Somatosensory evoked potentials in the assessment of peripheral neuropathies: Commented results of a survey among French-speaking practitioners and recommendations for practice.

BACKGROUND: Somatosensory evoked potentials (SSEPs) are increasingly performed for the assessment of peripheral neuropathies, but no practical guidelines have yet been established in this specific application. STUDY AIM: To determine the relevant indication criteria and optimal technical parameters for SSEP recording in peripheral neuropathy investigation. METHODS: A survey was conducted among the French-speaking practitioners with experience of SSEP recording in the context of peripheral neuropathies. The results of the survey were analyzed and discussed to provide recommendations for practice. RESULTS: SSEPs appear to be a second-line test when electroneuromyographic investigation is not sufficiently conclusive, providing complementary and valuable information on central and proximal peripheral conduction in the somatosensory pathways. CONCLUSIONS: Guidelines for a standardized recording protocol, including the various parameters to be measured, are proposed. CLINICAL RELEVANCE: We hope that these proposals will help to recognize the value of this technique in peripheral neuropathy assessment in clinical practice.

Insidious peripheral neuropathy occurring under treatment in infantile MTHFR deficiency.

5,10-Methylenetetrahydrofolate reductase (MTHFR) deficiency was diagnosed in a 1-month-old baby with signs of cerebral distress. Under a classic treatment using methionine supplementation, methyl donor (betaine) folinic acid, vitamin B(6) and vitamin B(12), the neuromotor development was satisfactory. At 15 years of age, however, despite no clear modification of the biochemical markers in body fluids, she developed a clinically overt peripheral axonal neuropathy. Only partial clinical improvement was obtained after reinforcement of betaine doses. Surveillance of the peripheral nerve is indicated in MTHFR deficiency, including in the infantile form with a good therapeutic compliance.

F-waves: neurophysiology and clinical value.

This review deals with F responses, which are late responses obtained by supramaximal stimulation of virtually all the motor and mixed peripheral nerves. They are recorded over a muscle innervated by the stimulated nerve. The first description of F-waves was published in the fifties. Their neurophysiological mechanisms have been abundantly discussed in the literature leading to a current consensus, whereby F-waves are considered as antidromic responses produced by a pool of motoneurons activated by peripheral nerve stimulation. In the first part of this review, the neurophysiological mechanisms of F-waves as well as the distinction between these and H reflexes are described from a historical point of view. Other late responses are intentionally not reported; nevertheless A-waves are discussed since they are frequently ill-described in a number of conditions. Stimulation and recording procedures as well as F-wave parameters analysis are detailed, with emphasis on measures most useful for clinical purposes. A rigorous F-wave recording method is mandatory for reliable and meaningful analyses. Physiological factors, which influence F-waves such as ageing, drugs and sleep, must be known and their effects discussed. Also, as maturation is an important factor in clinical neurophysiology, data on F-wave ontogenesis are reviewed and discussed. Finally, the different F-wave alterations described so far in the literature, in either peripheral or central disorders, are listed and commented. It is emphasised that F-waves are particularly useful for the diagnosis of polyneuropathies at a very early stage and for the diagnosis of proximal nerve lesions. F-wave recording is indeed one of the rare methods in routine examination allowing at the same time the functional assessment of motor fibres on their proximal segment, and contributing to the evaluation of motoneuronal excitability.

Phase II trial of thalidomide in renal-cell carcinoma.

BACKGROUND: Thalidomide has been reported to yield anti-tumor activity in cancer. We performed a phase II trial of this drug in patients with metastatic renal cell carcinoma to determine its efficacy. PATIENTS AND METHODS: Patients with proven metastatic renal cell cancer, measurable progressive disease and a performance status of 0-2 were enrolled in this study. Thalidomide was given daily at a starting dose of 400 mg, followed by a 400 mg increment to 800 mg and then to 1200 mg with 6-12 weeks at each dose level. The response rate at 6 months was the primary end point. Toxicity, overall survival, tumor vascularization depicted on color Doppler ultrasonography and serum vascular endothelial growth factor, basic fibroblast growth factor, interleukin-12 and tumor necrosis factor-alpha levels were secondary end points. RESULTS: Forty patients were enrolled. Two partial responses were observed (5%) and disease remained stable in nine patients after 6 months. Median survival was 10 months. Toxicity was high, with frequent manifestations of fatigue, constipation and lethargy. The incidence of neuropathy detected on electromyography (EMG) attained 70% at 6 months, and 100% in patients on thalidomide for 12 months. Nine patients developed venous thromboembolism during the first 12 weeks of treatment, and three of them experienced pulmonary embolism. One unexpected (and unexplained) death occurred. CONCLUSIONS: Despite undisputed, albeit marginal, activity in renal cell cancer, high-dose thalidomide cannot be recommended using this schedule since the level of toxicity is high.