The vestibular system, essential for balance and spatial orientation, spans from the inner ear to various brain regions. Advances in imaging techniques have significantly enhanced our ability to diagnose and treat vestibular disorders. This review explores the anatomy of the vestibular system and evaluates the roles of high-resolution computed tomography (CT) and magnetic resonance imaging (MRI) in diagnosing structural abnormalities. CT is particularly useful for identifying bony labyrinth anomalies, temporal bone fractures, and superior canal dehiscence, though it has limitations in visualizing membranous labyrinth lesions. MRI, with its superior soft tissue resolution, is preferred for detecting retrocochlear lesions such as vestibular schwannomas, cerebellopontine angle tumors, and demyelinating diseases in the posterior fossa. Functional MRI also offers insights into the vestibular system’s functional aspects. The review emphasizes the increasing importance of imaging diagnostics in the effective management of vestibular system diseases, highlighting both structural and functional imaging modalities to improve patient outcomes.

Background
Myotonic dystrophy type 1 (DM1) is a multisystemic disorder caused by CTG repeat expansion in the DMPK gene. Brain involvement in DM1 has been reported, but quantitative imaging data is limited. This study aimed to characterize and quantify brain structural abnormalities in DM1 using MRI and DUIH-Image software.
Methods
Sixteen patients with classic DM1 (10 male, 6 female; age range 17–68 years) underwent genetic testing, neuropsychologic assessment, and brain MRI. FLAIR images were analyzed using DUIH-Image software to quantify brain lesions and create probabilistic lesion maps.
Results
FLAIR imaging revealed hyperintensities predominantly in periventricular and subcortical white matter. Probabilistic lesion maps highlighted the subcortical white matter near the anterior horn as the most affected site, with additional involvement of the posterior horn, frontal, insular, parietal, and temporal cortices. Neuropsychological testing identified frontal lobe dysfunction as the most common deficit, correlating with brain involvement. No significant correlations were found between lesion load, CTG repeat number, and disease duration.
Conclusions
This study demonstrates significant periventricular and subcortical white matter involvement in DM1, with the anterior subcortical white matter being the most affected site. Frontal lobe dysfunction was a frequent finding. Brain involvement did not correlate with CTG repeat number or disease duration, suggesting complex pathophysiology in DM1-related brain abnormalities.

Background
The brain magnetic resonance imaging (MRI) findings seen in patients with Bell's palsy are abnormal contrast enhancement of affected facial nerves. Previous evaluation included mainly patients who had experienced palsy for several weeks and there are no studies to date on patients with late stage of Bell’s palsy. This study investigated the findings of MRI of Bell's palsy after 3 months of symptom onset to assess how long the enhancement last.
Methods
Among the patients with Bell's palsy (idiopathic unilateral facial palsy) who visited the hospital, 9 patients who underwent contrast-enhanced MRI of the internal auditory canal after 3 months of symptom onset were reviewed retrospectively. MRI examination results were investigated along with the patient's clinical symptoms and electrodiagnostic test results. Based on the MRI results, the frequency of abnormal contrast enhancement and contrast-enhanced areas were investigated.
Results
9 patients were included. 6 of them did MRI imaging because of incomplete recovery of facial palsy and the others did because of complication of facial palsy including synkinesis and hemifacial spasm. Time interval between symptom onset and evaluation was 17 months (3-84). Of 9 patients, 2 showed abnormal enhancement of affected nerve and they performed MRI after 5 months and 12 months of symptom onset, respectively.
Conclusions
Abnormal enhancement of facial nerve in Bell’s palsy could last up to one year. This awareness can be helpful in interpretation of MRI of Bell’s palsy.

Iron is an important element for brain oxygen transport, myelination, DNA synthesis and neurotransmission. However, excessive iron can generate reactive oxygen species and contribute neurotoxicity. Although brain iron deposition is the natural process with normal aging, excessive iron accumulation is also observed in various neurological disorders such as neurodegeneration with brain iron accumulation, Parkinson’s disease, Alzheimer’s disease, multiple sclerosis, Friedreich ataxia, and others. Magnetic resonance image (MRI) is a useful method for detecting iron deposits in the brain. It can be a powerful tool for diagnosis and monitoring, while furthering our understanding of the role of iron in the pathophysiology of a disease. In this review, we will introduce the mechanism of iron toxicity and the basics of several iron-related MRI techniques. Also, we will summarize the previous results concerning the clinical application of such MR imagings in various neurological disorders.

Background
and Objective : Visual evoked potentials(VEPs) is considered to be a reliable diagnostic procedure for examining patients with anterior visual pathwyas. Some abnormalities in the recording on monocular stimulation have been said to indicate retrochiasmal lesion, but less consistent results have been reported. This study is to evaluate the positive predictability of VEP for the detection of retrochiasmal lesion. Methods : We reviewed VEPs that could be interpreted as indicative of a retrochiasmal lesions, based on amplitude or latency asymmetry recorded on the left(O1) and right(O2) occipital regions. Bilateral absent VEPs on both recording(O1 and O2) without evidence of prechiasmal lesions were included. During 5 years, we identified 31 patients who met the above criteria and who had undergone magnetic resonance imaging(MRI) of brain(one patient underwent computerized tomography). Twenty three patients underwent pattern reversal VEPs

Basic concept of functional magnetic resonance imaging(fMRI) is the detection of changing magnetic field during the activation of a neural network. The change of magnetic field depends on the hemoglobin oxidation-reduction ratio which corresponds to the degree of neural activation and following blood supply. Repeated execution of certain task and subsequent fast MRI scanning represent neuronal activation of responsible foci for the task. As it has a siginificant role in functional neuroimaging, fMRI is currently applied in many filed of brain research, particularly on the evaluation of brain function and structure. fMRI is particularly useful in the clinical field of neurodegenerative disease including dementia, cerebrovascular disease, and epilepsy.

Visual Segmentation is an important function of our visual system as it eventually enables us to form correct representation of the outer world objects or events. We used fMRI in search for cortical activity related to the perception of visual scene segmented by contrast of three visual cues in human beings. The stimuli used were three kinds of flickering random dot checkerboard: defined by 1)texture orientation contrast 2)color contrast 3)motion direction contrast. Using these stimuli, 9 healthy subjects were functionally scanned with 1.5T MR machine while they fixated their eyes and passively viewed the stimuli presented. In experiment 1, these three conditions sequentially appeared from a flickering random dot field, while in experiment2 they appeared from a dark screen with fixation point in the center. Even though all three checkerboard conditions were the same in both experiments, the overall activation patterns were quite different. The extrastriate areas, especially V4, and Parietal lobe were activated cue-invariantly in the first experiment, while only V1 was activated cue-invariantly in the second experiment. To investigate the effect of the flickering random dot field, experiment3 was carried out with 4 of the ex-subjects and it showed activation of V1 and deactivation of extrastriate area including MT area for the flickering random dot field perception. As flickering effect might have removed the V1 activation in experiment1 while comparing checkerboard conditions with flickering random dot field condition, it can explain the absence of V1 activation in experiment1, still it cannot explain the absence of V4 activation or Parietal lobe activation in experiment2. As V1 has been localized for boundary perception and V4 for shape perception and parietal lobe for binding different visual attributes, activation of these areas can be interpreted as such. However, the differences in the results of experiment1 and experiment2 suggest that differences of the start line in perceptual flow can activate visual cortices differentially.

Mirror movements in adult is usually accompanied with various clinical syndromes. But the pathogenesis of mirror movement is not clearly understood. A 20-years old man visited with complaining of mirror movements in both hands, ophthalmoplegia and sensorineural hearing loss. He underwent through electromyography, transcranial magnetic stimulation, and functional magnetic resonance image. And we concluded that the mechanisms of his mirror movements were both ipsilateral innervated corticospinal tract and simultaneous activation of both motor cortex.

Two hemiplegic cerebral palsy patients were studied to investigate the cortical mechanisms underlying preserved somatosensory capacity, using functional MRI(fMRI). Tactile stimulation was performed by brushing of palm, during fMRI study. By the affected hand stimulation, contralateral primary somatosensory cortex was activated in patient 1 and cortical area anterior to the lesion site was activated in patient 2. We suggest that reorganization of the somatosensory cortex after brain injury can be induced by recruitment of undamaged areas adjacent to lesion site.

The diagnosis of peripheral neuropathy had been performed by electrophysiologic studies and neurologic examination. However, Magnetic Resonance Imaging (MRI) has recently been proposed as a supplementary tool for its diagnosis. A 55-year-old woman presented with back pain and painful proximal weakness of the right leg. Neurologic examination and electrophysiologic studies suggested an upper lumbar plexopathy. MRI disclosed the signal change in lumbar plexus with the atrophy of the innervating muscles. We report a patient with idiopathic lumbar plexopathy confirmed by MRI.

Functional neuroimaging, especially positron emission tomography (PET) and functional magnetic resonance imaging (MRI), is the main tool that allows the unveiling of the neurovascular events during a migraine attack. In migraine with aura, functional neuroimaging has contributed greatly to the understanding of the fundamental pathophysiology of the visual aura, whereas in migraine without aura, the PET findings of brainstem activation suggest a pivotal role of brainstem in the generation of migraine headache. In addition, voxel-based morphometry (VBM) method has provided an insight into the morphometric changes of the brain, which might be considered as a consequence of repeated migraine attacks. In this article, I will briefly discuss the main neuroimaging findings pertaining to the pathophysiology of migraine.

Even though the origin and nature of nocturnal paroxysmal dystonia (NPD) remains unclear, it has been considered as a manifestation of the nocturnal frontal lobe epilepsy. We report a 17-year-old man with abnormal stereotyped movement during sleep. Video-EEG monitoring, ictal SPECT and night polysomnography did not show any evidence of epilepsy. However, the partial response to large dose of carbamazepine and the scoring according to the frontal lobe epilepsy and parasomnias (FLEP) scale suggest his events could be classified as epilepsy. Therefore we think the FLEP scale might be a useful tool for differential diagnosis in a patient presenting NPD.

Background
& Purpose : Dynamic susceptibility contrast MR imaging, one method of perfusion MRI, was developedto define cerebral hemodynamic status with good anatomical resolution. The authors investigated hemodynamicparameters using this imaging method, in an effort to identify hemodynamic changes on the remote crossed cerebellumof patients with a supratentorial infarct.Methods : Dynamic susceptibility contrast MR imaging was performed in 15 patients with only unilateral supratentorialinfarcts. Imaging was obtained at the anatomic level of the cerebellum. rCBF, rCBV, MTT and TP were determinedover both cerebellar hemispheres of interest.Results : The rCBF and rCBV values of the contralateral cerebellar hemisphere were significantly more decreasedthan those of the ipsilateral cerebellar hemisphere in 12 patients(p=0.028, 0.033). MTT and TP values of the contralateraland ipsilateral cerebellar hemispheres didn