Electrophysiological features of familial amyloid polyneuropathy in endemic area

The process of deterioration of peripheral nerve function in familial amyloid polyneuropathy (FAP) with amyloidogenic transthyretin (ATTR) Val30Met has not been systematically evaluated hitherto. We performed nerve conduction studies in 69 patients with FAP with ATTR Val30Met from one of the endemic areas in Japan. Sensory conduction velocity (SCV), motor conduction velocity (MCV), the size of the compound muscle action potential (CMAP) and distal latency (DL) were measured in the ulnar and tibial nerves. SCV was evaluated using the orthodromic method with needle recording electrodes. These electrophysiological parameters were compared with clinical stage of FAP and duration of neuropathy. When subjects noted minimal neuropathic symptoms only in the feet, motor and sensory nerve function in both the hands and feet had already been disturbed. Sensory nerve action potential on the foot disappeared more rapidly than CMAP. CMAP on foot muscle rapidly decreased during the initial 2 years and completely disappeared within 10 years. The duration of illness and deterioration parameters (CMAP of the abductor digiti minimi muscle, MCV and SCV of the ulnar nerve and DL of both ulnar and tibial nerves) were linearly correlated. CMAP was the most sensitive and reliable parameter to evaluate motor nerve degeneration in FAP.</.ArticleAMYLOID-JOURNAL OF PROTEIN FOLDING DISORDERS. 18(1):10-18 (2011)journal articl

The safety of transcranial magnetic stimulation with deep brain stimulation instruments

Objectives: Transcranial magnetic stimulation (TMS) has been employed in patients with an implanted deep brain Stimulation (DBS) device. We investigated the safety of TMS using Simulation models with an implanted DBS device. Methods: The DBS lead was inserted into plastic phantoms filled with dilute gelatin showing impedance similar to that of human brain. TMS was performed with three different types of magnetic coil. During TMS (I) electrode movement, (2) temperature change around the lead, and (3) TMS-induced current in various Situations were observed. The amplitude and area of each evoked current were measured to calculate charge density of the evoked current. Results: There was no movement or temperature increase during 0.2 Hz repetitive TMS with 100% stimulus intensity for 1 h. The size of evoked current linearly increased with TMS intensity. The maximum charge density exceeded the safety limit of 30 mu C/cm(2)/phase during Stimulation above the loops of the lead with intensity over 50% using a figure-eight coil. Conclusions: Strong TMS on the looped DBS leads should not be administered to avoid electrical tissue injury. Subcutaneous lead position should be paid enough attention for forthcoming Situations during surgery.ArticlePARKINSONISM & RELATED DISORDERS. 16(2):127-131 (2010)journal articl

Electrophysiological features of familial amyloid polyneuropathy in endemic area

The process of deterioration of peripheral nerve function in familial amyloid polyneuropathy (FAP) with amyloidogenic transthyretin (ATTR) Val30Met has not been systematically evaluated hitherto. We performed nerve conduction studies in 69 patients with FAP with ATTR Val30Met from one of the endemic areas in Japan. Sensory conduction velocity (SCV), motor conduction velocity (MCV), the size of the compound muscle action potential (CMAP) and distal latency (DL) were measured in the ulnar and tibial nerves. SCV was evaluated using the orthodromic method with needle recording electrodes. These electrophysiological parameters were compared with clinical stage of FAP and duration of neuropathy. When subjects noted minimal neuropathic symptoms only in the feet, motor and sensory nerve function in both the hands and feet had already been disturbed. Sensory nerve action potential on the foot disappeared more rapidly than CMAP. CMAP on foot muscle rapidly decreased during the initial 2 years and completely disappeared within 10 years. The duration of illness and deterioration parameters (CMAP of the abductor digiti minimi muscle, MCV and SCV of the ulnar nerve and DL of both ulnar and tibial nerves) were linearly correlated. CMAP was the most sensitive and reliable parameter to evaluate motor nerve degeneration in FAP.</.ArticleAMYLOID-JOURNAL OF PROTEIN FOLDING DISORDERS. 18(1):10-18 (2011)journal articl

Analysis of Distal Compound Muscle Action Potential Duration in Hereditary Transthyretin Amyloidosis with Polyneuropathy

Background : Hereditary transthyretin (ATTRv) amyloidosis, a disorder accompanied by axonal polyneuropathy, is often misdiagnosed as chronic inflammatory demyelinating polyneuropathy (CIDP). Prolongation of distally evoked compound muscle action potential duration (DCMAPD), an electrophysiological parameter of heterogeneous conduction delay at the distal part of the motor nerve suggesting demyelinating neuropathies, is included in an index of diagnostic criteria for CIDP. However, DCMAPDs are strongly influenced by low-frequency filtering (LFF) settings, which differ across hospitals worldwide. Aim : To analyze DCMAPD in patients with ATTRv amyloidosis with polyneuropathy (ATTRv-PN). Methods : DCMAPs of the median, ulnar, tibial, and peroneal nerves were recorded under LFF settings of 2, 10, and 20 Hz in 50 patients with ATTRv-PN. The changes of DCMAPD accompanied with the changes of LFF settings were analyzed. The appropriateness of the cut-off values of the DCMAPD in the latest criteria for CIDP, which defined under various LFF settings, was also validated in ATTRv-PN patients. Results : The DCMAPD was shorter with increasing LFF settings. Less than 10 ％ of patients with ATTRv-PN demonstrated prolonged DCMAPD of the ulnar, tibial, and peroneal nerves. In contrast, ten patients demonstrated prolonged DCMAPD in the median nerve under LFF settings of 2, 10, and/or 20 Hz. Nine of the ten cases were complicated with carpal tunnel syndrome (CTS). Conclusion : Prolongation of DCMAPDs in the ulnar, tibial, and peroneal nerves is rare in ATTRv-PN patients. DCMAPD analysis of the median nerve in patients with ATTRv-PN requires caution, because they frequently develop CTS and those with CTS may demonstrate prolonged DCMAPD.Article信州医学雑誌 72(2) : 87-94, (2024)journal articl

Echoic memory: investigation of its temporal resolution by auditory offset cortical responses.

Previous studies showed that the amplitude and latency of the auditory offset cortical response depended on the history of the sound, which implicated the involvement of echoic memory in shaping a response. When a brief sound was repeated, the latency of the offset response depended precisely on the frequency of the repeat, indicating that the brain recognized the timing of the offset by using information on the repeat frequency stored in memory. In the present study, we investigated the temporal resolution of sensory storage by measuring auditory offset responses with magnetoencephalography (MEG). The offset of a train of clicks for 1 s elicited a clear magnetic response at approximately 60 ms (Off-P50m). The latency of Off-P50m depended on the inter-stimulus interval (ISI) of the click train, which was the longest at 40 ms (25 Hz) and became shorter with shorter ISIs (2.5∼20 ms). The correlation coefficient r2 for the peak latency and ISI was as high as 0.99, which suggested that sensory storage for the stimulation frequency accurately determined the Off-P50m latency. Statistical analysis revealed that the latency of all pairs, except for that between 200 and 400 Hz, was significantly different, indicating the very high temporal resolution of sensory storage at approximately 5 ms

Anterior horn damage in brachial multisegmental amyotrophy with superficial siderosis and dural tear: an autopsy case report

Abstract Background Patients with superficial siderosis (SS) rarely show brachial multisegmental amyotrophy with ventral intraspinal fluid collection accompanied with dural tear. Case presentation We describe spinal cord pathology of a 58-year-old man who developed brachial multisegmental amyotrophy with ventral intraspinal fluid collection from the cervical to lumbar spinal levels accompanied with SS, dural tear, and snake-eyes appearance on magnetic resonance imaging (MRI). Radiological and pathological analyses detected diffuse and prominent superficial deposition of hemosiderin in the central nervous system. Snake-eyes appearance on MRI expanded from the C3 to C7 spinal levels without apparent cervical canal stenosis. Pathologically, severe neuronal loss at both anterior horns and intermediate zone was expanded from the upper cervical (C3) to middle thoracic (Th5) spinal gray matter, and these findings were similar to compressive myelopathy. Conclusion Extensive damage of the anterior horns in our patient may be due to dynamic compression induced by ventral intraspinal fluid collection

Relationship between the Off-P50m latency and stimulus frequency.

<p>(A) The Off-P50m latency as a function of the ISI of the click train. The right column shows the latency difference of Off-P50m for each click sound relative to that for the 25-Hz train. Dotted lines indicate theoretical values. (B) Schematic illustration of the relationship between the latency of Off-P50m and ISI. Note that the delay in P50m latency reflects the click interval and the difference calculated by subtracting ISI from the P50m latency for each click is constant (right column).</p