Bram W. Ongerboer de Visser

Blink reflex recovery curves in blepharospasm, torticollis spasmodica, and hemifacial spasm.

R1 and R2 blink reflex responses to single and paired stimuli were investigated in 23 control subjects: 21 patients with blepharospasm (BSP), 20 patients with torticollis spasmodica (TS), and 23 with hemifacial spasm (HFS). For paired stimuli, we compared measurements of area and peak responses at two and three times R2 threshold. R1 and R2 indices were calculated as the average of the recovery values at 0.5‐, 0.3‐, and 0.21‐s interstimulus intervals to test individual patients. Peak amplitude measurements at three times R2 threshold were optimal. The R2 index was abnormal in 67% of BSP patients, 37% of TS patients, and 50% of HFS patients on the affected side and 20% on the unaffected side. A normal R2 index in one third of patients with BSP may indicate that different pathophysiological mechanisms are involved in this type of focal dystonia.

Predicting Survival in Patients with Early Alzheimer’s Disease

We investigated whether an index based on clinical features, electroencephalogram and computed tomography is useful to predict survival in early Alzheimer’s disease. One hundred and sixty-three consecutively referred patients to an outpatient memory clinic and first diagnosed with Alzheimer’s disease (105 ‘probable’ and 58 ‘possible’, NINCDS-ADRDA criteria) were studied and outcome measure was death. Cox proportional hazards regression analysis and Kaplan-Meier survival curves were used to investigate relations between baseline parameters and survival. Eighty-four patients (51.5%) died during the follow-up period that extended to 5.8 years, with a median duration of survival after entry of 4.3 years. Baseline factors that were statistically significant and independently related to increased risk of mortality were high age, male sex, poor cognitive function as measured with the CAMCOG, low alpha and beta power on electroencephalogram, and temporoparietal atrophy on computed tomography scan. These results were independent of the diagnosis probable or possible Alzheimer’s disease. Based on the coefficients from the regression equation, we computed a survival index for each patient and we constructed three groups according to tertiles of this index. After 5.2 years of follow-up, survival curves showed a low mortality group with 81.7% patients alive (median survival at least 5.7 years), an intermediate mortality group with 35.9% patients alive (median survival 3.8 years), and a high mortality group with no patients alive (median survival 2.3 years). Log rank tests were statistically significant for comparisons between all three groups. We conclude that an overall index combining demographic, cognitive, electroencephalogram and computed tomography features is a strong predictor of survival in early Alzheimer’s disease.

Spectral analysis of the EEG and 99m-Tc-HMPAO SPECT-scan in Alzheimer's disease

99m-technetium-hexamethylpropylene-amineoxine (99m-Tc-HMPAO) single-photon-emission-computer-tomography (SPECT)-scans and spectral analyzed electroencephalogram (EEGs) of 20 patients with Alzheimers disease (AD) were studied. A significant correlation was found between the temporoparietal-cerebellar-ratio (TP/C-ratio) of the SPECT-scan and the peak frequencies of leads T3-T5, C3-P3, and C4-P4 of the EEG. In addition a significant negative correlation between the TP/C-ratio and the theta/alpha-ratio (t/a-ratio) of leads T3-T5, T4-T6, C3-P3, and C4-P4 was demonstrated. Our study demonstrates that slowing of the EEG parallels a decrease in blood flow in the temporoparietal regions in AD-patients. Both findings could be parallel phenomena of regional hypometabolism.

Evidence for recurrent laryngeal nerve contribution in motor innervation of the human cricopharyngeal muscle

Objective: To study the functional motor nerve supply of the upper esophageal sphincter in humans. Study Design: Intraoperative electromyographic study. Methods: The contribution of the recurrent laryngeal nerve and the pharyngeal plexus in the motor nerve innervation of the cricopharyngeal muscle and the inferior pharyngeal constrictor muscle was examined intraoperatively. Results: Electromyography showed that there is a considerable overlap in the innervation of the cricopharyngeal muscle and the inferior pharyngeal constrictor muscle. The recurrent laryngeal nerve functionally contributes to the motor innervation of the cricopharyngeal muscle in all patients and contributes to the motor innervation of the inferior pharyngeal constrictor muscle in most patients. The pharyngeal plexus functionally contributes to the motor innervation of the inferior pharyngeal constrictor muscle but does not always contribute to the motor innervation of the cricopharyngeal muscle. Conclusions: This is the first report which provides evidence that the recurrent laryngeal nerve functionally contributes to the motor innervation of the cricopharyngeal and inferior pharyngeal constrictor muscle. Furthermore, this study shows that intraoperative electromyography in humans is a feasible method to analyze the physiology of the motor innervation of the upper esophageal sphincter.

A retrograde double fluorescent tracing study of the levator palpebrae superioris muscle in the cynomolgus monkey

In the cynomolgus monkey, motoneurons innervating the levator palpebrae superioris muscle form a nucleus within the oculomotor nuclei called the central caudal nucleus. After double fluorescent neuronal retrograde tracing experiments, using fast blue and diamidino yellow as tracers in the levator palpebrae superior muscles, labelled motoneurons (30%) were found in an unpaired central caudal nucleus. Approximately 2% of the labelled motoneurons were double-labelled. The labelled and double-labelled neurons were distributed randomly over the central caudal nucleus, lateralization of populations of levator motoneurons within this nucleus was not observed. The afferent innervation of the levator palpebrae superioris muscle was restricted to the ophthalmic branch area of the gasserian ganglion. Primary afferent labelled neurons were absent from mesencephalic nucleus of the fifth nerve. Surprisingly, fast blue was also found in the ophthalmic branch area of the contralateral ganglion of Gasser, while diamidino yellow was present only ipsilaterally. About 1% of the afferent labelled neurons were double-labelled. The results reveal that in the cynomolgus monkey the central caudal nucleus is not only topographically but also functionally one nucleus. Afferent innervation of the levator palpebrae superioris muscle is probably bilaterally organized.

A Comparison of Myogenic Motor Evoked Responses to Electrical and Magnetic Transcranial Stimulation During Nitrous Oxide/opioid Anesthesia

UNLABELLED Transcranial motor evoked potentials (tc-MEPs) are used to monitor spinal cord integrity intraoperatively. We compared myogenic motor evoked responses with electrical and magnetic transcranial stimuli during nitrous oxide/opioid anesthesia. In 11 patients undergoing spinal surgery, anesthesia was induced with i.v. etomidate 0.3 mg/kg and sufentanil 1.5 microg/kg and was maintained with sufentanil 0.5 microg x kg(-1) x h(-1) and N2O 50% in oxygen. Muscle relaxation was kept at 25% of control with i.v. vecuronium. Electrical stimulation was accomplished with a transcranial stimulator set at maximal output (1200 V). Magnetic transcranial stimulation was accomplished with a transcranial stimulator set at maximal output (2 T). Just before skin incision, triplicate responses to single stimuli with both modes of cortical stimulation were randomly recorded from the tibialis anterior muscles. Amplitudes and latencies were compared using the Wilcoxon signed rank test. Bilateral tc-MEP responses were obtained in every patient with electrical stimulation. Magnetic stimulation evoked only unilateral responses in two patients. With electrical stimulation, the median tc-MEP amplitude was 401 microV (range 145-1145 microV), and latency was 32.8 +/- 2.3 ms. With magnetic stimulation, the tc-MEP amplitude was 287 microV (range 64-506 microV) (P < 0.05), and the latency was 34.7 +/- 2.1 ms (P < 0.05). We conclude that myogenic responses to magnetic transcranial stimulation are more sensitive to anesthetic-induced motoneural depression compared with those elicited by electrical transcranial stimulation. IMPLICATIONS Transcranial motor evoked potentials are used to monitor spinal cord integrity intraoperatively. We compared the relative efficacy of electrical and magnetic transcranial stimuli in anesthetized patients. It seems that myogenic responses to magnetic transcranial stimulation are more sensitive to anesthetic-induced motoneural depression compared with electrical transcranial stimulation.

Retrograde tracing studies of subdivisions of the orbicularis oculi muscle in the rhesus monkey

Abstract Functionally and anatomically, the orbicularis oculi (OO) muscle can be subdivided in a pretarsal, a preseptal, and an orbital portion. In the rhesus monkey, fluorescent and neuronal retrograde tracing experiments were performed in the pretarsal or the orbital portion of the OO muscle, or both, using fast blue, diamidino yellow, and wheat germ agglutinin-horseradish peroxidase as tracers. The preseptal portion was not investigated because of close anatomical relationships to the other portions. It was found that motoneurons innervating the OO muscle are located exclusively within the intermediate subnucleus of the motor facial nucleus. The upper pretarsal motoneurons show a specific distribution in the dorso-rostral border area of the intermediate subnucleus, representing a dome-like organization, while lower pretarsal motoneurons are situated more ventrally in the adjacent area. The pretarsal motoneurons are all located dorsally in the rostral half and the upper part of the caudal half of the intermediate subnucleus. The upper pretarsal portion is subserved by about one third of the total intermediate motoneuron population. The size of the upper pretarsal motoneurons is similar to that of the motoneurons of the lower pretarsal portion of the OO muscle and falls, for the vast majority, into the large motoneuronal range. Motoneurons belonging to the upper and lower orbital portions are located ventrally and are more randomly distributed in the rostral half of the intermediate subnucleus. The size of orbital motoneurons varies from small to large. The large fraction of pretarsal motoneurons may reflect the specific function of the upper pretarsal portion during rapid and highly coordinated movements of the eyelids in different types of blinking.

Muscle strength in postpolio patients : A prospective follow-up study

Forty‐three former polio patients now complaining of new progressive muscle weakness (symptomatic patients) plus 13 former polio patients without new neuromuscular complaints were included in the study. The symptomatic patients reported high frequencies of other neuromuscular complaints and a decline in their functional level. Most frequent complaints were general fatigue, low backache, and muscle pain (97.7%, 86%, and 79.1%, respectively) and a decline in the ability to walk (80%). In a prospective follow‐up averaging 2.1 years, the muscle strength of 26 muscles in all four limbs of each patient was assessed by manual muscle testing and was also measured isometrically using a handheld dynamometer. During the follow‐up period, we did not find a significant decrease in muscle strength in the symptomatic patients as compared to patients without new neuromuscular complaints.

Origin of eye and eyelid movements during blinking

Studies of blinks have revealed the reciprocal relation-ship between innervation patterns of the levator palpe-brae superioris (LP) and the orbicularis oculi (OO)muscles, resulting in a downward movement of the uppereyelid. Immediately before a blink, tonic activity of LPceases followed by OO muscle activity. At the end of ablink, OO actively turns off and LP returns to its previ-ous tonic activity either accompanied by an initial burstor not.

Macro EMG follow-up study in post-poliomyelitis patients

We investigated the muscle strength and motor unit (MU) territory of five patients with postpolio syndrome (PPS), six stable patients with prior poliomyelitis, and five healthy volunteers. The MU territory was assessed by measuring amplitudes of motor unit potentials (MUPs) recorded by the macro EMG technique. The investigations were repeated after 11–20 months (mean 15.6). The macro MUP amplitudes in both patient groups were markedly increased (P = 0.02). However, no statistical difference was found between the two groups in the initial amplitude values. Macro MUP amplitudes obtained on repeated examinations did not differ significantly from the initial macro MUP amplitudes in any of the three groups. In three individual PPS patients, a decline in muscle strength on the follow-up study was documented, providing the diagnosis of post-poliomyelitis muscular atrophy (PPMA). The three PPMA patients had the highest initial macro MUPs. Two of them showed a decrease in macro MUP amplitudes on follow-up. These findings suggest that a later breakdown of oversized MUs may play a role in the pathogenesis of PPMA.