Asymptomatic Nerve Research Articles

Magnetic resonance imaging contribution for diagnosing symptomatic neurovascular contact in classical trigeminal neuralgia: A blinded case-control study and meta-analysis

Although classical trigeminal neuralgia (CTN) is frequently caused by neurovascular contact (NVC) at the trigeminal root entry zone (REZ), both anatomical and MRI studies have shown that NVC of the trigeminal nerve frequently occurs in individuals without CTN. To assess the accuracy of MRI in distinguishing symptomatic from asymptomatic trigeminal NVC, we submitted to high-definition MRI the series of CTN patients referred to our outpatient service between June 2011 and January 2013 (n=24), and a similar number of age-matched healthy controls. Two neuroradiologists, blinded to the clinical data, evaluated whether the trigeminal nerve displayed NVC in the REZ or non-REZ, whether it was dislocated by the vessel or displayed atrophy at the contact site, and whether the offending vessel was an artery or a vein. Our data were meta-analyzed with those of all similar studies published from January 1970 to June 2013. In our sample, REZ contact, nerve dislocation and nerve atrophy were independently associated with CTN (P=.027; P=.005; P=.035 respectively). Compared to a rather low sensitivity of each of these items (alone or in combination), their specificity was high. When REZ contact and nerve atrophy coexisted, both specificity and positive predictive value rose to 100%. Meta-analysis showed that REZ NVC was detected in 76% of symptomatic and 17% of asymptomatic nerves (P<.0001), whereas anatomical changes were detected in 52% of symptomatic and 9% of asymptomatic nerves (P<.0001). In conclusion, trigeminal REZ NVC, as detected by MRI, is highly likely to be symptomatic when it is associated with anatomical nerve changes.

Three-dimensional fast imaging employing steady-state acquisition MRI and its diagnostic value for lumbar foraminal stenosis

The aim of this study was to evaluate the usefulness of three-dimensional (3D) fast imaging employing steady-state acquisition (3D FIESTA) in the diagnosis of lumbar foraminal stenosis (LFS). Fifteen patients with LFS and 10 healthy volunteers were studied. All patients met the following criteria: (1) single L5 radiculopathy without compressive lesion in the spinal canal, (2) pain reproduction during provocative radiculography, and (3) improvement of symptoms after surgery. We retrospectively compared the symptomatic nerve roots to the asymptomatic nerve roots on fast spin-echo (FSE) T1 sagittal, FSE T2 axial and reconstituted 3D FIESTA images. The κ values for interobserver agreement in determining the presence of LFS were 0.525 for FSE T1 sagittal images, 0.735 for FSE T2 axial images, 0.750 for 3D FIESTA sagittal, 0.733 for axial images, and 0.953 for coronal images. The sensitivities and specificities were 60 and 86% for FSE T1 sagittal images, 27 and 91% for FSE T2 axial images, 60 and 97% for 3D FIESTA sagittal images, 60 and 94% for 3D FIESTA axial images, and 100 and 97% for 3D FIESTA coronal images, respectively. 3D FIESTA can provide more reliable and additional information for the running course of lumbar nerve root, compared with conventional magnetic resonance imaging. Particularly, use of 3D FIESTA coronal images enables accurate diagnosis for LFS.

Ultrasound diagnosis of ulnar neuropathy: Comparison of symptomatic and asymptomatic nerve thickness

There is still no consensus on a normal value for the cross-sectional area of the ulnar nerve at the elbow. Such data would be valuable for the ultrasound diagnosis of ulnar neuropathy. Comparison of the symptomatic and contralateral asymptomatic sides has been recommended. The aim of this study was to investigate whether or not the asymptomatic ulnar nerve could be a reference value. High-resolution ultrasonic measurements of the cross-sectional areas of the ulnar nerves at the elbow were compared with 38 contralateral asymptomatic elbows of patients with unilateral ulnar neuropathy and 38 healthy controls. There were significant differences in the cross-sectional areas at all levels between the healthy control subjects and asymptomatic side of the ulnar neuropathy patients (p < 0.05). The findings of this study suggest that there is a limitation in using the asymptomatic side for obtaining reference values in ultrasonographic studies. Each ultrasonographic laboratory should determine its own reference values.

Morphological changes of the epineurium in leprosy: A new finding detected by high‐resolution sonography

From histopathological studies of peripheral nerves in leprosy, it is known that the epineurium can be thickened. We measured the epineurial thickness of the ulnar nerve by high resolution sonography (HRUS). The epineurium of the ulnar nerve was measured above the elbow on transverse scan in 25 healthy controls and 26 leprosy patients. The mean epineurial thickness was 0.77 mm (95% confidence interval [CI] 0.66-0.88) in symptomatic ulnar nerves (n = 20), 0.58 mm (CI 0.51-0.65) in asymptomatic nerves (n = 30), and 0.49 mm (CI 0.44-0.54) in healthy controls (n = 25) (P = 0.0001). This thickening was related to the cross-sectional area of the ulnar nerve, but not with increased blood flow. The epineurium of the ulnar nerve can be measured with the use of HRUS, and it is often strikingly thickened in leprosy patients, especially in those with ulnar involvement.

Radiographic evaluation of trigeminal neurovascular compression in patients with and without trigeminal neuralgia

Neurovascular compression (NVC) of the trigeminal nerve is associated with trigeminal neuralgia (TN), but also occurs in many patients without facial pain. This study is designed to identify anatomical characteristics of NVC associated with TN. Thirty patients with Type 1 TN (intermittent shocklike pain) and 15 patients without facial pain underwent imaging for analysis of 30 trigeminal nerves ipsilateral to TN symptoms, 30 contralateral to TN symptoms, and 30 in asymptomatic patients. Patients underwent 3-T MR imaging including balanced fast-field echo and MR angiography. Images were fused and reconstructed into virtual cisternoscopy images that were evaluated to determine the presence and degree of NVC. Reconstructed coronal images were used to measure nerve diameter and crosssectional area. The incidence of arterial NVC in asymptomatic nerves, nerves contralateral to TN symptoms, and nerves ipsilateral to TN symptoms was 17%, 43%, and 57%, respectively. The difference between symptomatic and asymptomatic nerves was significant regarding the presence of NVC, nerve distortion, and the site of compression (p < 0.001, Fisher exact test). The most significant predictors of TN were compression of the proximal nerve (odds ratio 10.4) and nerve indentation or displacement (odds ratio 4.3). There was a tendency for the development of increasingly severe nerve compression with more advanced patient age across all groups. Decreased nerve size was observed in patients with TN but did not correlate with the presence or extent of NVC. Trigeminal NVC occurs in asymptomatic patients but is more severe and more proximal in patients with TN. This information may help identify patients who are likely to benefit from microvascular decompression.

Severity Analysis of Neurovascular Contact in Patients with Trigeminal Neuralgia: Assessment with the Inner View of the 3D MR Cisternogram and Angiogram Fusion Imaging

Neurovascular contact (NVC) of the trigeminal nerve is not only detected at the affected trigeminal nerve in patients with trigeminal neuralgia (TN) but is also observed at the asymptomatic nerves on the side contralateral to the TN as well as in normal nerves in control subjects. The frequency and severity of the NVC among the affected, contralateral, and normal trigeminal nerves were analyzed by 3D MR cisternogram and angiogram fusion imaging in relation to the cause of TN. The inner view of the fusion MR imaging projected from inside the trigeminal nerve was used. The severity of the NVC was classified as none, simple, moderate, or severe, according to the nerve circumference in contact with the vessel. The NVC was analyzed in the affected nerves (n = 66) and the contralateral nerves (n = 66). Forty patients underwent microvascular decompression surgery, and 26 were treated medically. The NVC at the normal trigeminal nerves (n = 78) was studied in 39 control subjects without symptoms of TN. The NVC in the affected trigeminal nerve was observed more frequently and much more severely than that at the contralateral and normal trigeminal nerves in controls (P < .01). Additionally, the NVC in the surgical patients was more severe than that in the medically treated patients (P < .01). Severity analysis of the NVC with the inner view of the fusion MR imaging may provide useful information in the diagnosis of TN and can be a helpful adjunct in treatment planning for patients with TN.

High-resolution Three-dimensional Magnetic Resonance Angiography and Three-dimensional Spoiled Gradient-recalled Imaging in the Evaluation of Neurovascular Compression in Patients with Trigeminal Neuralgia: A Double-blind Pilot Study

To assess the value of high-resolution three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography and gadolinium (Gad)-enhanced 3D spoiled gradient-recalled imaging in the visualization of neurovascular compression in patients with trigeminal neuralgia. Forty-eight patients with unilateral trigeminal neuralgia underwent high-resolution 3D TOF MR angiography. After administration of a contrast agent, a 3D spoiled gradient-recalled sequence (3D Gad) was run. Images were reviewed by a radiologist blinded to clinical details. All patients underwent microvascular decompression surgery. Microdissection of the trigeminal nerve and compressing vessels was videotaped during surgery and reviewed by surgeons uninvolved in patient care. Results from neuroradiological studies were then compared with findings on operative videotapes. MR angiography in combination with 3D Gad imaging identified surgically verified neurovascular contact in 42 of 46 (91%) symptomatic nerves. The offending vessel (artery, vein) was correctly identified in 31 of 41 cases (sensitivity, 76%; specificity, 75%). Neurovascular compression was observed in 71% of asymptomatic nerves with a trend toward greater compression severity on the symptomatic nerve (P < 0.09). Agreement between the direction of neurovascular contact defined by 3D TOF MR angiography and 3D Gad and findings at surgery was good (kappa = 0.78; 95% confidence interval, 0.61-0.94). Double-blind assessment of surgical and neuroradiological findings confirms that neurovascular compression can be visualized with good sensitivity in patients with trigeminal neuralgia by 3D TOF MR angiography in combination with Gad-enhanced 3D spoiled gradient-recalled sequences. Anatomic relationships defined by this method can be useful in predicting surgical findings.

MRI of the vestibular nerve after selective vestibular neurectomy

Conclusion. In patients with Ménière's disease and persisting vertigo attacks after vestibular neurectomy (VNx) MRI of the vestibulocochlear nerve can identify residual vestibular nerve fibres that could be responsible for the vertigo attacks. Objective. To test if MRI of the vestibulocochlear nerve can corroborate the presence of residual vestibular nerve fibres in patients with persisting vertigo attacks and residual vestibular function after VNx. Materials and methods. Vestibulocochlear nerve bundles of seven post-VNx unilateral Ménière's patients were imaged using 1.5 Tesla MRI with steady state free precession (SSFP) sequences. Reformatted MR images orthogonal to the vestibulocochlear nerve axis in internal auditory canal were compared on the VNx and intact sides. Vestibular function was assessed with caloric tests, three-dimensional head impulse tests and vestibular evoked myogenic potentials. Of the seven patients only one was asymptomatic (totally free of vertigo); six had continued to experience vertigo attacks, albeit not as long or as severe as before VNx. Results. On the VNx side, MRI showed intact facial and cochlear nerves in all seven patients. In the six symptomatic patients, although superior and inferior vestibular nerve bulk and signal were reduced, residual bulk suggestive of inferior vestibular nerve was evident, correlating with evidence of residual posterior canal function on impulsive testing in all six symptomatic patients. In the asymptomatic patient, superior and inferior vestibular nerves were absent on MRI and impulsive testing revealed no residual posterior canal function.

Autoimmune hearing loss in chronic inflammatory demyelinating polyneuropathy

Asymptomatic cranial nerve involvement, most commonly in oculomotor and facial nerves, can be seen in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). It is not always possible to delineate whether cranial nerve abnormalities are related to brainstem or extra axial involvement.1 However, disabling vestibular symptoms on one occasion2 and auditory symptoms on another occasion3 were described and attributed to peripheral nerve demyelination. We describe a patient with CIDP who developed sensorineural hearing loss suggestive of autoimmune inner ear disease (AIED). A 42-year-old previously healthy woman reported distal sensory symptoms in her feet and hands with distal weakness that began 1 year earlier. She also described difficulty hearing with the right ear from onset, which developed suddenly, without tinnitus. She had moderate intrinsic hand muscle, ankle, and toe dorsiflexion weakness. She was areflexic with only vibration deficits up to the ankles. The nerve conduction studies confirmed a demyelinating polyneuropathy with …

Neuropathies

Neuropathies are a significant cause of morbidity worldwide, mainly from diabetes mellitus, HIV infection and leprosy. Many are treatable with immunosuppression or intravenous immunoglobulin. Tight glycaemic control slows progression of diabetic neuropathy. Even when the underlying disorder is untreatable, making a specific diagnosis and appropriate management to avoid complications and neuropathic pain can be rewarding. Neurophysiological studies are crucial in differentiating axonal from demyelinating neuropathies and detecting clinically asymptomatic nerve involvement. With increasing neurophysiological expertise and more widely available genetic testing, the necessity for nerve biopsy as a diagnostic tool has been reduced.

Pure motor mononeuropathy with distal conduction block: an unusual presentation of multifocal motor neuropathy with conduction blocks

Objective: To report an hitherto undescribed presentation of Motor Neuropathy with Multifocal Conduction Block (MMNCB). Methods: Description of two patients presenting with complete paralysis of the 3 heads of the trapezius muscle (case one) and progressive weakness of finger extension (case 2). Results: Nerve conduction studies (NCS) established that the corresponding nerves were distally inexcitable. In the affected muscles, no voluntary activity was elicited in both patients with spontaneous activity noted in patient 2. Systematic NCSs documented an asymptomatic, partial conduction block (CB) in a median nerve forearm segment in both patients. Neurophysiological follow-up after a dramatic response to intravenous immunoglobulins demonstrated recovery of the initially unobtainable motor responses. Conclusions: This indicates that a complete, distal CB of the motor fibers destined to the trapezius muscle in patient 1, and to the extensor indicis proprius in patient 2, had caused the heralding deficits. Significance: These findings underscore the possibility of distal CB in this disorder and the need for extensive NCSs, including asymptomatic nerves, for an accurate diagnosis.

Demonstration of neurovascular compression in trigeminal neuralgia and hemifacial spasm with magnetic resonance imaging: Comparison with surgical findings in 60 consecutive cases

Background Until recently, it has been impossible to demonstrate vascular compression at the root entry or exit zone (REZ) of the trigeminal nerve and facial nerve in patients with trigeminal neuralgia (TN) and hemifacial spasm (HFS) preoperatively, although surgical findings have revealed apparent neurovascular compression and its correction has resulted in a good outcome in most cases. Revealing the anatomic correlation between nerves and vessels at the REZ preoperatively would be useful to predict operative findings. Methods To assess whether the vascular contact of the nerve at the REZ could be demonstrated preoperatively, high-resolution magnetic resonance tomographic angiography (MRTA) was performed in 21 patients with TN and 39 with HFS. Neuroradiological findings were compared with the operative findings in all patients. Contralateral asymptomatic nerves were evaluated as a control. Results MRTA correctly identified offending vessels in 14 (67%) of the 21 TN and 34 (87%) of the 39 HFS patients. Failure to identify neurovascular contact was noted in the cases with compression by veins or small arteries, thickened arachnoid, or distal compression. Neurovascular contact was also observed in 15% of the asymptomatic nerves. The deformity of the nerve seemed to be a more important factor for determining operative indication. Conclusions MRTA could demonstrate offending vessels in TN and HFS at a high rate and was useful to predict operative findings. MRTA gave supportive evidence of surgical indications in patients with TN and HFS, although attention should be paid to the fact that MRTA did not necessarily detect all of the offending vessels.

In vivo anatomical analysis of arterial contact with trigeminal nerve: detection with three-dimensional spoiled grass imaging.

The purpose of this study was to review the normal in vivo neurovascular relationship between the trigeminal nerve and surrounding arteries without the use of volunteers. 290 nerves in 145 cases were reviewed during a 1-year period. Axial source images and multiplanar reconstructed (MPR) images were used to determine the neurovascular contact and direction of contact. Multiplanar volume reformation (MPVR) was used to identify the contact vessels and to demonstrate the relationship between the nerve and arteries. Vascular contact was found in 29% of the 290 nerves (83 nerves). The arteries involved were the superior cerebellar artery (SCA) or the anterior inferior cerebellar artery (AICA). Vascular contact with two arteries was found in 3%. Of the 286 asymptomatic nerves, the nerve was located between the two vessels in 3% and compression was seen in 1%. Three points of vascular contact by the two arteries were identified in one asymptomatic nerve. The direction of contact between the SCA and the nerve was superior (38%), superomedial (32%) or medial (15%) in most cases. The direction of contact between the AICA and the nerve was inferior, inferolateral or lateral in all cases. Vascular contact at the root entry zone (REZ) was noted in 90%. Four nerves were affected by trigeminal neuralgia, one of which touched an artery and two were compressed. It was concluded that arterial contact can be assessed without difficulty but evaluation of vascular compression is not easy.

Intraoperative dermatomal evoked potential monitoring fails to predict outcome from lumbar decompression surgery.

Thirty-three patients with single-level, unilateral lumbosacral radiculopathy underwent micro-decompression 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. 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. 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. 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. 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. 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.

The Study of Visual Evoked Potentials in Patients with Thyroid-Associated Ophthalmopathy Identifies Asymptomatic Optic Nerve Involvement

The Study of Visual Evoked Potentials in Patients with Thyroid-Associated Ophthalmopathy Identifies Asymptomatic Optic Nerve Involvement

MRI of the facial nerve in idiopathic facial palsy.

The purpose of this prospective study was to define the enhancement pattern of the facial nerve in idiopathic facial paralysis (Bell's palsy) on magnetic resonance (MR) imaging with routine doses of gadolinium-DTPA (0.1 mmol/kg). Using 0.5T imager, 24 patients were examined with a mean interval time of 13.7 days between the onset of symptoms and the MR examination. Contralateral asymptomatic facial nerves constituted the control group and five of the normal facial nerves (20.8%) showed enhancement confined to the geniculate ganglion. Hence, contrast enhancement limited to the geniculate ganglion in the abnormal facial nerve (3 of 24) was referred to as equivocal. Not encountered in any of the normal facial nerves, enhancement of other segments alone or associated with geniculate ganglion enhancement was considered to be abnormal and noted in 70.8% of the symptomatic facial nerves. The most frequently enhancing segments were the geniculate ganglion and the distal intracanalicular segment.

SEP-Befunde bei Neuroborreliose

From a European cohort 55 patients with early stage Lyme-neuroborreliosis were tested with somatosensory evoked potentials (SEPs) by stimulating the tibial nerve SEP and/or the median nerve SEP. The tibial SEP seems to be more sensitive in the detection of nerve lesions in clinically symptomatic limbs (67 % versus median SEP: 57 %). With both methodes it was possible to unmask lesions in clinically asymptomatic nerves (tibial SEP: 38 %, median SEP: 30 %). In 16 % of all SEPs we found a combination of lesions in the peripheral and central nervous system, which seems to be specific for Lyme-neuroborreliosis and may help in diagnosing the disease. In our study pathological findings in SEPs proved to be reversible what is of differential diagnostic meaning.

Magnetic resonance imaging of the optic nerve in optic neuritis.

Magnetic resonance imaging (MRI) of the optic nerves using the STIR (short inversion time inversion recovery) sequence was performed in 37 adult patients with a recent or past attack of optic neuritis. MRI revealed high-signal regions in 84% of symptomatic and 20% of asymptomatic nerves. The mean longitudinal extent of lesions was 1 cm. Slow or poor visual recovery was associated with more extensive lesions, or lesions within the optic canal. Disk swelling was usually associated with anterior lesions but also occurred with lesions in the canal. Visual evoked potentials were even more sensitive than MRI in detecting lesions and are still the investigation of choice in suspected demyelinating disease involving the optic nerve.

Cranial Nerve Dysfunction Following Carotid Endarterectomy

In an effort to establish the true incidence of cranial nerve dysfunction after carotid endarterectomy, 50 consecutive carotid endarterectomy procedures were assessed by careful and objective preoperative and postoperative cranial nerve evaluations, including indirect laryngoscopic examination by a trained ENT surgeon. Of the 50 patients evaluated, 2 (4%) were found to have a postoperative cranial nerve deficit, and these were the following: 1 (2%) recurrent laryngeal, none (0%) superior laryngeal, 1 (2%) marginal mandibular nerve, and none (0%) hypoglossal nerve. In no instance was any patient who was asymptomatic found to have unsuspected objective evidence of cranial nerve injury; on the other hand, both symptomatic patients were found to have a significant cranial nerve injury by further evaluation. Our objective data refute the literature that would support a magnitude of either symptomatic or asymptomatic cranial nerve injuries following such a procedure. Our study further fails to support a need for a more extensive exam ination that would routinely include indirect laryngoscopy and a specialist-ori ented consultation—both of which appear neither warranted nor cost effective.