Impairment of spatial memory and changes in astroglial responsiveness following loss of molar teeth in aged SAMP8 mice

In order to evaluate the mechanism(s) responsible for senile impairment of cognitive function as a result of reduced mastication, the effects of the loss of the molar teeth (molarless condition) on the hippocampal expression of glial fibrous acidic protein (GFAP) and on spatial memory in young adult and aged SAMP8 mice were studied using immunohistochemical and behavioral techniques. Aged molarless mice showed a significantly reduced learning ability in a water maze test compared with age-matched control mice, while there was no difference between control and molarless young adult mice. Immunohistochemical analysis showed that the molarless condition enhanced the age-dependent increase in the density and hypertrophy of GFAP-labeled astrocytes in the CA1 region of the hippocampus. These effects increased the longer the molarless condition persisted. When the extracellular K+ concentration ([K+]o) was increased from 4 to 40 mM for hippocampal slices in vitro, the mean increase in the membrane potential was about 57 mV for fine, delicate astrocytes, the most frequently observed type of GFAP-positive cell in the young adult mice, and about 44 mV for the hypertrophic astrocytes of aged mice. However, there was no significant difference in resting membrane potential between these cell types. The data suggest that an impairment of spatial memory and changes in astroglial responsiveness occur following the loss of molar teeth in aged SAMP8 mice.

Reduced size of the cochlear branch of the vestibulocochlear nerve in a child with sensorineural hearing loss

A 12-year-old female patient presented with unilateral sensorineural hearing loss. Distortion-product otoacoustic emission testing failed to reveal any measurable emissions in the affected side. MR imaging did not reveal labyrinthine malformation. Three-dimensional Fourier transformation-constructive interference in steady-state MR images showed a thin cochlear branch. We speculated that mumps infection or developmental malformation caused the unilateral sensorineural hearing loss.

Novel mutations in the connexin 26 gene (GJB2) responsible for childhood deafness in the Japanese population

Mutations in the connexin 26 gene (GJB2), which encodes a gap-junction protein and is expressed in the inner ear, have been shown to be responsible for a major part of nonsyndromic hereditary prelingual (early-childhood) deafness in Caucasians. We have sequenced the GJB2 gene in 39 Japanese patients with prelingual deafness (group 1), 39 Japanese patients with postlingual progressive sensorineural hearing loss (group 2), and 63 Japanese individuals with normal hearing (group 3). Three novel mutations were identified in group 1: a single nucleotide deletion (235delC), a 16-bp deletion (176-191 del (16)), and a nonsense mutation (Y136X) in five unrelated patients. The 235delC mutation was most frequently observed, accounting for seven alleles in 10 mutant alleles. Screening of 203 unrelated normal individuals for the three mutations indicated that the carrier frequency of the 235delC mutation was 2/203 in the Japanese population. No mutation was found in group-2 patients. We also identified two novel polymorphisms (E114G and I203T) as well as two previously reported polymorphisms (V27I andV37I). Genotyping with these four polymorphisms allowed normal Japanese alleles to be classified into seven haplotypes. All 235delC mutant alleles identified in four patients resided only on haplotype type 1. These findings indicate that GJB2 mutations are also responsible for prelingual deafness in Japan.

Purification and characterization of a 49-kDa chitinase from Streptomyces griseus HUT 6037

A 49-kDa chitinase (pI7.3) was purified to homogeneity from the culture supernatant of Streptomyces griseus HUT 6037 by ultrafiltration, DEAE-Sephadex A-50 and Sephadex G-100 column chromatographies, and chromatofocusing. The purified enzyme was stable up to 40 degrees C. The N-terminal amino acid sequence of the enzyme was highly homologous to the N-terminal region of the fibronectin type III-like domain of S. olivaceoviridis chitinase 01 belonging to family 18 glycosyl hydrolases. The 49-kDa chitinase hydrolyzed partially N-acetylated chitosan more easily than colloidal chitin. The hydrolyzate of 54% deacetylated chitosan by the enzyme was separated by CM-Sephadex C-25 column chromatography. The structures of the oligosaccharides obtained were determined by MALDI-TOF MS analysis combined with exo-glycosidase digestion. In addition to GlcNAc, (GlcNAc)2, and (GlcNAc)3, hetero-chitooligosaccharides with GlcNAc at the reducing end were detected. Thus, the specificity of the enzyme for the hydrolysis of the beta-1,4-glycosidic linkages in partially N-acetylated chitosan was similar to that of the family 18 chitinases.

Glycerol attenuates the adherence of leukocytes in rat pial venules after transient middle cerebral artery occlusion

Intravenous infusion of glycerol has been used in patients with a cerebral infarction, expecting improvement in brain edema and cerebral blood flow (CBF). However, the mechanism of the improvement of CBF has not been clearly demonstrated. The aim of this study in the rat pial microvasculature after transient middle cerebral artery occlusion (MCAO) is to examine the effects of glycerol on leukocyte-endothelium interaction, which plays a critical role in the pathogenesis of brain injury by ischemia/reperfusion and concerns induction of secondary brain damage. Rhodamine 6G-labeled leukocytes at the brain surface were visualized with intra-vital fluorescence videomicroscopy through a closed cranial window and an analysis was made of the number of adherent leukocytes and the centerline leukocyte velocity in the venule before MCAO, after reperfusion of MCAO and after infusion of glycerol (Group 1) or saline (Group 2). The number of adherent leukocytes decreased and the centerline leukocyte velocity increased statistically significantly immediately after the infusion of glycerol in Group 1, but there was no significant change in Group 2. The infusion of glycerol washes away the adherent leukocytes and prevents them from interfering with the blood cell and plasma flow. Furthermore, secondary brain damage may be relieved by decreasing the adherence of leukocytes. In conclusion, modulating the adherence of leukocytes is one of the important factors in the neuroprotective effect of glycerol.

Zygomatic arch cracking for cosmetic improvement: technical note

We describe a simple cracking method for removing the zygomatic arch. The drilling line of the zygomatic arch is partially drilled from the back, and the surface is left undrilled. The zygomatic arch is cracked during its removal in order to secure its position for later fixation. Dead bone spaces can be avoided by this method and the zygomatic arch can be replaced in its original position. By adding this procedure to the standard technique, this cracking method is a simple, safe and useful way to achieve better cosmetic results.

[Aortic valve papillary fibroelastoma in a patient with mitral valve regurgitation]

Papillary fibroelastoma is a rare cardiac tumour. We describe a patient with mitral valve regurgitation and aortic valve papillary fibroelastoma. The patient was 62-year-old woman. She was referred to us for surgical treatment of mitral valve. Preoperative echocardiography showed rheumatic mitral valve regurgitation (Sellers grade III) and it also demonstrated mobile masses of the aortic valve. At operation, mitral valve was repaired by a posterior annuloplasty. Through the aortotomy, small tumors were found to be attached to each cusps of the aortic valve and they were successfully removed. The histopathologic diagnosis was papillary fibroelastoma of the aortic valve. The postoperative course was uneventful.

Preoperative tumor embolization

We performed an embolization of tumors which we considered to need preoperative embolization, such as deep-seated tumors, or hypervascular tumors. We experienced 12 such cases in the two-year period from September 1996. Eight cases were meningiomas, one case was a hemangiopericytoma, one case was an angiofibroma and two cases were glomus tumors. As embolic material, we usually use estrogen-alcohol and polyvinyl acetate which soften the tumor. When a provacative test is either impossible or positive, the distal induction of a microcatheter is impossible or a dangerous anastomosis is present, we select polyvinyl alchol particles (120 approximately 250mum) and liquid coils. We performed an embolization of a very hypervascular tumor, juvenile angiofibroma, by a direct tumor puncture, using a mixure of N-butylcyanoacrylate, lipiodol and tantalum powder. Angiography in all cases showed a reduction of the tumor stain. The embolic method should be selected based on a combination of such factors as the purpose of embolization, the identification of the feeding artery and the histological findings.

Profound hearing loss attributable to cochlear nerve disease: diagnosis with combination of otoacoustic emission and magnetic resonance imaging

OBJECTIVE

To detect the causes of deafness based on the combined findings of auditory brainstem response (ABR), distortion product otoacoustic emissions (DPOAEs), and three-dimensional Fourier transformation-constructive interference in steady state (3DFT-CISS) magnetic resonance imaging (MRI).

STUDY DESIGN

Retrospective review of the medical records of 13 patients with unilateral profound hearing loss since childhood.

METHODS

Subjects were tested with pure-tone audiometry, ABR, DPOAEs, and 3DFT-CISS imaging.

RESULTS

No significant components of ABR were observable in any of the deaf ears. In 10 cases, the cochlear nerves of the deaf ears were found to be as normal as the healthy sides by 3DFT-CISS imaging, and no significant levels of DPOAEs were recorded. In the other three cases, no apparent cochlear nerves were identified by 3DFT-CISS imaging. Although no significant levels of DPOAEs were observable in two cases with cochlear nerves invisible by the MRI study, almost the same level of DPOAEs as that in the healthy side was recorded in the last case.

CONCLUSIONS

In the last particular case, the cochlear nerve seemed to be mainly responsible for the profound deafness. 3DFT-CISS imaging in combination with preexisting audiological measures may provide direct evidence for the cochlear nerve disease. steady state, internal auditory canal, cochlear nerve disease.

Age-associated changes in the dopamine synthesis as determined by GTP cyclohydrolase I inhibitor in the brain of senescence-accelerated mouse-prone inbred strains (SAMP8)

Our objective in this study was to elucidate the mechanism underlying the decrease in dopamine (DA) levels in the brain with ageing We administered 2,4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor of GTP cyclohydrolase I to senescence-accelerated mouse-prones (SAMP8), to inhibit DA and serotonin syntheses, and following immunohistochemical staining, analyzed the immunoreactive intensities (IR-Is) for DA in the nigrostriatal dopaminergic neurons by microphotometry. The DA-IR-Is in the substantia nigra pars compacta and neostriatum of young mice (2 months old) reached a minimal value 3 h after DAHP administration and returned to the control value 12 h after the administration. However, in aged mice (10 months old), the minimal value was reached 6 h after the administration and the value remained at approximately 70 and 80% of the control value at 24 and 72 h, respectively, after DAHP administration. The results suggest that DA turnover is lower in aged mice than in young mice.

Effects of mechanical stress on the mRNA expression of S100A4 and cytoskeletal components by periodontal ligament cells

The periodontal ligament (PDL) functions under constant mechanical stress, and PDL cells obviously control PDL functions under such conditions. We have previously found that the mRNA expression of the Ca2+-binding protein S100A4 and beta-actin is higher in the PDL from erupted teeth than in the PDL from teeth under eruption. This suggested a role for S100A4 in the response of PDL cells to mechanical stress, possibly by coupling Ca2+ and the cytoskeletal system. In the present study, we investigated the direct effects of cyclical stretching on the mRNA expression of S100A4 and two cytoskeletal components (beta-actin and alpha-tubulin) by PDL cells. In Northern blotting analysis, the expression of S100A4, beta-actin, and alpha-tubulin mRNAs was higher in the PDL from fully erupted and functional bovine teeth than in partially erupted ones. Similarly, when bovine PDL cells were mechanically stimulated by means of the Flexercell Strain Unit, the expression of S100A4, beta-actin, and alpha-tubulin mRNAs increased over the control levels. The results of our present study indicate that S100A4 is involved in the responses of PDL cells to mechanical stress possibly by coupling Ca2+ to the cytoskeletal system in these cells.

Altered cochlear fibrocytes in a mouse model of DFN3 nonsyndromic deafness

DFN3, an X chromosome-linked nonsyndromic mixed deafness, is caused by mutations in the BRN-4 gene, which encodes a POU transcription factor. Brn-4-deficient mice were created and found to exhibit profound deafness. No gross morphological changes were observed in the conductive ossicles or cochlea, although there was a dramatic reduction in endocochlear potential. Electron microscopy revealed severe ultrastructural alterations in cochlear spiral ligament fibrocytes. The findings suggest that these fibrocytes, which are mesenchymal in origin and for which a role in potassium ion homeostasis has been postulated, may play a critical role in auditory function.

Trigeminal neurinomas extending into multiple fossae: surgical methods and review of the literature

OBJECT

Since 1974, 27 patients with trigeminal neurinomas (TNs) have been treated at Keio University Hospital and ancillary institutes. In the present study the clinical features and developmental patterns of these 27 cases are analyzed, and the clinical features of 402 cases reported in the literature are reviewed. Based on the analysis of the developmental patterns of the TNs, the surgical strategy for a one-stage removal of TNs involving multiple fossae is described.

METHODS

Trigeminal neurinomas are classified into six types according to tumor location. Types M, P, and E are tumors involving a single compartment, that is, the middle fossa, posterior fossa, or extracranial space, respectively. Types MP (middle and posterior fossae), ME (middle fossa and extracranial space), or MPE (middle and posterior fossae and extracranial space) are tumors involving multiple compartments. Advances in neuroimaging technologies, such as magnetic resonance imaging, have revealed a high incidence of TNs extending into multiple fossae, namely 36.2% in cases reported since 1983 and 59% in the authors' series. All but one of the most recent 19 patients in this series underwent skull base surgery, whereas the remaining nine patients were surgically treated via the conventional subdural approach. The rate of total tumor removal and the clinical outcome were significantly better in those patients treated by skull base surgery than those treated by conventional surgery.

CONCLUSIONS

The TNs extending into multiple fossae can be totally removed using the following single-stage surgical techniques: Type MP by the anterior transpetrosal approach; Type ME by the zygomatic or orbitozygomatic infratemporal approach; and Type MPE by the zygomatic transpetrosal approach. In 12 of 13 cases involving multiple fossae in this series, total tumor removal was achieved using single-stage skull base surgery.

Effects of moderate hypothermia on leukocyte- endothelium interaction in the rat pial microvasculature after transient middle cerebral artery occlusion

Background and Purpose--It has been demonstrated that moderate hypothermia attenuates brain damage, but the mechanism whereby this is achieved has not been clearly shown. Recently, the role of leukocytes as mediators of secondary brain damage after brain ischemia has been discussed. The aim of this study is to examine the effects of moderate hypothermia on leukocyte-endothelium interaction in the rat pial microvasculature after transient middle cerebral artery occlusion (MCAO). Methods--Rhodamine 6G-labeled leukocytes in brain surface were visualized with intravital fluorescence videomicroscopy through a closed cranial window. We analyzed the number of leukocytes adhering to the venular and arteriolar endothelium before ischemic insult and up to 3 hours after reperfusion. Rats were divided into 4 experimental groups. Group I (n=6) consisted of sham-operated animals. Groups II (n=6) and III (n=6) received left MCAO for 1 hour under normothermia (36 degrees C to 37 degrees C, group II) and under moderate hypothermia (30 degrees C to 32 degrees C, group III). Group IV (n=4) received left common carotid artery occlusion for 1 hour under normothermia. Results--The number of adhering leukocytes in venules in groups II and IV increased significantly (P<0.001) after reperfusion compared with the group I, but that in group III did not increase significantly (P>0.05). The number of adhering leukocytes in arterioles in group II increased significantly (P<0.01) compared with the other groups, although the adhering leukocytes were not as numerous as those seen in venules. Conclusions--It is demonstrated that hypothermia attenuates adhering leukocytes in venules and arterioles after reperfusion of MCAO. The inhibition of the leukocyte function may be an important factor in the neuroprotective effect of hypothermia.

Differentiation and angiogenesis of central nervous system stem cells implanted with mesenchyme into ischemic rat brain

After cerebral infarction, necrosis in neural tissues is not usually repaired or reconstructed by the injured brain. We therefore examined the effects on postinfarction repair of implanting central nervous system (CNS) stem cells together with mesenchyme, because CNS stem cells can be expected to adapt and survive in the adult brain. Cerebral infarction was induced by the Koizumi-Longa method, using the adult male spontaneous hypertensive rat model. Reperfusion was performed an hour after middle cerebral artery occlusion. The rat mesencephalic neural plate at the early somite stage (embryonic day 10.5) together with the adjacent ventral mesenchymal tissues was dissected out under the microscope and immediately implanted into the ischemic rat striatum. One month later, the cognitive function was evaluated by the Morris water maze method. Histologic and immunohistochemical examinations of the graft were made with hematoxylin-eosin (H&E), neurofilament-200, and tyrosine hydroxylase (TH) stains. In the water maze study, mean latency times required to reach an escape platform in the implanted animals with surviving grafts were found to be shorter than in those without grafts, but longer than in normal animals. In the spatial probe trial, the number of animals seen to cross the area in the pool where the platform had been located was greater in the implanted rats with surviving grafts than in other groups. Multiple vascularization in the grafted area was observed histologically in H&E-stained tissues, and neurofilament-200-positive cells were recognized in the graft. TH staining revealed within the graft many immunoreactive neuron-like cell bodies with long dendrites. It was suggested that grafted CNS stem cells with mesenchyme may survive and differentiate into mature CNS tissue within the adult ischemic rat brain, constructing vessels in and around the grafts, and may therefore have the potential to be effective in the recovery of the cognitive function of the rat model.

Cytokine secretion of periodontal ligament fibroblasts derived from human deciduous teeth: effect of mechanical stress on the secretion of transforming growth factor-beta 1 and macrophage colony stimulating factor

The periodontal ligament may play an important role in tooth eruption, root development and resorption. The tissue physiologically receives mechanical force during mastication. We focused on the effects of intermittent mechanical strain on the cytokine synthesis of periodontal ligament (PDL) fibroblasts in vitro. The cells were derived from human periodontal ligament of deciduous teeth (HPLF-Y) and permanent teeth (HPLF). The two kinds of PDL cells and human gingival fibroblasts (HGF) were cultured in flexible bottomed culture plates. The cells were mechanically stretched at 5% elongation, 3-cycles/min for 24 h on d 7 in culture using a Flexercell strain unit. After the stretching, we measured DNA content and alkaline phosphatase activity in the cell layer, transforming growth factor beta 1 (TGF-beta 1) and macrophage colony stimulating factor (M-CSF) contents in the conditioned medium. The TGF-beta 1 level in the conditioned medium of HPLF was significantly higher than that of HPLF-Y and HGF. It was stimulated by mechanical stretching only on HPLF, whereas no significant effect was observed on HPLF-Y and HGF. M-CSF secretion was inhibited by the stretching on all of HPLF, HPLF-Y and HGF. 1 alpha, 25 dihydroxy vitamin D3 (D3) stimulated M-CSF secretion into the culture medium of both HPLF and HPLF-Y, but the stretching inhibited M-CSF secretion and completely blocked the enhancement by D3. These data suggest that periodontal ligament cells synthesize and secrete the molecules as autocrine or paracrine factors that affect bone remodelling and root resorption and the level of those factors change in response to mechanical stress.

The excitation site of the accessory nerve to the magnetic stimulation--the relationship between the orientation of the magnetic field and the excitation site

OBJECTIVE

The relationship between the accessory nerve excitation site and the magnetic field direction was investigated to prove whether the cranial nerve excitation site to the transcranial magnetic stimulation is constant or not.

METHODS

Compound muscle action potentials (CMAPs) elicited by the transcranial magnetic stimulation were recorded from the trapezius muscles of 7 adult cats. The waveforms of CMAPs were detected before craniectomy, after craniectomy, and after cutting the accessory nerve at the C1, at the jugular tubercle, and at the jugular foramen. The optimal orientation was determined by rotating the coil clockwise in increments of 22.5 degrees from the rostral direction.

RESULTS

The accessory nerve was stimulated by the magnetic stimulation at the C1, at the jugular tubercle or at the jubular foramen, and these excitation sites varied with coil orientation. The average angles of the optimal orientation of the magnetic coil were 77.1 degrees for C1, 122.1-263.6 degrees for the jugular tubercle, and 308.6-32.1 degrees for the jugular foramen.

CONCLUSIONS

The accessory nerve excitation site varied with the orientation of the magnetic coil. This study suggested the possibility of a variety of the cranial nerve excitation sites to the transcranial magnetic stimulation.

Prospective study of interferon therapy for compensated cirrhotic patients with chronic hepatitis C by monitoring serum hepatitis C RNA

Because interferon therapy exhibits low efficacy for cirrhotic patients infected with hepatitis C virus, this prospective study was conducted to determine effective interferon regimens tailored to treatment response by monitoring HCV RNA status. A total of 157 cirrhotic patients were enrolled to receive 9 million units (MU) of interferon three times a week. The HCV RNA values were drawn 8 weeks apart and the patients were randomized to a further 16 or 32 weeks of treatment after two sequential findings of negativity for HCV RNA. A total of 73 out of 157 patients (46%) proceeded to randomization to different durations of treatment, 37 short-course and 36 long-course (duration: 38 +/- 8 and 49 +/- 13 weeks; total amount of interferon: 940 +/- 240 and 1130 +/- 390 MU, respectively). The remaining 84 patients without two sequential negative serum HCV RNA determinations received 44.8 +/- 27.4 weeks of interferon (IFN) therapy with total amount of 993 +/- 633 MU. Of these 157 patients, sustained virological and biochemical response was shown in 32 (20%) and 37 patients (24%), respectively. Sustained virological and biochemical response rate in the randomized patients was significantly higher than in nonrandomized patients (41% vs. 2%, and 38% vs. 11%; each P <.01). Of the 73 randomized patients, the rate of sustained virological response in patients with long-course treatment (50%) was significantly higher than that of patients with short-course treatment (32%) (P =.026: log-rank test), and in patients with early disappearance of HCV RNA especially within 8 weeks, in patients with low virus load (</=10(6.3) copies/mL) and with HCV 2a. Multivariate analysis revealed that HCV RNA level and subtypes were the most important factors contributing to sustained virological response. Interferon is effective even in cirrhotic patients with low viral load and HCV 2a, but requires a longer course of administration.

Morphological characterization and subtyping of silent somatotroph adenomas

GH-producing adenomas clinically are endocrine-active tumors accompanied with acromegaly in most instances. However, GH-producing adenomas apparently unassociated with acromegaly, or so-called silent somatotroph adenomas (SSA), have recently been reported but rarely. The reported cases are characterized by normal or slightly elevated serum levels of GH but without acromegaly. Tumor cells contain moderate, trace or no GH immunoreactivity. We experienced 7 cases of SSA which were not always similar in morphology and pathogenetic mechanism. They could be further divided into the following 3 subtypes. Subtype 1 (N = 2): a moderate number of cells were immunopositive for GH, and GH mRNA was also expressed in moderate or numerous cells. Densely granulated cells were noted. It is assumed that inhibition of hormone release into circulation. Subtype 2 (N = 3): a small number of cells were immunopositive for GH, while GH mRNA was expressed in numerous tumor cells. They were sparsely granulated cells containing fibrous bodies. These findings suggest that posttranslational processing of the gene product may be defective. Subtype 3 (N = 2): Only a scattered number of cells were immunopositive for GH and GH mRNA was co-localized in immunopositive cells. They were sparsely granulated cells containing poorly developed organelles that did not resemble those of typical sparsely granulated GH cells. The findings indicate that adenoma cells are largely immature with minimal GH lineage differentiation.

Prognosis of sudden deafness with special reference to risk factors of microvascular pathology

OBJECTIVE

We attempted to elucidate the contribution of microvascular disorders as risk factors to the prognostic outcome in well-defined patients with sudden deafness.

METHODS

One-hundred and thirty-two patients diagnosed as unilateral sudden deafness were retrospectively analyzed. Auditory function was determined by pure-tone audiometry. Diabetes, hyperlipidemia, and hypertension were considered as microvascular diseases.

RESULTS

Concurrent microvascular diseases were recognized in 38 patients. Although the hearing disturbance at the first visit showed no difference from patients without concurrent diseases, a better outcome of hearing was obtained in patients without the concurrent diseases.

CONCLUSION

The poor prognosis observed in patients with the concurrent diseases is likely to have been brought about by preexisting microvascular disease of the hearing organ, which is highly affected by aging.

F-waves of the facial muscles in healthy control subjects and in patients with peripheral facial nerve disturbance

F-waves were recorded from the mentalis muscles with surface electrodes following stimulation of the marginal mandibular branch of the facial nerve in healthy control subjects during wakefulness, non-REM (rapid eye movement) sleep and voluntary contraction and in patients with Bell's palsy and acoustic neurinoma. The F-wave of the facial muscles results from the backfiring of antidromically activated alpha motoneurons in the facial motonucleus. Therefore, first, the F-waves were not easily elicited in patients with any disturbance in the proximal segment of the facial nerve (Bell's palsy and acoustic neurinoma). Second, the F-waves were affected by excitability of the facial motonucleus; the F-waves were inhibited significantly during sleep and enhanced significantly during voluntary contraction compared with those at rest during wakefulness. When the stimulation strength was set submaximum for M-waves, F-waves were elicited but H-waves, which have lower threshold than M-waves, were not elicited in the facial muscles, unlike the case of the extremities. Measurement of the F-waves of facial muscles is a new method for estimating excitability of the facial motonucleus unless there is any disturbance of the proximal segment. Fundamental characteristics of the facial F-waves were shown in the present study and measuring facial F-waves is clinically applicable for investigation of both excitability of the facial motonucleus and facial peripheral nerve disturbance.