Characteristics of C6-7 myelopathy: assessment of clinical symptoms and electrophysiological findings

An Uncommon Presentation of Cervical Myelopathy

Cervical myelopathy is a compressive spinal cord disease usually affecting individuals 55 and older. Involvement of C5-C7 is typical and classically presents with hand clumsiness, wide-based gait, and paresis. We present the case of a 38-year-old man with a pertinent history of a previous motor vehicle accident who presented to the emergency department for progressive numbness, weakness, and severe spasms in both lower extremities, and eventually developed bowel and bladder incontinence. Lumbar magnetic resonance imaging (MRI) showed moderate L3-L4/L5-S1 degenerative spinal changes; however, cervical MRI demonstrated severe C6-C7 spinal stenosis. The patient did not present with any upper extremity neurological changes. Given the relatively mild changes in the lumbar spine, the patient was concluded to have lower extremity and autonomic neurological issues due to severe cervical spinal stenosis. In this report, we present a relatively common case of cervical myelopathy and myelomalacia in a patient unusually presenting with no upper extremity signs and only lower extremity signs of progressive bilateral leg weakness and neurogenic urinary incontinence. This case emphasizes the importance of considering cervical spine workup in addition to thoracic and lumbar spine and conducting a comprehensive clinical neurological examination in the setting of lower extremity symptoms with progressive bilateral leg weakness and urinary incontinence.

Radiological factors associated with the severity of corticospinal tract dysfunctions for cervical spondylotic myelopathy: An analysis of the central motor conduction time and kinematic CT myelography

Patients with cervical spondylotic myelopathy (CSM) often exhibit symptoms in clinical practice, particularly the elderly, whose lower extremity functions are more likely to deteriorate; however, the underlying mechanisms currently remain unclear. The present study aimed to elucidate the relationship between the neurological severity of CSM based on an electrophysiological examination and radiological findings. Eighty-six patients with CSM were examined using kinematic CT myelography. The cross-sectional area of the spinal cord and dynamic changes in the spinal cord were measured at the affected level. The central motor conduction time (CMCT) using transcranial magnetic stimulation was calculated as follows: motor evoked potential latency - (compound muscle action potential latency + F latency - 1)/2 (ms). A multiple logistic regression analysis was performed to identify the radiological parameters associated with severe lower limb dysfunction. CMCT in the upper limbs correlated with spinal cord compression during neck extension, while that in the lower limbs correlated with a larger C2-7 sagittal vertical axis, cervical lordosis, a small C2-7 range of motion (ROM), and spinal cord compression during neck flexion. In a multiple logistic regression analysis, significant risk factors specific for severe lower limb dysfunction were greater anterior spondylolisthesis during neck extension (P = 0.006, OR: 2.53, 95%CI: 1.13-2.07) and small C2-7 ROM in neutral to flexion (P = 0.035, OR: 0.67, 95%CI: 0.52-0.88). Imaging findings affect upper and lower extremity functions in specific manners. Cervical stiffness or anterior compression factors may be associated with the deterioration of lower limb function.

The associations between radiological and neurological findings of degenerative cervical myelopathy: radiological analysis based on kinematic CT myelography and evoked potentials of the spinal cord

OBJECTIVE

Neurological and imaging findings play significant roles in the diagnosis of degenerative cervical myelopathy (DCM). Consistency between neurological and imaging findings is important for diagnosing DCM. The reasons why neurological findings exhibit varying sensitivity for DCM and their associations with radiological findings are unclear. This study aimed to identify associations between radiological parameters and neurological findings in DCM and elucidate the utility of concordance between imaging and neurological findings for diagnosing DCM.

METHODS

One hundred twenty-one patients with DCM were enrolled. The Japanese Orthopaedic Association (JOA) score, radiological parameters, MRI and kinematic CT myelography (CTM) parameters, and the affected spinal level (according to multimodal spinal cord evoked potential examinations) were assessed. Kinematic CTM was conducted with neutral positioning or at maximal extension or flexion of the cervical spine. The cross-sectional area (CSA) of the spinal cord, dynamic change in the CSA, C2-7 range of motion, and C2-7 angle were measured. The associations between radiological parameters and hyperreflexia, the Hoffmann reflex, the Babinski sign, and positional sense were analyzed via multiple logistic regression analysis.

RESULTS

In univariate analyses, the upper- and lower-limb JOA scores were found to be significantly associated with a positive Hoffmann reflex and a positive Babinski sign, respectively. In the multivariate analysis, a positive Hoffmann reflex was associated with a higher MRI grade (p = 0.026, OR 2.23) and a responsible level other than C6-7 (p = 0.0017, OR 0.061). A small CSA during flexion was found to be significantly associated with a positive Babinski sign (p = 0.021, OR 0.90). The presence of ossification of the posterior longitudinal ligament (p = 0.0045, OR 0.31) and a larger C2-7 angle during flexion (p = 0.01, OR 0.89) were significantly associated with abnormal great toe proprioception (GTP).

CONCLUSIONS

This study found that the Hoffmann reflex is associated with chronic and severe spinal cord compression but not the dynamic factors. The Babinski sign is associated with severe spinal cord compression during neck flexion. The GTP is associated with large cervical lordosis. These imaging features can help us understand the characteristics of the neurological findings.

TMS Correlates of Pyramidal Tract Signs and Clinical Motor Status in Patients with Cervical Spondylotic Myelopathy

BACKGROUND

While the association between motor-evoked potential (MEP) abnormalities and motor deficit is well established, few studies have reported the correlation between MEPs and signs of pyramidal tract dysfunction without motor weakness. We assessed MEPs in patients with pyramidal signs, including motor deficits, compared to patients with pyramidal signs but without weakness.

METHODS

Forty-three patients with cervical spondylotic myelopathy (CSM) were dichotomized into 21 with pyramidal signs including motor deficit (Group 1) and 22 with pyramidal signs and normal strength (Group 2), and both groups were compared to 33 healthy controls (Group 0). MEPs were bilaterally recorded from the first dorsal interosseous and tibialis anterior muscle. The central motor conduction time (CMCT) was estimated as the difference between MEP latency and peripheral latency by magnetic stimulation. Peak-to-peak MEP amplitude and right-to-left differences were also measured.

RESULTS

Participants were age-, sex-, and height-matched. MEP latency in four limbs and CMCT in the lower limbs were prolonged, and MEP amplitude in the lower limbs decreased in Group 1 compared to the others. Unlike motor deficit, pyramidal signs were not associated with MEP measures, even when considering age, sex, and height as confounding factors.

CONCLUSIONS

In CSM, isolated pyramidal signs may not be associated, at this stage, with MEP changes.

TMS Correlates of Pyramidal Tract Signs and Clinical Motor Status in Patients with Cervical Spondylotic Myelopathy

BACKGROUND

While the association between motor-evoked potential (MEP) abnormalities and motor deficit is well established, few studies have reported the correlation between MEPs and signs of pyramidal tract dysfunction without motor weakness. We assessed MEPs in patients with pyramidal signs, including motor deficits, compared to patients with pyramidal signs but without weakness.

METHODS

Forty-three patients with cervical spondylotic myelopathy (CSM) were dichotomized into 21 with pyramidal signs including motor deficit (Group 1) and 22 with pyramidal signs and normal strength (Group 2), and both groups were compared to 33 healthy controls (Group 0). MEPs were bilaterally recorded from the first dorsal interosseous and tibialis anterior muscle. The central motor conduction time (CMCT) was estimated as the difference between MEP latency and peripheral latency by magnetic stimulation. Peak-to-peak MEP amplitude and right-to-left differences were also measured.

RESULTS

Participants were age-, sex-, and height-matched. MEP latency in four limbs and CMCT in the lower limbs were prolonged, and MEP amplitude in the lower limbs decreased in Group 1 compared to the others. Unlike motor deficit, pyramidal signs were not associated with MEP measures, even when considering age, sex, and height as confounding factors.

CONCLUSIONS

In CSM, isolated pyramidal signs may not be associated, at this stage, with MEP changes.

Funicular pain: a case report of intermittent claudication induced by cervical cord compression

Background

Neurogenic origin intermittent claudication is typically caused by lumbar spinal canal stenosis. However, there are few reports of intermittent claudication caused by cervical spinal cord compression.

Case presentation

We present the case of a 75-year-old woman who presented with intermittent claudication. She had a history of lumbar spinal fusion surgery, but there was no sign of lumbar spinal stenosis. She also reported bilateral thigh pain on cervical extension. Electromyogram (EMG), posture-induced test, myelogram, and post-myelogram dynamic computed tomography (CT) were performed. Myelography and post-myelogram dynamic CT in the cervical extension position showed narrowing of the subarachnoid space; the patient reported pain in the front of the both thigh during the procedure. We performed an electromyogram (EMG), which implied neurogenic changes below the C5 level. Based on these results, we diagnosed cervical spinal cord compression and underwent laminoplasty at C4–6 including dome-like laminectomy, which significantly relieved the thigh pain and enabled her to walk for 40 minutes.

Conclusions

In this case, funicular pain presented as leg pain, but was resolved by the decompression of the cervical spinal cord. Funicular pain has various characteristics without any upper extreme symptom. This often leads to errors in diagnosis and treatment. We avoid the misdiagnosis by evaluating post-myelogram dynamic CT compared between flexion and extension. In cases of intermittent claudication, clinicians should keep in mind that cervical cord compression could be a potential cause.

Grip force control during object manipulation in cervical myelopathy

STUDY DESIGN

Cross-sectional research.

OBJECTIVES

To objectively evaluate grip force (GF) control while holding a freely movable object in individuals with cervical myelopathy (CM).

SETTING

Harunaso Hospital, Takasaki, Japan.

METHODS

We studied 52 hands from 26 individuals with CM. Participants performed a grip-and-lift task by pulp pinch using the thumb and index finger before surgery. We monitored individual finger GF (N) during the first 3 s while lifting and holding an object. Correlations between the GF and other clinical tests were evaluated. A multiple stepwise regression analysis was used to examine the contribution of the GF to the severity of clinical symptoms.

RESULTS

Thumb GF was negatively correlated with the 10-s test (rs = -0.32), and index finger GF was positively correlated with its cutaneous pressure threshold (rs = 0.34). Multiple regression for the severity of upper extremity symptoms revealed that the model including the GF had a larger adjusted R² and a lower AIC value than that of conventionally used clinical tests.

CONCLUSIONS

These results suggested that the assessment of individual finger GF control could provide an indicator of the clinical severity of upper extremity in individuals with CM.

Cervical Myelopathy without Symptoms in the Upper Extremities: Incidence and Presenting Characteristics

BACKGROUND

Common signs and symptoms of cervical myelopathy (CM) predominantly manifest in the upper extremities and include hand numbness, hand clumsiness, and distal upper extremity weakness. CM manifesting without symptoms in the upper extremities is rare. This study aimed to better understand the incidence and character of such cases.

METHODS

A retrospective review of surgeries for CM from disc herniation, spondylosis, or ossification of posterior longitudinal ligament over a 12-year period was performed to identify patients presenting without symptoms in the upper extremities.

RESULTS

Of 982 surgically treated patients with CM, 12 (1.2%) had no upper extremity symptoms. All had difficulty ambulating, and 7 of 12 (58%) patients had objective lower extremity weakness. Ten (83%) patients had a history of lumbar degenerative disease. On sensory examination, 4 (33%) patients had a discernible midthoracic pin level, 3 (25%) had loss of sensation from the upper leg and genital area down, and 2 (17%) had only genital/upper thigh area sensory loss. All patients demonstrated neurologic improvement after decompressive surgery.

CONCLUSIONS

Patients with CM may rarely present without symptoms in the upper extremities, presenting with numbness perceived from the upper trunk, waist area, or perineum and legs in addition to leg weakness and gait difficulty. All patients had cervical cord compression at either C5-6 or C6-7 level, accounting for 1% of all patients undergoing cervical surgery. Awareness of this atypical pattern of presentation may aid in clinical assessment of a subset of patients with cervical cord compression.

Utility of the central motor conduction time recorded from the abductor pollicis brevis and the abductor digiti minimi muscles in patients with C6-7 myelopathy

OBJECTIVE

Central motor conduction time (CMCT) recorded from the abductor pollicis brevis (CMCT-APB) and abductor digiti minimi (CMCT-ADM) muscles may enable the evaluation of patients with C6-7 myelopathy. CMCT is more useful for the evaluation of the function of spinal cord than magnetic resonance imaging (MRI) findings. CMCT may be associated with age and height. However, there are few reports regarding CMCT-APB in normal subjects. This study aimed to investigate the relationships between age, height, and conduction parameters in normal subjects to assess the effectiveness of using CMCT-APB and CMCT-ADM for the evaluation of patients with C6-7 and C7-T1 myelopathy.

DESIGN

Retrospective study.

METHODS

Fifteen patients with cervical compressive myelopathy at C6-7 (11 patients) or C7-T1 (4 patients) level were enrolled. The control group consisted of 150 normal subjects (mean age 45.8±17.0 years; mean height 163.6±8.9 cm). Motor evoked potentials induced by transcranial magnetic stimulation and F-waves were used to determine CMCT.

OUTCOME MEASURES

CMCT-APB, CMCT-ADM.

RESULTS

The normative values of CMCT-APB and CMCT-ADM were 5.3±0.7 ms and 5.2±0.8 ms, respectively. CMCT-APB was significantly longer than CMCT-ADM for patients with C6-7 myelopathy (P < 0.05). Neither of the CMCTs for those with C7-T1 myelopathy were significantly different from those of controls, but CMCT-APB was more prolonged than CMCT-ADM in patients with C6-C7 myelopathy.

CONCLUSIONS

CMCTs improve the accuracy of the diagnosis of myelopathy by pinpointing the lesion in combination with MRI imaging. Selective CMCT-APB prolongation may be seen in patients with C6-7 myelopathy but not C7-T1 myelopathy.

The contribution of neurophysiology in the diagnosis and management of cervical spondylotic myelopathy: a review

STUDY DESIGN

Topical review of the literature.

OBJECTIVE

The objective of this review article was to assess indications and usefulness of various neurophysiological techniques in diagnosis and management of cervical spondylogenic myelopathy (CSM).

METHODS

The MEDLINE, accessed by Pubmed and EMBASE electronic databases, was searched using the medical subject headings: 'compressive myelopathy', 'cervical spondylotic myelopathy (CSM)', 'cervical spondylogenic myelopathy', 'motor evoked potentials (MEPs)', 'transcranial magnetic stimulation', 'somatosensory evoked potentials (SEPs)', 'electromyography (EMG)', 'nerve conduction studies (NCS)' and 'cutaneous silent period (CSP)'.

RESULTS

SEPs and MEPs recording can usefully supplement clinical examination and neuroimaging findings in assessing the spinal cord injury level and severity. Segmental cervical cord dysfunction can be revealed by an abnormal spinal N13 response, whereas the P14 potential is a reliable marker of dorsal column impairment. MEPs may also help in the differential diagnosis between spinal cord compression and neurodegenerative disorders. SEPs and MEPs are also useful in follow-up evaluation of sensory and motor function during surgical treatment and rehabilitation. EMG and NCS improve the sensitivity of cervical radiculopathy detection and may help rule out peripheral nerve problems that can cause symptoms that are similar to those of CSM. CSP also shows a high sensitivity for detecting CSM.

CONCLUSION

Neuroimaging, especially magnetic resonance imaging, represents the procedure of choice for the diagnosis of CSM, but a correct interpretation of morphological findings can be achieved only if they are correlated with functional data. The studies reported in this review highlight the crucial role of the electrophysiological studies in diagnosis and management of CSM.