sixty-three with extremes of forty-two and seventy-four (median, fifty-eight), whereas the Hodgkin's disease group had an average age of forty with extremes of eight and sixty (median, thirty-six). Since there was only 1 lymphosarcoma patient (forty-eight years old), data here are meaningless. The eight-year-old girl with Hodgkin's disease gave a three-week history of pain in the lower back and difficulty in walking. Following laminectomy (D5–8) and irradiation (2,100 rads in fourteen days) she showed an excellent result. Although the patient died twenty-one months later of disseminated disease, there was no further trouble from compression of the spinal cord. Diagnosis Level of Cord Compression and Vertebral Bone Involvement: The thoracic vertebral segment was more frequently involved in patients with Hodgkin's disease than in those with reticulum-cell sarcoma. Cord compression was associated with vertebral bone involvement more often when the lumbar vertebrae were infiltrated. This is particularly the case in those patients with reticulum-cell sarcoma.