Obesity, glucose intolerance, advanced age, and lymphocytopenia are independent risk factors for oxygen requirement in Japanese patients with Coronavirus disease 2019 (COVID-19).

At the current time of rising demand for hospital beds, it is important to triage COVID-19 patients according to the treatment needed during hospitalization. The need for oxygen therapy is an important factor determining hospital admission of these patients. Our retrospective study was designed to identify risk factors associated with the progression to oxygen requirement in COVID-19 patients. A total of 133 patients with laboratory-confirmed COVID-19 were admitted to our hospital from February 22, 2020, to August 23. After excluding asymptomatic, non-Japanese, pediatric, pregnant patients and also those who needed oxygen immediately at admission, data of the remaining 84 patients were analyzed. The patients were separated into those who required oxygen after admission and those who did not, and their characteristics were compared. Age, body mass index (BMI), lymphocyte count, C-reactive protein (CRP), lactate dehydrogenase, estimated glomerular filtration rate, glucose intolerance, hypertension, and dyslipidemia were significantly different between the two groups. Multivariate analysis identified four significant and independent risk factors of oxygen requirement, including advanced age, obesity, glucose intolerance and lymphocytopenia. Dividing the patients into subgroups according to the number of these risk factors found in each patient indicated that the need for oxygen increased with higher number of these risk factors in the same individual. Our results suggest that the presence of higher number of these risk factors in COVID-19 patients is associated with future oxygen requirement and that this index can be potentially useful in triaging COVID-19 patients staying home in the context of need for hospitalization.

[A case of adult-onset Sturge-Weber syndrome type III without intracranial calcification, presenting with transient homonymous hemianopia].

Sturge-Weber syndrome (SWS) is a rare neurocutaneous disorder. Almost all cases of SWS are diagnosed in children, but some are diagnosed in adults. We describe a case of isolated leptomeningeal angiomatosis without intracranial calcification. A 33-year-old woman was admitted because of sudden-onset right homonymous hemianopia with headache and nausea. These symptoms disappeared by the next morning. She had no history of seizure or mental retardation. No facial angioma was found on physical examination. Brain CT showed no intracranial calcification or atrophic cortex. The blood and cerebrospinal fluid analyses yielded normal results. The findings in the electroencephalogram were unremarkable. MRI with susceptibility weighting (SWI) revealed dilated transmedullary veins in the left occipital lobe. Contrast-enhanced T1-weighted imaging (CE-T1WI) illustrated abnormal leptomeningeal enhancement in the left occipitoparietal cortex and enhancement and enlargement of the choroid plexus in the left lateral ventricle. Post-gadolinium contrast-enhanced f FLAIR imaging demonstrated more extensive enhancement of the leptomeningeal lesions than did CE-T1WI. The symptoms and the findings on these images were suggestive of a diagnosis of SWS type III. Clinicians should keep in mind that some cases of SWS manifest with only minor symptoms, such as migraine. If SWS is suspected, SWI and contrast-enhanced MRI should be performed.

Thrombolysis and Mechanical Thrombectomy for Acute Ischemic Stroke in Pregnancy: A Case Report.

Objective: Intravenous (IV) recombinant tissue plasminogen activator (rt-PA) and mechanical thrombectomy (MT) are effective treatments for acute ischemic stroke (AIS). However, the treatment for AIS in pregnancy is not established because no clinical trials have included pregnant patients. We present a case of middle cerebral artery (MCA) M2 segment occlusion in pregnancy treated with IV thrombolysis and endovascular therapy. Case Presentation: A 36-year-old woman being 6 weeks pregnant presented with right-sided hemiparesis and aphasia. MRI showed a high-intensity area on diffusion-weighted imaging of the left parietal lobe, and MRA showed left MCA M2 segment occlusion. She underwent IV rt-PA and MT and achieved thrombolysis in cerebral infarction 2b revascularization without complications. The protein S concentration was lower than that in the physiological changes during pregnancy. She was diagnosed with embolic stroke related to coagulopathy in pregnancy, and she underwent anticoagulation. At the 3-month follow-up, the modified Rankin Scale was 0. She miscarried at 4 months, and the fetal death was presumed to be obstetric cause. Conclusion: IV rt-PA and MT may be effective and safe treatments for pregnant patients. Estimated fetal radiation exposure during MT is low and is presumed not to affect fetal development. We should mitigate the radiation dose and reduce the dose of iodinated contrast agents, particularly in pregnant patients.

Early clinical factors predicting the development of critical disease in Japanese patients with COVID-19: A single-center, retrospective, observational study.

The factors predicting the progression of coronavirus disease-2019 (COVID-19) from mild to moderate to critical are unclear. We retrospectively evaluated risk factors for disease progression in Japanese patients with COVID-19. Seventy-four patients with laboratory-confirmed COVID-19 were hospitalized in our hospital between February 20, 2020, and June 10, 2020. We excluded asymptomatic, non-Japanese, and pediatric patients. We divided patients into the stable group and the progression group (PG; requiring mechanical ventilation). We compared the clinical factors. We established the cutoff values (COVs) for significantly different factors via receiver operating characteristic curve analysis and identified risk factors by univariate regression. We enrolled 57 patients with COVID-19 (median age 52 years, 56.1% male). The median time from symptom onset to admission was 8 days. Seven patients developed critical disease (PG: 12.2%), two (3.5%) of whom died; 50 had stable disease. Univariate logistic analysis identified an elevated lactate dehydrogenase (LDH) level (COV: 309 U/l), a decreased estimated glomerular filtration rate (eGFR; COV: 68 ml/min), lymphocytopenia (COV: 980/µl), and statin use as significantly associated with disease progression. However, in the Cox proportional hazards analysis, lymphocytopenia at admission was not significant. We identified three candidate risk factors for progression to critical COVID-19 in adult Japanese patients: statin use, elevated LDH level, and decreased eGFR.

[Ictal EEG pattern of transient epileptic amnesia in acute phase of non-herpetic limbic encephalitis].

A 60-year-old, right-handed woman was admitted to our hospital for amnesia as the only neurological abnormal findings following the autonomic symptoms and transient episodes of loss of awareness. EEG during the amnesia showed rhythmic alpha activity arising from the left mid-temporal region. Although this ictal activity showed evolution in the frequency and amplitude, the location was limited in the bilateral temporal areas. After the EEG evaluation, her amnesia was resolved immediately, suggesting that her presentation was transient epileptic amnesia (TEA). Meanwhile, given the clinical course and MRI findings (high intensity in the bilateral mesial temporal areas, more on the left), she was diagnosed with non-herpetic limbic encephalitis and treated with steroid and anti-epileptic drugs, leading to the positive outcome. The ictal EEG findings during TEA as the one of the presentation in acute phase of non-herpetic limbic encephalitis may contribute to further investigation of underlying mechanism of TEA.

Increased number of mitochondria in capillaries distributed in stroke-like lesions of two patients with MELAS.

We investigated two autopsy cases of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) using immunohistochemical staining with an anti-mitochondrial antibody against translocase of the outer membrane 20 (TOMM20). In case 1, the patient was a 42-year-old man with a disease duration of 53 days, and in case 2, the patient was a 62-year-old woman with a disease duration of 27 months. In both the cases autopsy revealed moderate atrophy of the cerebrum and cerebellum and multifocal necrotizing lesions, irrespective of the vascular territory. Case 1 showed multiple areas with total necrosis in the cortex, accompanied by increases in number of protoplasmic astrocytes and acidophilic neurons as well as axonal swelling, suggestive of acute or subacute stage stroke-like lesions (SLLs). In case 2, most of the SLLs displayed laminar spongy change in a rarefied cortex, and were considered to be at the chronic stage. In both the cases, capillary proliferation was noted within the SLLs, particularly in the acute phase. Endothelial cells of proliferating capillaries were strongly positive for TOMM20. In the cortex outside the SLLs, microvessels displayed only a fine granular immunoreactivity, as is seen in the controls. Although smooth muscle cells and endothelial cells in pial arteries and arterioles were also strongly positive for TOMM20, the territories of the affected pial arteries and arterioles did not correlate with the distribution of the SLLs. Although MELAS is characterized by recurrent stroke-like episodes (SLEs), the pathogenetic relationship between SLEs and mitochondrial angiopathy remains unknown. An aberrant increase of mitochondria in the capillary endothelial cells of SLLs may disturb endothelial function, thus playing a role in the formation or development of SLLs.

The optimal stimulation site for high-frequency repetitive transcranial magnetic stimulation in Parkinson's disease: A double-blind crossover pilot study.

Many reports have shown improvements in motor symptoms after repetitive transcranial magnetic stimulation (rTMS). However, the best stimulation area in the brain has not currently been determined. We assessed the effects of high-frequency rTMS (HF-rTMS) on the motor and mood disturbances in Parkinson's disease (PD) patients and attempted to determine whether the primary motor area (M1), the supplementary motor area (SMA), and the dorsolateral prefrontal cortex (DLPFC) were the best treatment targets. In this randomized, double-blind crossover design study, we investigated the efficacy of 3 consecutive days of HF-rTMS over the M1, SMA, and DLPFC and compared these HF-rTMS to sham stimulations. We used motor and non-motor scales to evaluate the parkinsonian symptoms. The changes in the Unified Parkinson's Disease Rating Scale part III (UPDRS-III) scores after the application of HF-rTMS over the M1 and SMA were significantly greater than those after the sham stimulation. However, after the application of HF-rTMS over the DLPFC, the UPDRS-III scores were similar to those after the sham stimulation. No significant improvements were demonstrated in the mood disturbances after the stimulations over any of the targets. In conclusion, the application of HF-rTMS over the M1 and SMA significantly improved the motor symptoms in the PD patients but did not alter the mood disturbances.

Efficacy of deep rTMS for neuropathic pain in the lower limb: a randomized, double-blind crossover trial of an H-coil and figure-8 coil.

OBJECTIVE Electrical motor cortex stimulation can relieve neuropathic pain (NP), but its use requires patients to undergo an invasive procedure. Repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex (M1) using a figure-8 coil can relieve NP noninvasively, but its ability to relieve lower limb pain is still limited. Deep rTMS using an H-coil can effectively stimulate deep brain regions and has been widely used for the treatment of various neurological diseases; however, there have been no clinical studies comparing the effectiveness of figure-8 coils and H-coils. This study assessed the clinical effectiveness of 5 once-daily stimulations with H-coils and figure-8 coils in patients with NP. METHODS This randomized, double-blind, 3-way crossover trial examined 18 patients with NP who sequentially received 3 types of stimulations in the M1 for 5 consecutive days; each 5-day stimulation period was followed by a 17-day follow-up period before crossing over to the next type of stimulation. During each rTMS session, patients received a 5-Hz rTMS to the M1 region corresponding to the painful lower limb. The visual analog scale (VAS) and the Japanese version of the short-form McGill Pain Questionnaire 2 (SF-MPQ2-J) were used to measure pain intensity. The primary outcome was VAS score reduction immediately after and 1 hour after intervention. RESULTS Both the VAS and SF-MPQ2-J showed significant pain improvement immediately after deep rTMS with an H-coil as compared with the sham group (p < 0.001 and p = 0.049, respectively). However, neither outcome measure showed significant pain improvement when using a figure-8 coil. The VAS also showed significant pain improvement 1 hour after deep rTMS with an H-coil (p = 0.004) but not 1 hour after rTMS using a figure-8 coil. None of the patients exhibited any serious adverse events. CONCLUSIONS The current findings suggest that the use of deep rTMS with an H-coil in the lower limb region of the M1 in patients with NP was tolerable and could provide significant short-term pain relief. Clinical trial registration no.: UMIN000010536 ( http://www.umin.ac.jp/ctr/ ).

Quantifying Parkinson's disease finger-tapping severity by extracting and synthesizing finger motion properties.

We propose a novel index of Parkinson's disease (PD) finger-tapping severity, called "PDFTsi," for quantifying the severity of symptoms related to the finger tapping of PD patients with high accuracy. To validate the efficacy of PDFTsi, the finger-tapping movements of normal controls and PD patients were measured by using magnetic sensors, and 21 characteristics were extracted from the finger-tapping waveforms. To distinguish motor deterioration due to PD from that due to aging, the aging effect on finger tapping was removed from these characteristics. Principal component analysis (PCA) was applied to the age-normalized characteristics, and principal components that represented the motion properties of finger tapping were calculated. Multiple linear regression (MLR) with stepwise variable selection was applied to the principal components, and PDFTsi was calculated. The calculated PDFTsi indicates that PDFTsi has a high estimation ability, namely a mean square error of 0.45. The estimation ability of PDFTsi is higher than that of the alternative method, MLR with stepwise regression selection without PCA, namely a mean square error of 1.30. This result suggests that PDFTsi can quantify PD finger-tapping severity accurately. Furthermore, the result of interpreting a model for calculating PDFTsi indicated that motion wideness and rhythm disorder are important for estimating PD finger-tapping severity.

Low-frequency subthalamic nucleus stimulation in Parkinson's disease: a randomized clinical trial.

BACKGROUND: Low-frequency, bilateral stimulation of the subthalamic nucleus can improve axial symptoms of advanced Parkinson's disease (PD), but it is not particularly effective for segmental symptoms. METHODS: The optimal contacts for low-frequency (60 Hz) and high-frequency (130 Hz) single monopolar stimulation were determined. Then, in a randomized, double-blind, prospective crossover manner, 60-Hz and 130-Hz stimulations via the respective optimal contacts were compared for immediate efficacy in improving the motor function of patients with PD. RESULTS: The optimal contacts for 60-Hz stimulation were situated more ventrally than those for 130-Hz stimulation (P = 0.038). Under the respective optimal, single monopolar stimulation, 60 Hz provided superior efficacy over 130 Hz in improving the total Unified Parkinson's Disease Rating Scale motor score (P < 0.001) and the akinesia (P = 0.011) and axial motor signs (P = 0.012) subscores without compromising the therapeutic effect on tremor and rigidity. CONCLUSIONS: Low-frequency stimulation via the optimal contacts is effective in improving overall motor function of patients with PD.

Electrical or repetitive transcranial magnetic stimulation of primary motor cortex for intractable neuropathic pain.

OBJECTIVE: To assess the pain-relieving effects of motor cortex electrical stimulation (MCS) and the predictive factors retrospectively. METHODS: Thirty-four patients with intractable neuropathic pain underwent MCS; 19 patients had cerebral lesions, and 15 had non-cerebral lesions. In selected 12 patients, test electrodes were implanted within the central sulcus and on the precentral gyrus. Twelve patients received both MCS and repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex. RESULTS: Pain reduction of >50% was observed in 12 of 32 (36%) patients with >12 months follow-ups (2 patients were excluded because of short follow-up). In 10 of the 12 patients who received test electrodes within the central sulcus and on the precentral gyrus, the optimal stimulation was MCS within the central sulcus. In 4 of these (40%) patients, positive effects were maintained at follow-ups. The pain reduction of rTMS significantly correlated with that of MCS during test stimulation. CONCLUSIONS: The test stimulation within the central sulcus was more effective than that of the precentral gyrus. In the selected patients, chronic stimulation within the central sulcus did not significantly improve long-term results. Repeated rTMS seems to be same effective as MCS.

High-frequency repetitive transcranial magnetic stimulation over the primary foot motor area in Parkinson's disease.

BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) has been reported to be clinically effective for treating motor symptoms in Parkinson's disease (PD). Few studies have been performed reporting the effects of rTMS on non-motor symptoms such as depression and apathy in PD. OBJECTIVE: We assessed the effects of high-frequency (HF) rTMS over the primary motor (M1) foot area on motor symptoms, depression and apathy scales, and sensory symptoms in PD. METHODS: We investigated the efficacy of 3 consecutive days of HF-rTMS over the M1 foot area in 21 patients with PD using a randomized, double-blind cross-over trial compared with sham stimulation. Motor effects were evaluated using the Unified Parkinson's Disease Rating Scale part III (UPDRS-III), the self-assessment motor score, the visual analog scale (VAS), the 10-m walking test, and finger tapping. Non-motor effects were analyzed using the Montgomery Asberg Depression Rating Scale, the Apathy Scale, and quantitative sensory testing. RESULTS: HF-rTMS significantly improved UPDRS-III (P < 0.001), VAS (P < 0.001), the walking test (P = 0.014), self-assessment motor score (P = 0.010), and finger tapping measurement (P < 0.05) compared to sham stimulation. In contrast, no significant improvement was observed in depression and apathy scales. Consecutive days of rTMS did not significantly increase the improvement in motor symptoms. There were no adverse effects following rTMS on patients with PD. CONCLUSIONS: We confirmed that HF-rTMS over the M1 foot area significantly improved motor symptoms in patients with PD. In addition, daily repeated stimulation was not significantly more effective than a single session of stimulation, but may be effective for maintaining the improvement in motor symptoms in patients with PD.

[Risk factors for fractures in Parkinson's disease: a questionnaire survey].

This study investigated the risk factors for fractures in patients with Parkinson's disease (PD). A questionnaire specifically designed to examine these risk factors was mailed to 172 PD patients registered in our self-developed PD database. We subsequently received replies from 158 patients, 22(14.8%)of whom had experienced fractures after PD onset. A multiple logistic regression model was used to evaluate the responses, and together with the clinical information stored in our PD database, it was revealed that psychiatric symptoms and falls within 1 year of our investigation were statistically correlated with the occurrence of fractures (adjusted odds ratio: 4.8 and 3.6, respectively). Thus, these results emphasize that psychiatric symptoms are an essential risk factor for fracture in PD patients.

Parkinsonian rigidity shows variable properties depending on the elbow joint angle.

Parkinsonian rigidity has been thought to be constant through a full range of joint angle. The aim of this study was to perform a detailed investigation of joint angle dependency of rigidity. We first measured muscle tone at the elbow joint in 20 healthy subjects and demonstrated that an angle of approximately 60° of flexion marks the division of two different angle-torque characteristics. Then, we measured muscle tone at the elbow joint in 24 Parkinson's Disease (PD) patients and calculated elastic coefficients in flexion and extension in the ranges of 10°-60° (distal) and 60°-110° (proximal). Rigidity as represented by the elastic coefficient in the distal phase of elbow joint extension was best correlated with the UPDRS rigidity score (r = 0.77). A significant difference between the UPDRS rigidity score 0 group and 1 group was observed in the elastic coefficient in the distal phase of extension (P < 0.0001), whereas no significant difference was observed in the proximal phase of extension and in each phase of flexion. Parkinsonian rigidity shows variable properties depending on the elbow joint angle, and it is clearly detected at the distal phase of elbow extension.

L-threo-3,4-dihydroxyphenylserine (L-DOPS) co-administered with entacapone improves freezing of gait in Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by a variety of motor symptoms including freezing of gait (FOG), in which walking is transiently halted as if the patient's feet were 'glued to the ground'. Treatment of FOG is still challenging. Although L-threo-3,4-dihydroxyphenylserine (L-DOPS), a precursor of noradrenaline, has been on the market in Japan because of its beneficial effect for FOG, clinical use of L-DOPS has been far from satisfying. However, the fact that there were some responders to L-DOPS encouraged us to hypothesize that the enhancement of L-DOPS concentration in the brain by the co-administration of L-DOPS and a catechol-O-methyl transferase (COMT) inhibitor, which is expected to interrupt L-DOPS metabolism in the peripheral circulation, would be beneficial for FOG. Based on our hypothesis, we conducted a preliminary study with a small number of participants with FOG. Of the 16 PD patients with FOG who completed this study, group 1 (n=6) received L-DOPS co-administered with entacapone, which is a COMT inhibitor used worldwide as an anti-parkinson drug, group 2 (n=5) received entacapone alone, and group 3 (n=5) received L-DOPS alone. Only the patients in group 1 showed a significant improvement in FOG. Moreover, the beneficial effect was observed only in patients with levodopa-resistant FOG. This result supports our hypothesis, at least in patients with levodopa-resistant FOG, and shows that the co-administration of L-DOPS and entacapone could be a new strategy for FOG treatment.

Noisy interlimb coordination can be a main cause of freezing of gait in patients with little to no parkinsonism.

Freezing of gait in patients with Parkinson's disease is associated with several factors, including interlimb incoordination and impaired gait cycle regulation. Gait analysis in patients with Parkinson's disease is confounded by parkinsonian symptoms such as rigidity. To understand the mechanisms underlying freezing of gait, we compared gait patterns during straight walking between 9 patients with freezing of gait but little to no parkinsonism (freezing patients) and 11 patients with Parkinson's disease (non-freezing patients). Wireless sensors were used to detect foot contact and toe-off events, and the step phase of each foot contact was calculated by defining one stride cycle of the other leg as 360°. Phase-resetting analysis was performed, whereby the relation between the step phase of one leg and the subsequent phase change in the following step of the other leg was quantified using regression analysis. A small slope of the regression line indicates a forceful correction (phase reset) at every step of the deviation of step phase from the equilibrium phase, usually at around 180°. The slope of this relation was smaller in freezing patients than in non-freezing patients, but the slope exhibited larger step-to-step variability. This indicates that freezing patients executed a forceful but noisy correction of the deviation of step phase, whereas non-freezing patients made a gradual correction of the deviation. Moreover, freezing patients tended to show more variable step phase and stride time than non-freezing patients. Dynamics of a model of two coupled oscillators interacting through a phase resetting mechanism were examined, and indicated that the deterioration of phase reset by noise provoked variability in step phase and stride time. That is, interlimb coordination can affect regulation of the gait cycle. These results suggest that noisy interlimb coordination, which probably caused forceful corrections of step phase deviation, can be a cause of freezing of gait.

Severity estimation of finger-tapping caused by Parkinson's disease by using linear discriminant regression analysis.

We propose a linear discriminant regression analysis (LDRA) that provides an estimated severity marker for discriminating between healthy and patient groups and estimating severities of the patient group simultaneously. This method combines an evaluation function for discriminating between two groups and one for estimating severities of one group. The combined function is optimized to obtain an equation for calculating estimated severities. The method was evaluated with finger-tapping data of healthy and Parkinson's disease (PD) groups and PD severities assessed by a doctor. As a result, the discrimination ability of LDRA (AUC: 0.8835) was higher than that of discriminant analysis (DA. AUC: 0.8442), which is a conventional method for classification, and the regression ability of LDRA (mean square error (MSE): 1.27) was superior to that of multiple regression analysis (MRA. MSE: 1.68), which is a conventional method for regression. The results show that LDRA is an effective method for estimating the presence and severity of Parkinson's disease.

Psychometrics of dominant right hand during the 9-hole PEG test: differences between PEG placement and removal.

OBJECTIVE: To assess psychometrics of hand dominance during the 9-Hole Peg Test. SUBJECTS: Sixteen healthy volunteers (23-40 years of age, 10 female and 6 male subjects, all fortuitously right handed). METHODS: As is conventional protocol, the total time to perform the task was recorded as a dexterity index. In addition, the relative distance between points (distal phalanges) on the index finger and thumb was continuously monitored by the use of a magnetic sensing system. Time required, mean values for peak distance, and cumulative total motion distance were analyzed separately for the peg-placement and peg-removal phases. Data for dominant and nondominant hands were compared by the use of paired t-tests (P < .05). RESULTS: Total time to perform the 9-Hole Peg Test was shorter for the dominant hands (mean, 18.65 seconds) than the nondominant hands (mean, 20.11 seconds). During the peg-placement phase, lower values for peak distance, cumulative total motion distance, and time required were recorded for dominant hands, suggesting more efficient movement. By contrast, during peg-removal phase, no statistically significant differences between dominant- and nondominant-hand values were apparent. CONCLUSIONS: Although healthy subjects perform the 9-Hole Peg Test more efficiently using their dominant hands, the difference in measured dexterity was observed only during the peg-placement phase. This discrepancy between the peg-placement and peg-removal efficiency suggests the need for phase discrimination in future studies.

Estimation method of finger tapping dynamics using simple magnetic detection system.

We have developed the simple estimation method of a finger tapping dynamics model for investigating muscle resistance and stiffness during tapping movement in normal subjects. We measured finger tapping movements of 207 normal subjects using a magnetic finger tapping detection system. Each subject tapped two fingers in time with a metronome at 1, 2, 3, 4, and 5 Hz. The velocity and acceleration values for both the closing and opening tapping data were used to estimate a finger tapping dynamics model. Using the frequency response of the ratio of acceleration to velocity of the mechanical impedance parameters, we estimated the resistance (friction coefficient) and compliance (stiffness). We found two dynamics models for the maximum open position and tap position. In the maximum open position, the extensor muscle resistance was twice as high as the flexor muscle resistance and males had a higher spring constant. In the tap position, the flexor muscle resistance was much higher than the extensor muscle resistance. This indicates that the tapping dynamics in the maximum open position are controlled by the balance of extensor and flexor muscle friction resistances and the flexor stiffness, and the flexor friction resistance is the main component in the tap position. It can be concluded that our estimation method makes it possible to understand the tapping dynamics.