Baris Isak

Involvement of distal sensory nerves in amyotrophic lateral sclerosis

The diagnostic criteria for amyotrophic lateral sclerosis (ALS) require normal sensory nerve conduction studies (NCS) or abnormal NCS only in the presence of neuropathy of identified etiology. In this study, we investigated the presence and extent of involvement of Aß sensory fibers in ALS.

Quantitative sensory testing and structural assessment of sensory nerve fibres in amyotrophic lateral sclerosis

OBJECTIVE In this prospective study, involvement of sensory nerve fibres in ALS patients was assessed using functional and structural measures in the form of quantitative sensory testing (QST) and skin and nerve biopsies. METHODS Thirty-two ALS patients and 32 healthy subjects were evaluated with a QST battery comprising thresholds of mechanical detection, mechanical pain, vibration detection, cold detection, warm detection, heat pain, and pinprick sensation. Skin biopsies were evaluated in 31 ALS patients by intraepidermal nerve fibre density (IENFD) and axonal swelling ratios, and growth-associated protein 43 (GAP-43) antibody staining. Sural nerve biopsies were evaluated using teased fibre analysis in eight patients. RESULTS Mean values for QST parameters and IENFD in ALS patients were within normal range. However, the patients had increased axonal swelling ratios and GAP-43 antibody staining was negative in all patients. CONCLUSIONS Although QST and IENFD were affected in only a small subset of ALS patients, the axonal swellings observed in all patients indicate that the affection is more frequent, and suggests that IENFD count may not be sufficient. The negative GAP-43 staining suggested an insufficiency of regeneration in small sensory nerve fibres.

Chronic Pain and Neuropathy Following Adjuvant Chemotherapy

Objective To determine symptoms and characteristics of chronic sensory neuropathy in patients treated with oxaliplatin and docetaxel, including patterns of somatosensory abnormalities, pain descriptors, and psychological functioning. Design A retrospective cross-sectional study. Setting A chronic pain research center. Subjects Thirty-eight patients with chronic peripheral pain and/or dysesthesia following chemotherapy. Methods Sensory profiles, psychological functioning, and quality of life were assessed using standardized questionnaires. In addition, standardized quantitative sensory testing and nerve conduction studies were carried out. Results The sensory profiles and clinical symptoms were very similar in the two groups. Pricking, numbness, and burning were common descriptors in both groups, and the predominant finding was sensory loss to A beta-mediated sensory modalities with decreased mechanical and vibration detection thresholds. A high frequency of abnormalities in thermal sensory limen and the presence of paradoxical heat sensation seem to be sensitive markers of small fiber loss. Both groups had mainly sensory, axonal large fiber or mixed fiber polyneuropathy, which tended to be most severe in the oxaliplatin group. Conclusions Both oxaliplatin-induced and docetaxel-induced polyneuropathies represent a significant problem that affects the daily life of the patients. Our results, defining the somatosensory phenotype, can improve the understanding of the pathophysiological mechanisms useful for future studies in the tailored treatment of prevention of chemotherapy-induced peripheral neuropathy and pain.

O6 The utility of distal nerve conduction studies and sural near-nerve needle recording in electrodiagnosis of polyneuropathy

Objectives To compare the diagnostic utilities of distal surface electrode recording of dorsal sural and medial plantar nerves and near-nerve technique (NNT) and conventional surface recording of sural nerve. Methods Ninety-one patients referred for electrodiagnostic examination of polyneuropathy (PNP) were included. Bilateral nerve conduction studies (NCS) of the sural nerve with NNT and surface recording, and of the distal nerves with surface recording were done in all patients. Results were compared to 37 age-matched healthy subjects. The final clinical diagnosis retrieved from the patients’ medical records as diagnostic reference standard showed PNP in 68 patients (PNP+) and 20 patients did not have PNP (PNP−). Results The sensitivities of the dorsal sural (68%) and medial plantar (70%) nerves were similar to that of NNT recording of the sural nerve (74%), while the sensitivity of surface recording of the sural nerve was lower (55%). High specificities (93–98%) were seen for sural NCS with both NNT and surface recording and for the dorsal sural nerve, while the specificity for medial plantar nerve was low (76%). Discussion In concert with previous reports, distal nerves have higher sensitivity than conventional sural nerve. Additionally, the sensitivity of distal nerves was found to be similar to examination of sural nerve with NNT. Conclusion NCS of the distal nerves, especially the dorsal sural nerve, have a high diagnostic power at an identical level of that of needle recording of the sural nerve. Significance Examination of distal nerves.should be included into routine electrodiagnostic evaluation of patients with suspected PNP.

Diagnostic utility of distal nerve conduction studies and sural near-nerve needle recording in polyneuropathy

OBJECTIVE The electrodiagnosis of polyneuropathy (PNP) may benefit from examination using near-nerve needle technique (NNT) and from inclusion of distal nerves. This study compared the diagnostic utility of distal nerve conduction studies (NCS) and NNT recording. METHODS Bilateral NNT and surface recording of the sural nerve and surface recording of the dorsal sural and medial plantar nerves were prospectively done in 91 patients with clinically suspected PNP. Distal NCS were additionally done in 37 healthy controls. Diagnostic reference standard was the final clinical diagnosis retrieved from the patients medical records after 1-4years. RESULTS The clinical follow-up diagnosis confirmed PNP in 68 patients. Equally high sensitivities of the dorsal sural (72%), medial plantar (75%), and sural nerve with NNT recording (77%) were seen, while the sensitivity of conventional surface recording of the sural nerve was lower (60%). Sural NCS with both NNT and surface recording and dorsal sural NCS showed high specificities (85-95%) and positive predictive values (94-98%), while a lower specificity was seen for the medial plantar nerve (68%). CONCLUSION NCS of distal nerves, especially the dorsal sural nerve, have high diagnostic power equalling sural NNT recording. SIGNIFICANCE The electrodiagnostic evaluation of patients with suspected PNP benefits from NCS of distal nerves.

P831: Laser evoked cutaneous silent periods in patients with chemotherapy induced polyneuropathy

Question: Short-term habituation (STH) is known as a fundamental component of attention since it represents a cortical “bottom-up” filter for salient stimuli. Our aim was to verify if STH is still preserved in patients with different levels of Disorder of Consciousness (DOC), namely vegetative (VS) versus minimally conscious state (MCS). Methods: We selected 40 DOC patients assessed with a standardized neurobehavioral examination (Coma Recovery Scale-Revised). We performed a multimodal neurophysiological evaluation that included EEG, somatosensory evoked potentials, oddball protocol and STH paradigm. The STH protocol provides for the delivery of trains of three stimuli (S1-S2-S3): S1 and S2 always belongs to the same sensory modality (auditory or somatosensory) whereas S3 can belong either to the same modality or to the alternative modality. S1/S2/S3-related N1-P2 amplitudes were compared in order to detect any STH. Results: STH was detected in each emerging and MCS patient, whereas it was found absent only in the VS group (10 out of 19): until now, none of these 10 patients has regained consciousness. Among the 9 VS patients showing STH, 4 have subsequently become MCS. Conclusions: STH could represent a new potential diagnostic/prognostic neurophysiological tool in DOC. The STH protocol may be able to pick-up preserved elementary information processing in DOC patients since we found a STH in every patient with a preserved level of consciousness (emerging and MCS groups). It remains to be determined whether the presence/absence of STH in an early DOC stage can have a prognostic value and whether the absence of STH in chronic VS can assume the significance of a diagnostic confirmation.