Ultrasonography shows extensive nerve enlargements in multifocal motor neuropathy

Using ultrasonography we found multiple sites with nerve enlargement along the course of the brachial plexus, median, ulnar, and radial nerves in the majority of 21 patients with multifocal motor neuropathy. Sonography and electrophysiologic studies showed more abnormalities than expected on purely clinical grounds. Moreover, sonography revealed nerve enlargement without clinical or electrophysiologic abnormalities.     

Short-segment nerve conduction studies in ulnar neuropathy at the elbow

The aim of the study was to assess the diagnostic value of short-segment nerve conduction studies (NCS) at 2-cm intervals from 4 cm above to 4 cm below the medial epicondyle in a large group of patients with ulnar neuropathy at the elbow (UNE). Furthermore, we wanted to compare electrodiagnostic and clinical findings. We evaluated 73 arms in 70 patients with UNE and observed the following abnormalities on short-segment NCS: focal conduction block (CB) in 1, focal CB with increased latency change in 34, and increased latency change alone in 25. Short-segment NCS had an additional localizing value in 28 arms of the 37 patients (76%) with motor conduction velocity (MCV) slowing across the elbow only or with nonlocalizing electrodiagnostic findings. The lesion was located above the elbow in 32 arms (53%), at the epicondyle in 16 arms (27%), and below the epicondyle in 12 (20%) of the 60 arms with focal CB or increased latency change on short-segment NCS. Patients with CB on routine and short-segment NCS had muscle weakness significantly more often than patients without CB. Thus, short-segment NCS are useful in localizing the lesion in patients with UNE and CB on routine NCS and have additional diagnostic value in patients with MCV slowing across the elbow or with nonlocalizing signs on routine nerve conduction studies. We recommend its use in all patients in whom UNE is suspected.     

Multifocal motor neuropathy with persistent conduction blocks: 18 years on

Multifocal motor neuropathy with persistent conduction blocks was firstly reported in 1986 and outlined from the group of purely motor diseases of the peripheral nervous system. The main criterion is the presence of conduction blocks located only on the motor nerves; additionally 30 percent of patients have IgM subclass serum antibodies directed against GM1 ganglioside. The clinical picture is a multifocal, asymmetrical, neuropathy, starting and predominant in the upper limbs, occurring in males aged 50 years and more, and having a progressive course. There is no biological sign besides elevated anti-GM1 antibodies. CSF analysis discloses mild increased protein count. The course is unpredictable, the neuropathy may be strictly limited to one or two motor nerves, or spread to other motor nerves in the four limbs. There is no involvement of the sensory and the cranial nerves, no involvement of the autonomic and the central nervous system. The pathophysiology is unknown, animal models do not allow to confirm the role of humoral immunity, and the role of anti-GM1 antibodies is controversial. Randomized controlled trials have assessed the efficacy of intravenous immunoglobulins which dramatically improve strength in 70-80 percent of patients in the short term, but remain unable to prevent motor deterioration in most patients, together with the occurrence of new conduction blocks. Corticosteroids and plasma exchanges do not improve the patients and may be followed by transient worsening. Long-term efficacy of immunosuppressive agents is not known.     

Ultrasonography of the tibial nerve in vasculitic neuropathy

Ultrasonography is a new imaging method for visualizing peripheral nerves. In vasculitic neuropathy, pain or axonopathy often can prevent the lesion from being localized during electrophysiological examinations, but the ability of ultrasonography to evaluate it morphologically is unknown. Our aim was to determine whether ultrasonography could be used to detect abnormalities in tibial vasculitic neuropathy at the medial ankle. We evaluated 11 tibial nerves in 8 patients with tibial vasculitic neuropathy, and 35 tibial nerves in 35 control subjects. In the controls, the tibial nerve was successfully visualized as a hyperechoic nodule with multiple round hypoechoic areas transversely; in the patients, the tibial nerve appeared enlarged and hypoechoic. The affected nerve area was significantly larger (13.5 +/- 3.7 mm(2)) than in controls (7.2 +/- 1.5 mm(2)). Our results suggest that ultrasonography is a useful neuroimaging method for evaluation of tibial vasculitic neuropathy, especially when nerve conduction study findings are inconclusive.     

Ultrasonography of ulnar neuropathy at the elbow: Axonal involvement leads to greater nerve swelling than demyelinating nerve lesion

ObjectiveTo evaluate nerve size parameters measured by ultrasound in patients with ulnar neuropathy at the elbow (UNE) and to correlate them with the type of nerve lesion.MethodsThe largest cross sectional area (CSA_max) of the ulnar nerve around the elbow and the cubital-to-humeral nerve area ratio (CHR) were measured in 50 elbows with UNE and in 87 elbows of 50 healthy subjects. CSA_max and CHR were compared between controls and patients with predominantly demyelinative and axonal nerve involvement. Subgroups of patients with pure sensory and mixed sensorimotor axonal lesion were also compared.ResultsIn patients with axonal nerve involvement, a significantly larger CSA_max and CHR were found when compared to those with predominantly demyelinating nerve lesion; both groups differed significantly from healthy controls. CSA_max values in patients with sensorimotor axonal lesion were significantly higher than in those with pure sensory axonal involvement.ConclusionCSA_max and CHR highly correlate with the type of nerve pathology in UNE, with a significantly larger nerve swelling seen in axonal lesions, as compared to demyelinating lesions.SignificanceIn addition to helping in the localization of nerve lesion, ultrasonography may also reflect the type and degree of nerve lesion as assessed by electrophysiological means.     

Segmental mixed nerve conduction studies in ulnar neuropathy at the elbow.

Conventional nerve conduction and electromyography may not be adequate in localizing ulnar neuropathy at the elbow, particularly in longstanding lesions with severe axon loss. Ratios of wrist to elbow and elbow to axilla segmental ulnar mixed nerve amplitudes were determined in 11 patients with ulnar neuropathy at the elbow. In 20 control subjects, the mean ratio was 1.06 +/- 0.25 (standard deviation). All patients had ratios less than two standard deviations of the control mean ratio. This method is a useful adjunct to conventional nerve conduction techniques in the localization of ulnar neuropathy at the elbow.     

Sensory nerve conduction in the upper limbs at various stages of diabetic neuropathy

In 59 diabetic patients, sensory nerve potentials were recorded at various sites along the course of the median nerve. Pathological responses were characterized by reduced amplitude, desynchronization and decreased conduction velocity (CV). Four groups of patients with increasingly severe nerve dysfunction were distinguished. The presence and severity of clinical neuropathy in the upper limbs could be related to decreased maximal sensory nerve CV in the proximal segment of the limbs. When maximal sensory nerve CV was normal above the wrist, neuropathy usually remained latent. In severe cases where no sensory nerve potentials could be recorded, the cerebral evoked potentials nonetheless permitted a precise evaluation of the somatosensory conduction. In these cases, maximal sensory nerve CV was very low. In five patients with a so-called diabetic mononeuropathy, abnormal nerve potentials were recorded in the median nerve, although no clinical signs could be seen in the corresponding territory. It is proposed that the diabetic nature of a mononeuropathy can be assessed by the finding of latent abnormalities in seemingly normal nerve.     

糖尿病周围神经病运动神经传导速度分布

目的分析早期糖尿病周围神经病运动神经传导速度分布特点。方法对60例早期糖尿病周围神经病患者进行临床观察及神经系统查体,常规测定运动及感觉神经传导速度,运用计算机辅助对冲方法测定运动神经传导速度分布范围,并与10名健康志愿者的检测结果进行比照。结果正中神经最慢速度(CV10%)为(46.7±5.7)m/s、中等速度(CV50%)为(50.6±5.2)m/s、最快速度(CV90%)为(53.4±5.0)m/s;尺神经CV10%为(47.4±5.6)m/s、CV50%为(51.6±5.3)m/s、CV90%为(55.0±5.4)m/s;腓总神经CV10%为(34.9±5.4)m/s、CV50%为(39.2±4.6)m/s、CV90%为(42.7±4.7)m/s。除正中神经和尺神经的CV10%及所有检测神经的CV50%外,60例患者与健康人的结果均数比较差异有统计学意义。结论运动神经速度分布峰值左移,各级速度纤维传导均减慢。各级纤维非均匀损害,快传导速度纤维优先受累最常见。运动神经速度分布检测比常规运动传导测定更敏感、稳定,可用于糖尿病周围神经病早期诊断和发现亚临床病变。     

Sensory and mixed nerve conduction studies in the evaluation of ulnar neuropathy at the elbow

The relative sensitivities of sensory, mixed nerve, and motor conduction studies in assessing ulnar neuropathy at the elbow have not yet been established. Using surface electrodes, we performed conduction studies across the elbow segment in 43 patients with symptoms referable to the ulnar nerve and 40 control subjects. Segmental slowing of motor conduction localized the lesion to the elbow in 14 of 21 patients (67%) with clear evidence of ulnar neuropathy on physical examination but only in 2 of 22 (9%) with subtle or no physical examination abnormalities. The diagnostic yield was increased by the finding of segmental slowing of sensory or mixed nerve conduction across the elbow to 86% and 68%, respectively, for each of the groups. We conclude that surface-recorded sensory and mixed nerve conduction studies appear to be more sensitive than motor studies in the electrodiagnosis of ulnar neuropathy at the elbow and are especially valuable in patients with subtle clinical involvement. © 1994 John Wiley & Sons, Inc.     

The effects of 4-aminopyridine on focal nerve conduction block

In order to test whether 4-aminopyridine (4-AP), a potassium channel blocker, may be of therapeutic value in demyelinating neuropathies, a focal tibial nerve conduction block with demyelination was produced in adult rats by an intraneural microinjection of potassium tellurite. Onset and recovery of the lesion were monitored by evoked compound muscle action potentials (CMAP) activated from the proximal and distal nerve one day before and 1, 4, 7, 14, 21 and 28 days after the injection. Intraperitoneal 4-AP (2 mg/kg) or buffered saline were injected prior to the potassium tellurite and 6 days per week for 28 days. The data show that 4-AP is tolerated, it does not prevent conduction block, and only has a modest effect on increasing its recovery from day 4 to 7 (91 % increase in CMAP ratio compared with control of 35%). Recovery is similar by day 28 in 4-AP treated or untreated animals. These results suggest that 4-AP will have limited use in the therapy of subacute demyelinating neuropathies.