P4.25 Plantar digital nerves anatomic variation and occurrence of neurinomas in cadavers

14th ECCN / 4th ICTMS/DCS left or to right monitor’s side (LeSi RiSi) and with two time delay (TD 70 and 130 ms). Eight healthy subjects were performed 10 consecutive sessions of pointing movements lasting a total time of 60 s per session. Target was presented with a frequency between 3 to 5 s. Time stamps of relevant events as fingertip reaction time to target onset (RT), finger correction initiation and eyes saccade termination times with respect to target perturbation onset (CT and Sac_T), peak-EMG time delay to target perturbation were calculated by means of 3-D kinematics, surface EMG for flexor and extensor muscles and electroculogram. Results: (1) Mean RT decreased during the sessions (290 to 214 ms for LeSi, 300 to 247 ms for RiSi, 276 to 234 ms for central position) in both TD conditions. (2) Main variations of time delay of peak EMG to target perturbation onset for extensor digiti (EXD) and tricpes brachii (TRI) were significant during the sessions. For EXD from 95 to 156 ms and from 139 to 123 ms; for TRI from 209 to 39 ms and from 160 to 57 ms for LeSi and RiSi target perturbation respectively. (3) During sessions with TD 130 ms, mean values of CT and Sac_T were 120 ms and 210 ms respectively. CT was lower for RiSi than for LeSi target perturbation 114 ms vs 133 ms. Conclusions: There is evidence that initiation of movement correction does not need information based at the end of saccade but could related to visual information coming from the peripheral field occurring without any processing from higher CNS centers (V1 occipital areas). P4.24 A test for longitudinal sliding of the ulnar nerve at the elbow A. Jaen1 , J. Valls-Soler1 , A. Selvi1 1 Department of Neurology, Hospital Clínic de Barcelona, Barcelona, Spain Introduction: Longitudinal sliding is a physical property of peripheral nerves. In the upper limb, the ulnar nerve lengthens and the median nerve shortens with elbow flexion. Longitudinal sliding of the ulnar nerve at the elbow may be measured as peak latency displacement of the mixed nerve action potentials (mNAP) recorded in extreme flexion and extension. Objectives: To examine the changes in longitudinal sliding in ulnar nerve lesions at the elbow. Methods: In 10 patients with unilateral ulnar nerve entrapment, we stimulated the median and ulnar nerves simultaneously at the wrist, using a surface bar electrode, and recorded the mNAP from both nerves simultaneously at the medial upper arm (5 cm distal to the axilla). The intensity of the stimulus was adjusted to produce a clear muscle twitch in ulnar and median nerve innervated hand muscles and stimulation-induced paresthesias in both nerve territories. We first recorded the mNAP in elbow extension (180º) and then in elbow flexion (30º). The same test was done in a group of 10 healthy volunteers. Results: In healthy subjects, the mNAP in 180º was composed by a single peak, which transformed to two peaks in the 30º position. The first peak, generated by the median nerve, was of reduced latency, and the second one, generated by the ulnar nerve, was of increased latency, with respect to the single peak obtained in the extended position. The mean interpeaklatency was 0.95 ms (SD = 0.1 ms). Patients showed either the absence of the second peak or had an abnormally reduced mean interpeak latency. When present, the second peak in the flexed position did not show a latency shift. Conclusions: The lack of latency shift of the ulnar nerve mNAP recorded al the axilla when changing the arm position from extension to flexion indicates reduced nerve longitudinal sliding and may be an expression of physical entrapment. The manoeuvre may be added to electrophysiological tests to characterize focal peripheral nerve lesions. P4.25 Plantar digital nerves anatomic variation and occurrence of neurinomas in cadavers S. Laaksonen1 , K. Nyrhinen2 , B. Falck3 1 Department of Clinical neurophysiology, Turku, Finland, 2 Department of Clinical Neurophysiology, Turku, Finland, 3 Uppsala University Hospital, Uppsala, Sweden Introduction: Plantar digital nerve lesions are common, particularly in women entrapment neuropathies between the metatarsal heads are seen. Lesions of these nerves can readily be diagnosed with neurography. Objectives: To study anatomic variation of plantar digital nerves and occurrence of neurinomas in cadavers. Methods: Feet of 36 cadavers (60 95 years) were studied, both feet were dissected in all but one. Digital plantar nerves were carefully dissected,

S77 photographed or drawn. If the digital plantar nerve was thicker distally than proximally, the site was suspected of neurinoma. All suspected neurinomas were confirmed histologically. Results: Plantar digital nerves had three anatomic variations. (1) absence of proper digital nerve on one side of the toe, (2) double innervation of to the toe next to the toe with absence of innervations from the proper nerve and (3) proper digital nerves innervating both toes and the other toe having two branches. 10 cadavers had neurinomas, 6 female and 4 men, mean age 79. 82 % of the neurinomas were on the left side. The most common site of neurinoma was 3 4 interspace. Hallux valgus was seen in 12 of feet, bilateral in 3. One female had hallux valgus and neurinoma in the same foot. Conclusions: There are significalt anatomical variations in the plantar digital nerves that must be taken into consideration when neuorgraphy is used to diagnose entrapment neuropathies between metatarsal heads. Plantar digital nerves have 3 types of anatomic variations. For accurate diagnosis of entrapment neuropathies both medial and lateral plantar digital nerves should be studied. Neurinomas were most common in females, the most common site for neurinoma was between 3 4 metatarsals. Unfortunately we do not know if these were symptomatic or not. There was no correlation between bony alterations and the occurence of neurinomas.

Poster session 5. EMG, nerve conduction, peripheral neuropathies 2 P5.1 Nerve conduction study of intercostal nerve by magnetic stimulation. Case report L. Ruiz1 , R. Chilet1 , M. Escudero1 , P. Giner1 , A. Mazzillo1 , J. Moliner1 , A. Rodrigo1 , N. Torres1 , G. Zalve1 1 Department of Clinical Neurophysiology H. Dr. Peset, Valencia, Spain The innervations of the abdominal wall is derived from the intercostals nerves T 7 to T 12. The autonomic nervous system provides visceral pain afferent fibers through the sympathetic system. The most common causes of abdominal pain of visceral or parietal origin include surgical incisions, nerve entrapment syndromes, abdominal hernias, myofascial syndromes, syndrome “rib slider”, disorders spinal or paraspinal hematoma of rectus muscle, and idiopathic. Case report: 55 year old man without medical antecedents of interest. Refer previous trauma on right costal region, after it has pain in right abdomen. Following 2 month of injury presents deformity right abdomen. The neurological examination was normal, chest x-ray imaging tests are not rib fracture lines. EMG is performed using needle electrodes to examine the abdominal rectus superior and inferior, showing significant impairment of acute denervation in the form of positive waves and fibrillation, as well as potential highly polyfasic motor unit. To complete the study was performed a nerve conduction study using magnetic stimulation. The recording electrodes were placed over the cranial part of the rectus abdominal muscle. Stimulation was performed paravertebrally, and at a distance of 10 cm between stimulating and recording electrodes. The results were compatible with intercostals nerve neuropathy axonotmesis partial degree. Magnetic stimulation is a painless technique and easy to realize that could represent useful in this type of pathology. P5.2 Diagnosis of early myelin involvement in diabetes as first sign of polyneuropathy: single fiber conduction velocity test alberg3 , P. Caliandro1,2 , G. Muscogiuri4 , C. Pazzaglia1,2 , L. Padua1,2 , E. St˚ G.P. Sorice4 , G. Granata1,2 , E. Salomone4 , A. Pontecorvi4 , A. Giaccari4 1 Department of Neuroscience, Institute of Neurology, Catholic University, Rome, Italy, 2 Don Carlo Gnocchi Onlus Foundation, IRCCS, Italy, 3 Department of Clinical Neurophysiology, Uppsala University Hospital, Uppsala, Sweden, 4 Division of Endocrinology, Catholic University, Rome, Italy Introduction: The identification of Diabetic polyneuropathy (DP) at its earliest stages is a major challenge in the clinical care of diabetes. Conventional conduction velocity, through surface electrodes (C-CV) does not optimally assess the overall conduction properties of a nerve, because it mainly reflects the fastest-conducting subset of the alpha motor axon population.[3] Single Fiber CV (SF-CV) evaluation is a technique based on