Over the past decade, diffusion tensor imaging (DTI) has offered researchers and clinicians a new noninvasive window into the human brain. DTI infers the trajectory and location of large white matter tracts by measuring anisotropic diffusion of water. DTI data may then be analyzed and presented as fractional anisotropy (FA) mapping, vector map, Ellipsoid image, and 3D fiber tractography. Three-dimensional fiber tractography based on DTI is useful for neurosurgical planning, and stereotactic radiotherapy, which present relationship between tumor and white matter tracts. Furthermore, several studies have suggested disorganization of the specific tract in Alzheimer disease, schizophrenia,and amyotrophic lateral sclerosis, etc. In this article, first,we briefly explain the basic physics of diffusion-weighted imaging (DWI) and DTI, and then present some clinical applications.
Measurement of multichannel continuous-wave near-infrared spectroscopy (CW-NIRS) is dependent on the modified Beer-Lambert law, which includes optical path length (PL) as an essential parameter. PLs are known to differ across different head regions and between individuals, but the distribution of PLs for the whole head has not been evaluated so far. Thus, using time-resolved near-infrared spectroscopy (TR-NIRS), we measured the optical characteristics, including PL, scattering coefficients (μls), and absorption coefficients (μa) at three wavelengths (760, 800, and 830 nm). We then constructed maps of these parameters on the surface of the subject′s head. While the PLs in nearby channels are similar, they differ depending on the regions of the head. The PLs in the region above the Sylvian fissure tended to be shorter than those in the other regions at all of the wavelengths. The difference in the distribution of PLs may be attributed to differences in tissue absorption and scattering properties. The current study suggests the importance of considering PL differences in interpreting functional data obtained by CW-NIRS.
Archeological evidence from ancient Chinese and Mesopotamian civilizations has shown that humans have been drinking alcohol for several thousand years. Alcohol is consumed for various reasons, including recovery from daily fatigue, alleviation of psychological stress, and promotion of smooth personal relationships, and its effects may indeed be remarkable. However, excessive consumption of alcohol (60 g/day<) results in damage to various organs. Examples of diseases involving by damage to the nervous system include polyneuritis, cerebellar degeneration, alcoholic dementia, pellagra encephalopathy, Marchiafava-Bignami and Wernicke-Korsakoff syndrome. Alcohol consumption influences the fluidity of the membrane of nerve cells and changes the composition of these membranes. Alcohol and acetaldehyde in the brain influences the appearance of receptors involved in metabolizing neurotransmitter, synthesis of neurotransmitters and modulation of the functions. It is estimated that there are sixty to sixty-five million people who drink alcohol in Japan. It is speculated that 12-13% of men and 3-4% of women in the Japanese population are heavy drinkers. About half of Japanese lack ALDH2 (aldehyde dehydrogenase 2), an enzyme involved in alcohol metabolism. Therefore, it is speculated that the Japanese people are easily influenced by excessive alcohol drinking. As indicated above, consumption of alcohol causes many neurologic diseases, and some of these diseases need to be diagnosed and treated at an early stage, especially Wernicke-Korsakoff syndrome, Marchiafava-Bignami and pellagra, because delays in treatment may be fatal. It is important for heavy alcohol drinkers stop drinking or at least drink moderately.
Origin of night dream has been an enigma through whole history of human race. Descriptions in the Bible have shown that the ancients regarded dream experiences as a consequence of the supernatural power outside. Since the early twentieth century, progresses of psychology have proposed that night dream comes from the unconscious mind inside. Finally in 1953, Aserinsky and Kleiteman discovered human REM sleep and demonstrated that dream reports were obtained most frequently when subjects were awakened from REM sleep. Thereafter, many scientists conducted studies on dream and REM sleep, and found a robust association between electrophysiologic phenomena and subjective experiences during REM sleep. Here we reviewed articles on psychophysiological aspects of dream and REM sleep. To document mnemonic functions of REM sleep was of our particular interest. The authors expect that studying dream and REM sleep gives clues to an understanding on the mind-body relationship.
Deep brain stimulation (DBS) is an important component of the therapy for movement disorders and intractable pain. In Japan, the first case of DBS for controlling central pain syndrome was experienced in 1979 and DBS of the thalamic nucleus ventralis caudalis and periaqueductal gray matter have been used for pain control for many years. Neurosurgeons also initiated a clinical trial of DBS for controlling movement disorders, such as tremor, Parkinson′s disease (PD) and dystonia. Our government approved DBS to be covered by the public insurance system for pain control in 1992 and for movement disorders in 2000. In particular, DBS for subthalamic nucleus (STN) is currently the most common therapeutic surgical procedure for patients with PD. The long-lasting beneficial effects of STN-DBS on motor function have now largely been acknowledged. However, behavioral and/or psychiatric changes have been demonstrated in certain case reports and case series. DBS is also a successful therapeutic option for patients with primary dystonia and tremor syndrome who do not respond sufficiently to conservative therapies. The most common target of DBS in patients with dystonia is the internal region of the globus pallidus (GPi). GPi-DBS leads to long-lasting and remarkable improvement of dystonic movements in majority of patients. In Parkinson′s tremor or post-stroke movement disorder, the intermediate ventral nucleus of the thalamus (Vim) and the subthalamic region have proven to be promising targets for DBS electrodes. Especially in patients with essential tremor, Vim-DBS leads to an acute reduction of the tremor. In addition, DBS is beginning to be used as a new therapeutic procedure for psychiatric diseases, such as depression and obsessive-compulsive neurosis in many countries. We will summarize our experiences and previous reports, and discuss the mechanism and future perspectives for DBS in the management of central nervous system disorders.
Neuropathic pain is characterized by partial or complete somatosensory changes in the innervation territory corresponding to peripheral or central nervous system pathology, and the paradoxical occurrence of pain and hypersensitivity phenomenon within the denervated area and its surroundings. In clinical practice, electrical pain and allodynia are the most important findings in the diagnosis of typical neuropathic pain. The best way to relive neuropathic pain is considered to be pharmacologic treatment, except for NSAIDs. Evidence-based clinical recommendations for pharmacotherapy are required. Recommended first-line treatments include certain antidepressants (tricyclic antidepressant) and antiepileptics (gabapentin and pregabalin). Opioid analgesics are generally recommended as a second-line treatment. To reduce the number of patients who suffer from neuropathic pain, the primary care physician should be familiar with neuropathic pain and prescribe adequate medications based on recommended first-line treatments. Therefore the pain clinician should provide information to the primary care physician regarding what is neuropathic pain, how to diagnose it, how to assess spontaneous pain intensity and characteristics, how to examine sensory disturbance, how to prescribe antidepressants and antiepileptics, how to pay attention to potential side effects, and how to decide when to refer to a pain clinic.
Event-related potentials reflect various cognitive functions and include the mismatch negativity and P300. The mismatch negativity is said to reflect the process in which stimuli are detected automatically. The mismatch negativity requires no concentration of attention or understanding of the subject, and is useful for objectively evaluating the cognitive ability in newborns. The P300 wave is generally interpreted as a neural correlate of decision-making or of signal detection by an actively attentive subject. Studies of event related potentials in children, based on a task relevant oddball paradigm, reveal a decrease in the latency of P300 with increasing age. This developmental change could be related to maturation phenomena in cognitive processes. Squires et al. delineated P3a and P3b components in P300. In our study, P300 in a state of ignoring, likely corresponds to P3a (passive attention), whereas conventional P300 corresponds to P3b (active attention). These findings indicate a developmental difference between the P3a and P3b potentials. The development of fundamental cognitive function like passive attention reaches the adult level at an earlier age than the cognitive-like active attention. To evaluate auditory spatial cognitive function, age correlations for event-related potentials in response to auditory stimuli with a Doppler effect were studied in normal children. From the age of 4 years, the P300 latency for the enlarged tone with a Doppler effect shortened more rapidly with age than did the P300 latency for tone-pips, and the latencies for the different conditions became similar towards the late teens. These findings provide evidence that auditory cognitive function, including auditory spatial cognitive function, had reached the adult level by about this age. P300 in response to different stimuli may provide more detailed information that could enable the evaluation of cognitive function development in children.
Blood pressure (BP) measured in medical environments can vary according to the location of measurement, as well as the medical professional conducting the measurement. This variation is associated with sympathetic hyperactivity that follows psychological stress. However, psychological stress or sympathetic activities are difficult to assess. It has recently been reported that salivary chromogranin A (CgA) is a useful marker of psychological stress. In this study, we investigated the significance of salivary CgA in BP variation induced by a change in medical professionals measuring the BP (physician and nurse), in individuals undergoing a health check-up. Salivary CgA was measured in 126 individuals at rest, during BP measurement by a nurse, and during BP measurement by a physician. In summary, the BP was 140/90 mmHg or higher in 14% of the subjects only when measured by the physician. When BP was increased, the salivary CgA level sampled during BP measurement also increased significantly. Thus, because variation in BP at a health check-up is associated with psychological stress or sympathetic hyperactivity induced by BP measurement by a physician, salivary CgA level may be a useful objective marker of stress or hyperactivity. Hence, we consider that salivary CgA may be clinically useful in assessing “white-coat phenomenon”.
Papillary muscle rupture is considered to be one of the least frequently observed complications of acute myocardial infarction (AMI) and has a significantly high mortality. We report a case of a patient who survived due to an emergency surgery for papillary muscle rupture after AMI with cardiogenic shock. A 64-year-old male patient was emergently admitted with chest pain as the chief complaint. He was diagnosed with papillary muscle rupture after AMI by electrocardiography, cardiac catheterization, and echocardiography. Since he had gone into cardiogenic shock during cardiac catheterization, he received assisted circulation with intraaortic balloon pumping and emergent mitral valve replacement. Complete rupture of the posterior papillary muscle and severe mitral regurgitation were observed intraoperatively. The postoperative condition was favorable with no complication and the patient was discharged 12 days after the operation.