We conducted a postal questionnaire survey among 36 universities or research institutes possessing equipments for magnetoencephalograph (MEG) in Japan in May 2009. The main outcome measures were answers to questions on detailed clinical information about patients referred to MEG testing and the protocols of recording and analyzing the MEG. Questions also were posed about current status and problems in clinical applications of the MEG, including any technical or financial problems doctors or medical technologists in charge of MEG examinations were facing at each facility.
Twenty four institutions responded to the questionnaire (response rate 67%). Annually 150 to 200 patients were referred to MEG testing in most institutes; but, in some institutes, the annual number of MEG examinations did not reach 50. Among clinical diagnoses of patients referred to MEG testing, epilepsy and brain tumors occupied about 50%, followed by dementia, cerebrovascular stroke and neurodegenerative disease. The ages of the patients were widely distributed; elderly patients over 60 years old reached about 16%.
Neurosurgeons and psychiatrists mainly assumed the responsibility for analyzing MEG results and for operating MEG machine. No laboratory medical technologists were posted in half of the institutions surveyed. The protocols of recording MEG consisted of spontaneous cerebral magnetic fields, somatosensory, auditory and visual evoked fields, movement-related magnetic fields and language dominancy analysis. The staffs in many institutes longed for a software package of automated epileptic spike detection when analyzing spontaneous cerebral magnetic fields in patients with epilepsy.
The annual running costs for MEG facilities ranged 5 to 20 million yen, resulting in a heavy debt in 83% of the institutions. Expanding clinical applications of MEG testing as well as increasing reimbursement from National Health Insurance are needed to reduce the debt in future.

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The concept of thoracic outlet syndrome (TOS) has been a subject of much controversy in USA. Professor Wilbourn argued that the rare true neurogenic TOS (TNTOS) presenting with the thenar atrophy is the only established disorder, and the other majority of patients who had been diagnosed as TOS, complaining various head, neck and arm symptoms without documented neurophysiological abnormalities, should be designated as disputed neurogenic TOS (DNTOS). Such a controversy has not been popularly known in Japan, and there have been few case reports of TNTOS patients, especially with detailed neuropysiological investigations.
In this study, we report clinical and electrodiagnostic features of 4 patients with TNTOS who were experienced at our institute for 12 years, and also presented the clinical features of 7 patients who were referred to the first author under the diagnosis of TOS from other doctors. Presenting symptoms of all four TNTOS patients were thenar atrophy or other motor symptoms. Two patients noticed mild sensory symptoms in the medial aspect of the forearm. Neurological examinations revealed the weakness of abductor pollicis brevis (APB), and ulnar-innervated small hand muscles to a lesser extent. The flexor digitorum profundus (FDP) muscle to the index finger was weak, but that to the little finger was preserved for all patients. All patients had objective sensory loss in the medial aspect of the forearm. Motor nerve conduction studies revealed severe decrease of the amplitude of the compound muscle action potential (CMAP) from the APB muscle and mild decrease of the CMAP from the abductor digiti minimi muscle for all patients. Sensory nerve conduction studies documented loss or severe depression of the sensory nerve action potential (SNAP) from the medial antebrachial cutaneous (MAC) nerve and moderate decrease of the SNAP amplitude from the ulnar nerve and from the ring finger following the median nerve stimulation. Needle EMG, when examined, revealed greater involvement of the APB muscle than the first dorsal intereosseous muscle, and the C7-innervated muscles were normal. These electrophysiological results unequivocally indicated the lower trunk plexopathy that was dominant in the T1 components, which agrees with the localization documented for TNTOS by previous authors. The distribution of the weakness of present patients also revealed the T1 innervation of the median FDP muscles and the C8 innervation of the ulnar FDP muscles, which has not been reported previously. Among 7 other patients referred to the first author under the diagnosis of TOS, 5 showed evident hysterical weakness, and masked depression was evident in another patient. In this regard, these patients were thought to be classified under the category of DNTOS. The first author did not gave the final diagnosis of TOS to any other patient during the investigation period of 12 years. TNTOS is a rare disorder presenting with motor-dominant symptoms, and the electrodiagnosis clearly localizes the lesion at the T1-dominnant upper trunk for these patients. This concept should be strictly discriminated from the DNTOS, the presence of which is still controversial.

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Magnetoencephalography (MEG) was approved as an examination covered by health insurance in 2004, but the scientific evidence is not necessarily clear. In this study, we reviewed clinical MEG studies regarding epilepsy based on a website bibliographic survey. We searched epilepsy papers before July 2010 using MEDLINE by keywords: epilepsy AND (MEG OR magnetoencephalography OR (magnetic source imaging)). Nine hundred sixty-one papers were retrieved. We further narrowed the search to 65 papers based on levels of evidence and abstract contents. The levels of evidences were classified as grade 1: no paper, 2: 3 papers, 3: 20 papers, 4: 22 papers, 5: 14 papers, 6: 6 papers, respectively. Most of the papers reported clinical usefulness of MEG. Several papers certified the high levels of evidences that MEG is superior to scalp electroencephalography to estimate epileptic foci and to decide the placement site and area of intracranial electrodes. Although the present indication of health insurance for MEG is restricted to presurgical evaluation for the surgical cases, it should cover usefulness of the MEG evaluation for surgical indication.

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In this study, we examined 37 patients with brainstem vascular lesions. We found that brainstem auditory evoked potentials (BAEPs) are completely different in patients with acute rather than chronic vascular lesions in the pons. These data highlight the importance of BAEP follow-up studies and clarify the sites that generate these potentials. In this regard, the lesions limited wave V activity from the inferior colliculus to the rostral pons contralateral to the stimulated ear. On the other hand, the generation site of wave III activity depended on the decussating fibers of the trapezoid body. Moreover, a patient with a pontine hemorrhage clearly demonstrated that generation of wave III activity largely depended on the superior olivary complex contralateral to the stimulated ear. Similarly, wave IV ipsilateral stimulation to the lesion and wave V contralateral stimulation to the lesion were affected by the same discrete lesion at the mid portion of the pons, and the lesion anatomically included the nucleus of the lateral lemniscus. These data suggest that wave IVs are generated by the ipsilateral nucleus of the lateral lemniscus. The pathway of wave V activity likely crosses through Probst's commissure at the level of the mid-pons. We present a schematic illustration of the generation sites and pathways of BAEPs in humans. In this regard, wave I activity was generated by the VIIIth nerve, wave II activity was generated by the cochlear nucleus ipsilateral to the stimulated ear, wave III activity was generated by the superior olivary nucleus contralateral to the stimulated ear, wave IV activity was generated by the ipsilateral nucleus of the lateral lemniscus, and wave V activity was generated by the contralateral inferior colliculus. In addition, we describe the pathways for BAEP generation, the mechanisms that mediate binaural interactions, and the properties of the BAEP generators.

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