Hiroo Ichikawa

Effect of motion imagery to counter rest-induced suppression of F-wave as a measure of anterior horn cell excitability

OBJECTIVE To test if motor imagery prevents the rest-induced suppression of anterior horn cell excitability. METHODS Ten healthy subjects underwent two separate experiments, each consisting of stimulating the median nerve 100 times and recording F-waves from abductor pollicis brevis (APB) in three consecutive sessions: (1) after muscle exercise to standardize the baseline, (2) after immobilization of APB for 3h and (3) after muscle exercise to check recovery. We instructed the subject to volitionally relax APB in experiment 1 (relaxation task), and to periodically simulate thumb abduction without actual movement in experiment 2 (imagery task). RESULTS F-wave persistence and amplitude declined after relaxation task and recovered quickly after exercise, but changed little with imagery task. F-wave latencies showed no change when analyzed individually. The frequency distribution of collective F-waves recorded from all subjects remained the same after relaxation task, but showed a shift toward longer latencies after imagery task. CONCLUSIONS Mental imagery without overt motor output suffices to counter the effect of sustained volitional muscle relaxation, which would, otherwise, cause a reversible reduction in anterior horn cell excitability. SIGNIFICANCE This finding documents the importance of central drive for spinal excitability, which affects F-wave studies of a paretic muscle.

Writing errors and anosognosia in amyotrophic lateral sclerosis with dementia

Amyotrophic lateral sclerosis (ALS) with dementia (ALS-D) is known to exhibit characteristics of frontotemporal dementia. However, in clinical situations, it is often difficult to evaluate their cognitive functions because of impaired voluntary speech and physical disabilities. In order to identify characteristic and diagnostic cognitive symptoms of relatively advanced ALS-D patients, we retrospectively reviewed the clinical features of seven cases of clinically definitive ALS who had dementia, impaired voluntary speech, and physical disability. Their medical records showed that six out of seven patients made writing errors, and all of the patients demonstrated anosognosia. The writing errors consisted of paragraphia such as substitution, omission, or syntactic errors with individual differences in error types. Dissociation between kana and kanji were also observed. Anosognosia was evaluated by a self-rating scale with which the patients and the medical staff evaluated the patients physical ability; the results indicated a large discrepancy between the evaluation by the patients and the medical staff. We emphasize that aphasic writing errors have been underestimated, particularly in ALS-D patients with impaired voluntary speech. We also reported that anosognosia was the most important and quantifiable symptom in ALS-D. The relationship between writing errors and anosognosia should be investigated further.

Agraphia in Bulbar-Onset Amyotrophic Lateral Sclerosis: Not Merely a Consequence of Dementia or Aphasia

The clinical significance and characteristics of writing errors in bulbar-onset amyotrophic lateral sclerosis (ALS) are not clear. We retrospectively investigated writing samples in 19 patients with bulbar-onset ALS without preceding extra-motor symptoms. Co-development of dementia and/or aphasia was also explored and single photon emission computed tomography (SPECT) images of the brain were reviewed. As a result, a high prevalence of writing errors (15 of the 19 patients) was found. Of note were isolated writing errors with neither dementia nor aphasia verified in 2 patients whose dysarthria was mild enough to evaluate spoken language. The remaining 13 patients also showed agraphia, but either dysarthria was too severe to evaluate aphasia or frontotemporal dementia (FTD)-like features co-existed. Of these patients, one who initially lacked dementia subsequently developed FTD-like features. The frequent writing errors were omission or substitution of kana letters and syntactic errors. SPECT images showed bilateral or left-side dominant hypoperfusion in the frontotemporal lobes as a consistent feature. These results show that patients with bulbar-onset ALS frequently exhibit agraphic writing errors and that these are not merely consequences of dementia or aphasia. However, these writing errors may indicate the involvement of frontotemporal language-related areas beyond the primary motor cortex.

Unilateral oculomotor nerve palsy associated with anti-GQ1b IgG antibody

We describe a patient with acute unilateral oculomotor nerve palsy that occurred after an upper respiratory infection. His serum showed a high titer of anti-GQ1b IgG antibody during the acute phase of the illness, suggesting a possible postinfectious immune-mediated mechanism. A previously healthy, 47-year-old man developed diplopia (day 1) 2 weeks after experiencing a fever and cough. On admission (day 12), his blood pressure was 110/70 mm Hg, his pulse rate was 78 beats per minute, and his body temperature was 36.5 °C. Neurologic examination revealed blepharoptosis and limitation of adduction and vertical gaze on the left side (figure). Convergence was impossible. Although both pupils were symmetric (4 mm) and promptly reactive to light, pupillometry revealed a delayed reaction to light in the left pupil (data not shown). These findings were compatible with left oculomotor nerve palsy. The other cranial nerves were intact. His gait was normal, and no muscle weakness, ataxia, or sensory …

Effect of motor imagery and voluntary muscle contraction on the F wave.

We tested the validity of instructing patients to minimally contract the muscle to facilitate F‐wave recording in clinical practice. In 12 healthy subjects, F waves were recorded from the first dorsal interosseous muscle at rest, during motor imagery, and at up to 30% of the maximal voluntary contraction (MVC). F‐wave persistence increased significantly from 32.5 ± 11.9% (mean ± SD) at rest to 58.3 ± 15.2% during motor imagery and 90.0 ± 8.7% during 3% MVC. It then remained the same during stepwise changes to and from 30% MVC before decreasing significantly from 80.8 ± 18.5% during 3% MVC to 48.7 ± 23.8% during motor imagery and 27.0 ± 16.0% at rest. The trial average of F‐wave amplitude showed a similar pattern of facilitation. Motor imagery enhances F‐wave persistence and amplitude, which further increase with a slight muscle contraction and show no additional change with a stronger effort. Muscle Nerve, 2010

Occurrence and Clinicotopographical Correlates of Brainstem Infarction in Patients with Diabetes Mellitus

BACKGROUND The goal of the study was to clarify the association between diabetes mellitus (DM) and brainstem infarctions (BSIs) and to investigate the clinicotopographic characteristics of BSIs in patients with diabetes. METHODS Data were retrospectively reviewed for 1026 consecutive patients admitted to our hospital because of acute cerebral infarctions from January 2004 to August 2010. Acute symptomatic BSIs were explored on radiologic images and classified into multiple infarctions with BSIs, multifocal BSIs, and monofocal BSIs. Isolated BSIs were further classified based on the vertical distribution into midbrain, pontine, and medullary infarctions, and on the horizontal distribution into anterior-dominant, posterior-dominant, and anterior/posterior BSIs. Neurologic symptoms of BSIs and clinical background were compared between DM and non-DM patients. RESULTS The prevalence of BSIs was 2.6-fold higher (P < .0001) in DM patients. Logistic regression analysis including age, sex, smoking, previous stroke, atrial fibrillation, other cardiac diseases, hypertension, hyperlipidemia, and DM showed that DM was independently associated with BSIs (odds ratio [OR] 2.814; 95% confidence interval [CI] 1.936-4.090; P < .0001). Compared with non-DM patients, DM patients showed more frequent monofocal BSIs (P < .0001) and multifocal BSIs (P = .0296). Monofocal BSIs (n = 114) more frequently involved the pons (P < .0001) and medulla (P = .0212). Anterior-dominant BSIs (P < .0001) were more common in DM patients than in non-DM patients. Symptoms of BSIs included more frequent motor paresis (P = .0180) and less frequent diplopia (P = .0298) in DM patients than in non-DM patients. CONCLUSIONS DM is important in the development of BSIs, and the associated clinical characteristics include more frequent motor paresis and less frequent diplopia.

Effect of volitional relaxation and motor imagery on F wave and MEP: do these tasks affect excitability of the spinal or cortical motor neurons?

OBJECTIVE To test if simple motor imagery, like thumb abduction, preferentially influences the excitability of the spinal or cortical motoneurons. METHODS Ten healthy subjects underwent two separate experiments, each consisting of recording F waves and MEPs from abductor pollicis brevis (APB) in three consecutive sessions: (1) baseline, (2) after immobilizing APB for 3 h, and (3) after brief muscle exercise. During the immobilization, the subjects were instructed to volitionally relax APB in experiment 1 (relaxation task), and mentally simulate thumb abduction without actual movement in experiment 2 (imagery task). RESULTS Relaxation task suppressed both MEPs and F waves. Motor imagery reduced this suppression, restoring F waves nearly completely (94%) and MEPs only partially (77%). Hence, the rest-induced decline of MEPs in part results from cortical modulation. In contrast, statistical analysis revealed no differences in imagery-induced recovery of motoneuron excitabilities whether assessed by F wave or MEP. Thus, increased excitability of spinal motoneurons responsible for F-wave changes also accounts for recovery of MEPs. CONCLUSIONS Volitional relaxation depresses the spinal and cortical motoneurons, whereas mental simulation counters rest-induced suppression primarily by restoring spinal excitability. SIGNIFICANCE The present findings help elucidate physiologic mechanisms underlying motor imagery.

Dilative arterial remodeling of the brain with different effects on the anterior and posterior circulation: An MRI study

OBJECTIVE The goal of the study was to investigate factors associated with dilation of the internal carotid artery (ICA) and basilar artery (BA), which reflect the anterior and posterior circulation respectively, and to examine if these arteries are affected differently by specific factors. METHODS The diameters of ICA and BA were measured using T2-weighted magnetic resonance (MR) images at the level of the brainstem in 304 outpatients, with the maximal width of the flow void taken as the diameter for each artery. The association between the diameters and clinical data including hemoglobin A1c (HbA1c) and estimated glomerular filtration rate (eGFR) was investigated. The same analysis was performed for the BA/ICA ratio. RESULTS Multiple regression analysis adjusted for confounding factors including gender and age showed that a lower eGFR was independently associated with dilation of both the ICA (beta coefficient -0.148, P=0.0135) and the BA (beta -0.219, P=0.0007). HbA1C was independently associated with a greater BA/ICA ratio (beta -0.183, P=0.0015) but eGFR did not show this association. Diabetes mellitus was significantly more frequent (P=0.0353) in patients with a BA/ICA ratio higher than the mean, compared to those with a lower BA/ICA ratio. CONCLUSION Kidney dysfunction was shown to be a dilative factor for the anterior and posterior circulation as reflected by the ICA and BA diameters, respectively. The association of the BA/ICA ratio with HbA1c suggests that diabetes mellitus may affect each circulation differently.

An autopsied case of Sjogren's syndrome with massive necrotic and demyelinating lesions of the cerebellar white matter.

A 69-year-old woman developed subacute cerebellar ataxia and tremors in all four limbs in April 1996. Laboratory examination showed elevated antibodies against Ro and La. Head magnetic resonance imaging showed T(2) high-intensity lesions in the cerebellar white matter bilaterally and later in the pons. In April 2000, she died of multiple organ failure with incidental colon cancer. The autopsy showed atrophic parotid glands with an accumulation of lymphocytes around the ducts, confirming the diagnosis of Sjogrens syndrome histopathologically. The neuropathological examination revealed severe necrotic lesions in the cerebellar white matter bilaterally with several foci of perivenous demyelination in the periphery of the lesions and similar demyelinated areas in the pons. Immunohistochemistry with anti-JC virus antibody demonstrated no positive inclusions. A single focus of granulomatous arteritis was observed in one subarachnoid artery. The combination of Sjogrens syndrome, granulomatous angitis, and foci of perivenous demyelination suggests that an autoimmune mechanism played an important role in causing the necrotic lesions in the cerebellar white matter in this case.

Kana versus Kanji in Amyotrophic Lateral Sclerosis: A Clinicoradiological Study of Writing Errors

The frequency of writing errors in samples from 14 patients with amyotrophic lateral sclerosis without manifest aphasia were compared with clinical background and indices from X-ray computed tomography, including the Evans’ index (EI) and the cella media index (CMI). The inferior horn index (IHI) was measured as the maximal width of the short axis of the bilateral inferior horn of the lateral ventricles/the maximum transverse distance between the two internal laminae. Overt dementia and disinhibitive behavioral changes were significantly associated with frequency of total errors (p = 0.0280) and kanji errors (p = 0.0025). Significant associations were found for the EI with kana errors (p = 0.0481) and for the IHI with kanji errors (p = 0.0052). Preferential involvement of kana and kanji may reflect involvement of language-related areas in the frontotemporal lobes with frontal lobe or temporal lobe predominance.