Electrophysiological Assessment and Classification of Motor Pathway Function in Patients With Spinal Dural Arteriovenous Fistula.

PURPOSE: The diagnosis of spinal dural arteriovenous fistula (SDAVF) is difficult and often delayed because clinical features are often nonspecific. We assessed the motor function electrophysiologically in patients with SDAVF. METHODS: Motor-evoked potentials after transcranial magnetic stimulation and compound muscle action potentials and F-waves after electrical stimulation in the ulnar and tibial nerves were measured from the abductor hallucis (AH) muscles in 14 patients with SDAVF (SDAVF group), 12 patients with compressive thoracic myelopathy (CTM group), and 16 normal subjects (control group). The peripheral conduction time determined from abductor hallucis muscles (PCT-AH) and the central motor conduction time determined from abductor hallucis muscles (CMCT-AH) were calculated. According to the neurological findings, patients in the SDAVF group were classified to upper motor neuron (UMN) sign and lower motor neuron (LMN) sign categories. RESULTS: CMCT-AH in the SDAVF and CMT groups were significantly longer than those in the control group. PCT-AH in the SDAVF group was significantly longer than that in the control and CMT groups. Twelve patients in the SDAVF group showed abnormal CMCT-AH and/or PCT-AH. Abnormal CMCT-AH and PCT-AH were detected in five cases that exhibited UMN sign and/or LMN sign. Three cases with abnormal CMCT-AH and normal PCT-AH exhibited UMN sign. LMN sign without UMN sign was observed in four cases with abnormal PCT-AH and normal CMCT-AH. CONCLUSIONS: Our study revealed abnormalities in the corticospinal tract and/or lower motor neurons, and classified the patients with SDAVF into three types: the UMN type, LMN type, and mixed type.

Use of quantitative assessment scales in cervical spondylotic myelopathy--survey of clinician's attitudes.

BACKGROUND: There is considerable uncertainty regarding the selection criteria of patients and timing of surgery for cervical spondylotic myelopathy (CSM). Attempts have been made to quantify CSM severity using various assessment scales to provide an adjunct to clinical decision-making. The aim of the present study was to determine, by means of a 7-item questionnaire the attitudes of clinicians regarding the importance of quantitative assessment scales in the management of CSM, their actual use in clinical practice and how current scales fall short of the ideal. FINDINGS: Clinical history, examination, radiological imaging and quantitative functional assessment were regarded by 117 clinicians as being almost equally important in the management of CSM. However, only 22 (19%) of clinicians admitted to using an assessment scale in clinical practice and 4 (3%) believed there was a 'gold-standard' assessment scale. These clinicians also considered 'ease of use' to be the most important attribute of an ideal assessment scale, followed by 'reproducibility', 'sensitivity to change' and 'validity'. CONCLUSIONS: The discrepancy between the importance attached to quantitative measurement and its actual use suggests that current scales are under-utilised or unsuitable for clinical practice. A new easy-to use scale may be required that better reflects clinical requirements.

Qualitative assessment of cervical spinal stenosis: observer variability on CT and MR images.

BACKGROUND AND PURPOSE: Several studies have been undertaken to validate quantitative methods of evaluating cervical spinal stenosis. This study was performed to assess the degree of interobserver and intraobserver agreement in the qualitative evaluation of cervical spinal stenosis on CT myelograms and MR images. METHODS: Cervical MR images and CT myelograms of 38 patients were evaluated retrospectively. Six neuroradiologists with various backgrounds and training independently assessed the level, degree, and cause of stenosis on either MR images or CT myelograms. Unknown to the evaluators, 16 of the patients were evaluated twice to determine intraobserver variability. RESULTS: Interobserver agreement among the radiologists with regard to level, degree, and cause of stenosis on CT myelograms showed kappa values of 0.50, 0.26, and 0.32, respectively, and on MR images showed kappa values of 0.60, 0.31, and 0.22, respectively. Intraobserver agreement with regard to level, degree, and cause of stenosis on CT myelograms showed mean kappa values of 0.69, 0.41, and 0.55, respectively, and on MR images showed mean kappa values of 0.80, 0.37, and 0.40, respectively. CONCLUSION: MR imaging and CT myelographic evaluation of cervical spinal stenosis by using current qualitative methods results in significant variation in image interpretation.

Spinal cord compression injury in the mouse: presentation of a model including assessment of motor dysfunction.

The purpose of this study was to develop a spinal cord injury model in the mouse. Various degrees of extradural compression were used to induce mild, moderate or severe compression injuries. Furthermore, a locomotor rating scale was developed by which the functional outcome of the spinal cord injury could be assessed. The introduction of such a model will be useful for further studies on the pathogenesis and treatment strategies of spinal cord injury. To assess hindlimb motor function, a 10-point scale was used. Initially, the animals were allowed to move freely in an open field and were rated 0-5, 0 being no movement and 5 being almost normal. Animals scoring a 5 were then assessed using steel bars with decreasing widths from 2 cm to 5 mm. For each bar successfully crossed over, they gained additional points. Before injury the hindlimb motor function score (MFS) in all the animals was 10. In mice with mild compression, MFS was decreased slightly on day 1 and recovered to 9 +/- 0.6 on day 14. For mice with moderate compression, the MFS decreased to 4.6 +/- 0.4 on day 1 after injury and gradually improved to 8.1 +/- 0.6 on day 14. Severe injury resulted in paraplegia of the hindlimbs day 1 after injury with a score of 0.6 +/- 0.2. By day 14 after injury, these animals gradually recovered to 3.9 +/- 0.1, could bear the weight on the hindlimbs and walk with a severe deficit. There was a 3%, 9% and 19% decrease in the total cross-sectional area of the spinal cord 14 days after mild, moderate and severe injury, respectively. Microtubule-associated protein immunostaining revealed that the gray matter decreased to 61 +/- 7% in moderately injured animals, while severe compression resulted in a complete loss of gray matter. White matter decreased to 86 +/- 6% in moderately injured animals and 29 +/- 11% in severely injured animals. This study shows that the mouse can be used to achieve reproducible spinal cord compression injuries of various degrees of severity. The force of the impact correlates well with the neurological and light microscopic outcome. The motor function test presented in this paper and the computerized quantification of tissue damage can be used to evaluate the efficacy of different treatment strategies.

Cervical cord neurapraxia: classification, pathomechanics, morbidity, and management guidelines.

One hundred ten cases of the transient neurological phenomenon, cervical cord neurapraxia (CCN), are presented. The authors established a classification system for CCN, developed a new computerized measurement technique for magnetic resonance (MR) imaging, investigated the relationship of the cervical cord to the canal, and analyzed clinical, x-ray, and MR data. One hundred nine males and one female were included in the study; the average age of the participants was 21 years (range 13-33 years). All episodes occurred during sports participation; 87% occurred while the patient was playing football. Follow-up review lasting an average of 3.3 years was available for 105 patients (95%). Narrowing of the sagittal diameter of the cervical canal in the adult spine was confirmed to be a causative factor. Cervical cord neurapraxia was not associated with permanent neurological injury and no permanent morbidity occurred in patients who returned to contact activities. Of the patients returning to contact activities, 35 (56%) experienced a recurrent episode. The risk of recurrence was increased with smaller spinal canal/vertebral body ratio (p < 0.05), smaller disc-level canal diameter (p < 0.05), and less space available for the cord (p < 0.05). There was no correlation between either the classification of the CCN episode or the disease noted on MR imaging and x-ray films and the risk of recurrence. The authors conclude that: 1) CCN is a transient neurological phenomenon and individuals with uncomplicated CCN may be permitted to return to their previous activity without an increased risk of permanent neurological injury; 2) congenital or degenerative narrowing of the sagittal diameter of the cervical canal is a causative factor; 3) the overall recurrence rate after return to play is 56%; and 4) the risk of recurrence is strongly and inversely correlated with sagittal canal diameter and it is useful in the prediction of future episodes of CCN (p < 0.001). These data will enable the physician to counsel individuals regarding a predicted risk of recurrence based on canal measurements.