Clinical and Neurophysiological Assessment of Cervical Radiculopathy

Transcription

1 Mohamed El-Khatib et al. Clinical and Neurophysiological Assessment of Cervical Radiculopathy Mohamed G. El-Khatib 1, Mohamed Saad 1, Seyam Saeed 2, Mohamed El-Sayed 1 Departments of Neurology, Mansoura University 1, Neurophysiology, Cairo University 2 ABSTRACT Background: Neurophysiological studies may aid in the assessment of cervical radiculopathy. Objective: The aim of this study is to evaluate the different clinical presentations and to assess the role of neurophysiological studies in patients with cervical radiculopathy. Methods: 46 patients with cervical radiculopathy in addition to 16 age- and sex- matched control subjects were subjected to thorough neurological history taking, complete neurological examination, laboratory investigations, plain X- Ray and MRI of the cervical spine in addition to neurophysiological investigations in the form of needle electromyography, motor and sensory conduction studies, F-response and somatosensory evoked potential of the median nerve. Results: MRI and needle EMG showed highest sensitivity for diagnosing cervical radiculopathy while motor and sensory conduction studies, F-wave and SEPs showed no statistically significant differences between patients and control. Conclusion: We concluded that neurophysiological studies and MRI remain complementary modalities in the evaluation of cervical radiculopathy. (Egypt J. Neurol. Psychiat. Neurosurg., 2006, 43(1): ) INTRODUCTION Cervical radiculopathy is a pathologic process involving the cervical nerve roots. It is the result of compression and/or inflammation of the nerve root or roots at or near the cervical neural foramen 1. It occurs at an annual incidence rate of 85 per The cardinal manifestation of cervical radiculopathy is pain radiating in a dermatomal distribution. 1 Although it is believed to be the imaging method of choice in the evaluation of cervical radiculopathy, MRI abnormalities have also been found in asymptomatic subjects. Ten present of subjects younger than 40 years, were noted to have disc herniations in one study. Of subjects older than 40 years, 20% had disc protrusion or herniation, therefore, as with all imaging studies, the MRI findings must be used in conjunction with history and physical examination findings. 2 Needle electromyographic examination remains the most widely accepted method for the electrodiagnostic evaluation of radiculopathies. 3,4 Despite the high sensitivity claimed for needle electromyography (NEMG) in the evaluation of radiculopathies, there are practical and theoretical reasons for the need for additional electrodiagnostic studies. Overlapping abnormalities due to polyneuropathies or focal nerve injuries need to be excluded. 5 Depending on the underlying pathophysiology, abnormalities may occasionally be seen on routine motor studies in cervical radiculopathies. If the pathophysiology is predominantly demyelinating, any motor study, stimulating and recording distally, will show a normal latency, conduction velocity. If the pathophysiology also involves axonal loss, this may result in a decreased CMAP amplitude, with some slowing of conduction velocity and distal latency. 6 Normal sensory nerve action potentials (SNAPs) are considered strong evidence for a 109

2 Egypt J. Neurol. Psychiat. Neurosurg. Vol. 43 (1) Jan 2006 cervical radiculopathy versus more distal (plexus or nerve) injury. This is true since in radiculopathies injury has been considered to occur proximal to the dorsal root ganglia (DRG). Nerve fiber degeneration would therefore occur centrally rather than distally with preservation of normal SNAPs. 5 Because F-waves assess conduction both distally and proximally, abnormal F-response with normal distal conduction studies suggest proximal lesions in the roots. Unfortunately, from a practical point of view, their usefulness in the diagnosis of cervical radiculopathy is limited. 6 If radiculopathy predominantly affects sensory nerve root fibers (as often occurs) the F-response, which measures motor fibers, will be normal. Somatosensory evoked potential (SEP) may provide valuable information on the physiological status of the disease involving the common cervical levels, with predominant or even isolated sensory abnormalities. 7 SUBJECTS AND METHODS Subjects: This study included 46 patients with cervical radiculopathy due to cervical spondylosis. A control group of 16 age-and sex-matched clinically free volunteers were included. We excluded from this study patients with cervical radiculomyelopathy, patients with clinical or neurophysiological evidence of polyneuropathy, patients with symptoms less than 3 weeks duration and patients with diabetes, liver, renal or any other systemic disease. Methods: All patients were subjected to 1. Thorough neurological history taking. 2. Complete neurological examination. 3. Laboratory investigations: complete blood picture, fasting and postprandial blood sugar, liver and kidney function tests. 4. Radiological investigations. A. Plain x-ray cervical spine: Anteroposterior, lateral and oblique views. B. MRI of the cervical spine. 5. Neurophysiological investigations: a. Needle electromyography (NEMG): Was performed with bipolar concentric needle electrodes for the following muscles: Biceps (C6), Triceps (C7), Deltoid (C5), Abductor polices brevis (C8-T1) and abductor digiti minimi (C8-T1) on the radiculopathy side. b. Nerve conduction studies: Motor and sensory conduction studies for both median and ulnar nerves on the radiculopathy side were performed. Distal latency, amplitude of the response and conduction velocity were determined. c. F- response: The minimal and the mean F- wave latency was recorded for the median and ulnar nerves at the abductor pollicis brevis and abductor digiti minimi muscles respectively. d. Somatosensory evoked potential (SEP) of the median nerve: SEP of the median nerve was recorded for 10 patients and 10 age-and sexmatched controls. Recording electrodes was placed over Erb s point (EP), second cervical spinous process (CX) and contralateral scalp at C3 and C4 (2 cm posterior to the C3 and C4 position of the international system of EEG electrode placement). Stimulating electrodes were in the form of bipolar disc electrodes placed at the median nerve. Absolute latency, interpeak latency and amplitude of the response were determined. RESULTS I. Clinical results: 1. Age: ranged from 32 to 75 year with a mean of 47 years. 2. Sex: There were 29 (63%) males and 17 (37%) females. 110

3 Mohamed El-Khatib et al. II. 3. Duration of illness: ranged from 1.5 months 5.0 years with a mean of 1.6 years. 4. Complaint: the sensory symptoms were present in all patients while motor symptoms were present in 34.0% of patients. 5. Muscle wasting: Muscle wasting was present in 11 (32.9%) patients most commonly in Triceps muscle (in % patients). 6. Muscle Tone: Hypotonia around elbow was present in 9(19.6%) patients while muscle tone around wrist was intact in all cases. 7. Muscle power: Muscle weakness was present in 30 (65.2%) patients most commonly in Triceps muscle in 15 (32.6%) patients Followed by Biceps muscle in 10 (21.7%) and Deltoid muscle 5 (10.9%) patients. 8. Deep tendon reflexes in upper limb: Hyporeflexia was present in 27(58.7%) patients most commonly in Triceps reflex followed by Biceps and Brachioradialis reflexes. 9. Sensory examination: Radicular sensory loss was present in C5 in 19(30.4%) patients, in C6 in 25 (54.3%) patients, in C7 in 32 (69.6%) patients and in C8 in 1 (2.2%) patients. Radiological Results: 1. Plain x-ray cervical spine: Straight cervical curve was present in 21 (45.7%) patients, narrowing of disc spaces was most common at C6-7 disc (in % patients), narrowing of intervertebral foramina was present in 19(41.3%) patients and spondylotic changes were present in 27 (58.7%) patients. 2. MRI cervical spine: a. Affected disc levels: The incidence of disc prolapse was as follows: C4-5 in 17 (37%) patients, C5-6 in 27 (45.7%) patients, C6-7 in 35 (76.1%) patients, C7-8 in 1 (2.2%) patient. b. Root compression: Root compression was present in 22(37.8%) patients. III. Neurophysiological results: 1. Needle electromyography: NEMG showed prolonged insertional activity in 5 (10.9%) patients most commonly in Triceps muscles. Decreased recruitment was present in 17 (37%) patients, Abnormal spontaneous activity (in the form of fibrillations and fasciculations) was present in 20 (43.5%) patients most commonly in Triceps muscles. Reinnervation potentials were also detected in the form of increased duration of MUAP (in 45.7% patients), increased amplitude of MUAP (in % patients) and increased polyphysicity (in % patients). 2. Nerve conduction studies (NCSs): There were no statistically significant differences between patients and control as regard motor and sensory conduction studies of both median and ulnar nerves (p> 0.05). 3. Results of F-wave: There were no statistically significant differences between patients and control as regard mean F-wave latency of both median and ulnar nerves (p>0.05). 4. Results of SEPs: Prolonged N13 absolute latency and N9- N13 interpeak latency was present in 4 patients (40% of patients subjected to SEP study). However this prolongation was not statistically significant when compared with the control group. (p> 0.05). IV. Correlations: A. Correlation between clinical and EMG results: 1. Age of the patients: No statistically significant correlations was found between age and EMG results (p>0.05). 111

4 Egypt J. Neurol. Psychiat. Neurosurg. Vol. 43 (1) Jan Sex of the patients: There was a statistically significant correlation between sex of the patients and EMG results (p< 0.05). 3. Duration of illness: No statistically significant correlation was detected between the duration of illness and EMG results. (p>0.05). 4. Muscle power: There was a statistically significant correlation between muscle power and EMG results (p< 0.05). B. Relation between EMG and MRI Results: The sensitivity of EMG was 65.2% while the sensitivity of MRI was 89.1%. The two studies agreed in the majority (71.6%) of patients with both normal in 8.6% and both abnormal in 63%. In 13 (28.5%) patients only one study was abnormal. C. Relation between Root Compression in MRI and EMG Results: It was found that 16 patients with MRI showing root compression had positive EMG results of cervical radiculopathy while 10 patients without root compression had positive EMG results of cervical radiculopathy. D. Relation between Radicular Sensory Loss and SEP Results: In patients with radicular sensory loss, it was found that 66.7% had SEP abnormalities while in patients without radicular sensory loss, it was found that only 28.57% had SEP abnormalities. Table 1. Needle electromyography. NEMG 1- Prolonged insertional activity 2- Abnormal spontaneous activity 3- Decreased recruitment 4- Increased duration of MUAP 5- Increased amplitude of MUAP 6- Increased polyphysicity A.P.B.: Abductor pollicis brevis, A.D.M.: Abductor digiti minimi. Muscle Triceps Biceps Deltoid A.P.B A.D.M No % No % No % No % No % No %

5 Mohamed El-Khatib et al. Table 2. Median nerve conduction study. Cases Control (Mean±S.D.) (Mean±S.D.) P 1- Median nerve motor conduction study. - DL - MCV - AMP 3.4 ± ± ± ± ± ± Median nerve sensory conduction study. - DL - SCV - AMP 2.4 ± ± ± ± ± ± DL: Distal latency, MCV: motor conduction velocity, AMP: Amplitude, SCV : sensory conduction velocity. Table 3. Ulnar nerve conduction study. Cases (Mean±S.D.) Control (Mean±S.D.) P 1- Ulnar nerve motor conduction study. - DL 2.7 ± ± MCV 65.8 ± ± AMP 7.3 ± ± Ulnar nerve sensory conduction study. - DL 2.2 ± ± SCV 52.2 ± ± AMP 23.8 ± ± Table 4. Comparison between patients and control regarding F- wave latency. Cases Control Mean ± S.D Mean ± S.D P Median ± ± Ulnar ± ±

6 Egypt J. Neurol. Psychiat. Neurosurg. Vol. 43 (1) Jan 2006 Table 5. Correlation between age, sex, duration and muscle power and EMG results. Age Sex Duration Muscle power < 40 year > 40 year Male Female < 1 year > 1 year Weakness Intact EMG -ve +ve No 3 3 % No % No % No 1 16 % No 3 11 % No % No 1 15 % No % P Table 6. The relation between EMG and MRI results among studied patients. No % EMG positive MRI positive Both positive Both negative One positive Table 7. Relation between root compression in MRI and EMG results. MRI EMG positive negative Disc prolapse with root No 16 6 compression % Disc prolapse without root No compression % P 0.03 Table 8. The relation between radicular sensory loss and somatosensory evoked potential. Sensory examination Radicular sensory loss Intact No % No % -ve SEP +ve

7 Mohamed El-Khatib et al. MRI of a patient showing C6 and C7 disc protrusion SEP of a patient showing delayed N13 latency, prolonged N9-N13 interpeak latency and decrease N13 amplitude. 115

8 Egypt J. Neurol. Psychiat. Neurosurg. Vol. 43 (1) Jan 2006 DISCUSSION MRI has been found to be helpful in the diagnosis of spinal cord and root compression. However, MRI may show abnormalities at the level of cord and root compression, but gives no information about the function of the cord and root. 8 Neurophysiological studies are commonly used in lower motor neuron evaluation. These studies are extensions of the neurologic examination and provide an objective measure of nerve damage. They can confirm the clinical impression of nerve root compression and document or exclude other illnesses of nerves or muscles that could contribute to the patient s symptoms and signs. 9 In our study, the most common symptoms of cervical radiculopathy were neck pain with radicular arm pain which were present in all cases while 16 patients (34%) only complained of arm weakness. The most common neurological signs were sensory deficits (80%), muscle weakness (65.2%), reflex deficits (58.7%), muscle wasting (23%) and hypotonia (19.6%). This is in agreement with Henderson et al. 10, study who reviewed the clinical presentation of cervical radiculopathy in over 800 patients and found sensory deficits in 85.2%, motor deficits in 68% and reflex deficits in 71.2% of patients. MRI of the cervical spine showed disc prolapse at C6-7 disc in 76.1% of patients followed by C5-6 disc in 45.7% followed by C4-5 disc in 37% then by C7-D1in 2.2% of patients. MRI showed also root compression in 22 (37.8%) patients. Brown et al. 11, in a blinded, retrospective review, studied 34 patients who underwent MRI prior to surgery.mri correctly predicted 88% of lesions on opposed to 81% for CT myelography, 57% for plain myelography, and 50% for CT. In our NEMG study, abnormal; spontaneous activity was found in 20 cases (43.5%) most commonly in Triceps muscle (39.1%) followed by biceps (21.7%). This is in agreement with Levin et al. 12, who found abnormal spontaneous activity in C7 radiculopathy in 56% of patients followed C6 radiculopathy in 18% patients. Prolonged duration of MUAP was present in 21 patients (45.7%), increased polyphysicity in 20 patients (43.5%), increased amplitude in 8 patients (17.44%) and decreased recruitment in 17 patients (37%). These signs of chronic denervation were found to be more frequent in C7 radiculopathy followed by C6 and C5. This is in agreement with Katirji et al. 13 study on 20 patients with cervical radiculopathy who found the root involvement using EMG to be most frequent in C7 (45%) followed by C6 (30%) and C5 (15%). Motor and sensory conduction studies were normal in our study with no statistically significant differences between the patients and control. Although motor and sensory conduction studies are usually normal in cervical radiculopathies, they are essential part of their diagnostic evaluation. Mononeuropathies, polyneuropathies and plexopathies may all need to be excluded before an electrodiagnostic diagnoses of radiculopathies can be made These all require relevant motor and sensory conduction studies. 5 In our study, the mean F-wave latencies for the median and ulnar nerves were normal. No statistically significant differences were found between the patient and control. This is in agreement with Tackman and Radu 14 study on 20 patients who had clinical symptoms and/or signs of compression of the 7 th and/or 6 th cervical roots. F-wave conduction velocities were found to be normal. In our study, the most sensitive SEPs abnormalities were prolonged N9-N13 interpeak latency and longed N13 latency however the mean values were statistically insignificant compared to controls (p> 0.05). This is in agreement with Ganes 15 study who found normal cervical SEPs in patients with pure sensory symptoms caused by cervical spondylosis. In patients with objective radicular signs, the most important finding were increased N9- N13 interpeak latency in the median SEP. There was no significant correlation in our patients between the age of the patients and EMG results. This is in agreement with Saeed et al. 16 study on 25 patients with cervical spondylotic radiculopathy. In our study, there was significant correlation between the sex of the patients and EMG findings (p=0.002) where 94% of female patients showed EMG abnormalities while only 48.3% of male patients showed EMG abnormalities. These findings were in contrast to 116

9 Mohamed El-Khatib et al. Saeed et al. 16 study on cervical radiculopathy who found no significant differences between males and females. This can be explained by the fact that in our study, the incidence of motor deficit was higher in female patients which made denervation and subsequent reinnervation more common with more EMG abnormalities than male patients. There was statistically significant correlation between muscle weakness and EMG abnormalities where 93.3% of patients with muscle weakness showed EMG abnormalities while only 50% of patients without muscle weakness showed EMG abnormalities. This is in agreement with Nardin et al. 17 study who found EMG abnormalities in 72% of patients with abnormal findings on neurologic examination. There was significant correlation between MRI and EMG abnormalities. EMG abnormalities were found in 65.2% of patients and MRI abnormalities in 89.1%. The two studies agreed in the majority (71%) of patients. This is in agreement with Nardin et al. 17, who found that 55% of patients had EMG abnormalities and 57% had MRI abnormalities. Both EMG and MRI agreed in 60% pf patients. There was statistically significant differences (p<0.05) between patients with MRI evidence of root compression and those without root compression as regard EMG results. Out of 22 patients with root compression, there were 16 (72.7%) patients with positive EMG results but out of 24 patients without root compression, only 10 (41.7%) patients had positive EMG results. In our study, abnormalities in SEPs varied according to clinical presentation. Patients with cervical radiculopathy with radicular sensory loss showed SEPs abnormalities more than patients without radicular sensory loss. This is in agreement with Yiannikias et al. 18, who found no SEPs abnormalities in patients with cervical spondylosis presented with neck pain alone while SEPs abnormalities were present in 60% of patients with cervical radiculopathy with radicular sensory deficits. In conclusion, our study suggests that neurophysiological studies and MRI remain complementary modalities in the evaluation of cervical radiculopathy. The most sensitive electrodiagnostic test was found to be needle electromyography which showed signs of denervation and reinnervation. The motor conduction studies, the sensory conduction studies and F-wave were all within normal, yet they remain important for exclusion of peripheral nerve disease as a potential cause of denervation changes. Somatosensory evoked potential have little value in the evaluation of isolated root lesions. REFERENCES 1. Abbed K.M. and Coumans J.V. (2003): Cervical radiculopathy: Pathophysiology, presentation, and Clinical evaluation, review article, Department of neurosurgery, Massachusetts General hospital, Harvard medical school, Boston Massachusetts. pp. 1-28(Medline) 2. Malarga G. A. (2001): Cervical radiculopathy. Medicine journal. October; 5(2): Dumitru D. (1995): Electrodiagnostic medicine, Philadelphia, Hanley and Belfus, pp: Wilbourn A.J. and Aminoff M.J. (1998): The electrodiagnostic examination in patients with radiculopathies. Muscle Nerve; 12: Fisher M.A. (2002): Electrophysiology of radiculopathies, Clin neurophysiol. Mar; 113(3): Preston D.C., Shapiro B.E. and Kelly J.J.(1998): Electromyography and neuromuscular disorders. Clinical. Electrophysiological correlation. Ed1. Butterworth-Heinemann. 7. Oh S.J. (2003): Clinical electromyography and nerve conduction studies. 3 rd ed. Lippincotl. Williams and Wilkins. 8. Hashimoto T., Uozumi T. and Tsuji S. (2000): Paraspinal motor evoked potentials by magnetic stimulation of the motor cortex. Neurology, Sep 26; 55(6): Borenstein D.G., Wiesel S.W and Boden S.D. (2004): Low back and neck pain. Comprehensive diagnosis and management 3rd ed. Elsevier, Inc., USA. Chapter 8: pp: Henderson C.M., Hennessy R.G., Shuey H.M. and Shacelford E.G. (1983): Posterior lateral foraminotomy as an exclusive operative technique for cervical radiculopathy: a review of 846 consecutively operated cases. Neurosurgery; 13:

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