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H C Hopf

Publications and source records attributed to H C Hopf.

At least 19 recordsLinked to original sources
PubMed1992

[Localization of level of lesions in internuclear ophthalmoplegia through assessment of masseter and blink reflex].

The masseter and blink reflexes were investigated in 100 patients with internuclear ophthalmoplegia due to multiple sclerosis (58 patients) or lacunar brainstem infarction (42 patients). In unilateral internuclear ophthalmoplegia, 38 of 60 patients (63.3%) had masseter reflex abnormalities, two patients (3.3%) showed changes of the blink reflex R1 component, and 13 patients (21.7%) combined alterations of the masseter reflex and the blink reflex R1 component. 46 (86.8%) of these 53 patients with electrophysiological abnormalities had unilateral changes, which were ipsilateral to the medial longitudinal fasciculus lesion in 42 patients (91.3%). In bilateral internuclear ophthalmoplegia, 24 of 40 patients (60.0%) had abnormalities of the masseter reflex, two (5.0%) showed changes of the blink reflex R1, and nine (22.5%) combined alterations of the masseter reflex and the blink reflex R1 component. 20 (57.1%) of these 35 patients with electrophysiological abnormalities had bilateral changes. Thus, masseter reflex abnormalities indicating midbrain lesions were seen in 63.3% and 60.0%, respectively, of unilateral and bilateral internuclear ophthalmoplegia. Blink reflex R1 component changes with or without impairment of the masseter reflex indicating rostral pontine to midpontine lesions occurred in 25.0% and 27.5%, respectively. These figures correspond to the results of postmortem examinations and to theoretical considerations based on the length of the medial longitudinal fasciculus.

Adult↗
PubMed1992

Impaired neuromuscular transmission during partial inhibition of acetylcholinesterase: the role of stimulus-induced antidromic backfiring in the generation of the decrement-increment phenomenon.

Neuromuscular transmission was studied in the rat phrenic nerve-hemidiaphragm preparation with acetylcholinesterase (AChE) partially inactivated. Enzyme inhibition resulted in (1) increased single-twitch tension of the diaphragm; (2) compound muscle action potential (CMAP) containing repetitive discharges; (3) stimulus-induced antidromic backfiring (SIAB) seen in the phrenic nerve; and (4) repetitive nerve stimulation (RNS) eliciting a decrement-increment (D-I) phenomenon (i.e., amplitude reduction maximal with the second CMAP). Using a high-calcium and low-magnesium solution, SIAB and the decrement of the second CMAP during RNS were intensified, whereas closely spaced trains and (+)-tubocurarine (TC) abolished SIAB and simultaneously prevented the decrement of the second CMAP. Importantly, low concentrations of (+)-TC prevented SIAB in the phrenic nerve, while the repetitive discharges of the CMAP and the increase in twitch tension remained unaffected. This observation suggests that preterminal nicotinic receptors stimulated by released acetylcholine induce SIAB, whereas postsynaptic events are less important in the generation of SIAB. SIAB, a presynaptic event, appears to be responsible for the transient impairment of the neuromuscular transmission, i.e., the D-I phenomenon.

Acetylcholinesterase↗
PubMed1992

The pterygoid reflex in man and its clinical application.

A technique for eliciting and recording the stretch reflex (R) of the medial pterygoid muscle (Pter) is described. The latency was 6.9 +/- 0.43 ms in 23 healthy volunteers (mean age 23.7 years) showing a side-to-side difference of 0.29 +/- 0.21 ms. The PterR latencies were little shorter and side-to-side differences little greater than of the masseter reflex. Observations in 5 selected patients with small brainstem lesions suggest that the neurons of the PterR afferents form a cluster within the caudal portion of the trigeminal mesencephalic nucleus. Testing the masseter and pterygoid reflexes provides a more precise localization of small ponto-mesencephalic lesions.

Adult↗
PubMed1992

Acquired monocular elevation paresis. An asymmetric upgaze palsy.

Five patients with acquired monocular elevation paresis were investigated using direct current electroculography. With recovery, upward saccade velocities significantly increased in both eyes in all patients. The gain of upward-following eye movements significantly increased in the paretic eye of all patients and in the opposite eye of four patients. These findings are interpreted in terms of an asymmetric upgaze palsy which clinically presented as monocular elevation paresis in the more severely affected eye. A brainstem lesion contralateral to monocular elevation paresis was suggested in four patients by contralateral Horner's syndrome and contralateral abduction paresis, each in one patient, and contralateral ptosis in two patients. In only one patient, computerized tomography and magnetic resonance imaging substantiated a contralateral meso-diencephalic lesion.

Adult↗
PubMed1992

Cerebral potentials elicited by mechanical stimuli to the human leg: influence of artifacts.

Mechanical stimulation with a reflex hammer was applied to the quadriceps muscle tendon of healthy volunteers and patients. The time-locked electrical signals were recorded from the scalp. In all cases, reproducible potentials could be recorded, with latencies in a range of 20 ms to 100 ms. The potentials recorded in patients under complete spinal anesthesia were similar to those derived before the anesthesia. In brain dead patients who showed absence of median nerve or posterior tibial nerve SEP, reproducible potentials after mechanical stimuli could be recorded as well. The results suggest that the hammer taps lead to mechanical shock waves which are propagated along the body producing time locked artifacts in the EEG record which are not eliminated by the averaging technique.

Adult↗
PubMed1992

Abduction nystagmus in internuclear ophthalmoplegia.

Direct current electro-oculography revealed abduction nystagmus with hypermetric abduction saccades in 35 of 64 patients with unilateral and 55 of 66 patients with bilateral internuclear ophthalmoplegia. Slowing of abduction saccades occurred in 27 unilateral cases, mainly ipsilateral to the paretic eye, and in 36 bilateral cases. Abduction nystagmus with hypermetric abduction saccades of normal velocity is explained by an increased phasic innervation adjusted to adduction paresis. Slowed abduction saccades are attributed to impaired inhibition of the medial rectus muscle. Superposition of impaired medial rectus inhibition and increased phasic innervation best explains abduction nystagmus with slowed hypermetric (6 unilateral and 23 bilateral cases) or normometric abduction saccades (9 unilateral and 5 bilateral cases).

Adult↗
PubMed1992

Internuclear ophthalmoplegia of abduction: clinical and electrophysiological data on the existence of an abduction paresis of prenuclear origin.

Three patients showed unilateral and five bilateral abduction paresis. Five had associated adduction nystagmus of the contralateral eye. Electrophysiological testing of masseter and blink reflexes indicated an ipsilateral rostral pontine or mesencephalic lesion, and excluded a lesion of the infranuclear portion of the abducens nerve. Abduction paresis was attributed to impaired inhibition of the tonic resting activity of the antagonistic medial rectus muscle. The prenuclear origin of the disorder is based on morphological and neurophysiological evidence of an ipsilateral inhibitory connection between the paramedian pontine reticular formation and the oculomotor nucleus running close to but separated from the medial longitudinal fasciculus.

Abducens Nerve↗
PubMed1992

Localization of emotional and volitional facial paresis.

Emotional facial paresis is characterized by impaired activation of face muscles with emotion but normal voluntary activation. We report seven patients with this sign. Their lesions involved the frontal lobe white matter, the striatocapsular territory, the anterolateral thalamus and insula, the posterior thalamus and operculum, and the mesial temporal lobe and insula each in one patient, and the posterior thalamus in two patients. Volitional facial paresis affects facial movements with voluntary effort, sparing activation on emotion. We report four such patients, with lesions involving the motor cortex in one and the pyramidal tract in the cerebral hemisphere in three.

Adult↗
PubMed1992

Persistent unilateral tibialis anterior muscle hypertrophy with complex repetitive discharges and myalgia: report of two unique cases and response to botulinum toxin.

Unilateral enlargement of the tibialis anterior muscle associated with complex repetitive discharges occurred over several months in two patients and was preceded by pain and numbness in the lower leg. Neuroradiologic investigations excluded a compressive radiculopathy, but pharmacologic and neurophysiologic studies suggested a neurogenic basis for the muscle hypertrophy. Botulinum toxin A injection into the hypertrophied muscles led to a decreased muscle volume and cessation of muscle pain.

Adult↗
PubMed1992

[Pauses in masseter innervation (silent periods) following stimulation of the median nerve, the cervical plexus and the mental nerve].

In 20 healthy volunteers, a bilateral masseter silent period (Mass SP) was constantly evoked by stimulating the mental nerve (latency: x = 13.95 +/- 4.3 ms) and cervical plexus (latency: x = 20.2 +/- 3.7 ms). This was also the case with median nerve stimulation (latency: x = 54.4 +/- 13.1 ms) in 19 of the 20 subjects. Utilizing magnetic stimulation of the lumbal roots, the Mass SP was elicited in 3 of 10 subjects and showed marked habituation. No Mass SP was observed with stimulation of the long nerves of the lower limbs. The central loop of the reflex represents a stable connection between the spinal cord cervical region and the trigeminal motor nuclei. The Mass SP may be abolished in circumscribed brainstem lesions and thus may serve for localizing lower brainstem involvement.

Adult↗
PubMed1991

Pupil-sparing oculomotor nerve palsy due to midbrain infarction.

Vasculopathic oculomotor nerve palsies with pupillary sparing are thought to be due to ischemic damage to the nerve in the subarachnoid space or the cavernous sinus. We present two cases of patients with isolated pupil-sparing oculomotor nerve palsies due to midbrain infarcts. Focal ischemic midbrain lesions should be considered in cases of pupil-sparing oculomotor nerve palsies.

Adult↗
PubMed1991

Midbrain vs. pontine medial longitudinal fasciculus lesions: the utilization of masseter and blink reflexes.

Masseter (MR) and blink reflexes (BL) were investigated in 51 patients with internuclear ophthalmoplegia (INO) due to multiple sclerosis (28) and lacunar infarction (23). The MR was abnormal in 20 of 23 cases with bilateral INO and in 21 of 28 with unilateral INO. The R1 component of the BL (BL-R1) was abnormal in 7 of 23 patients with bilateral INO and 10 of 28 with unilateral INO. Combined MR and BL-R1 changes occurred in 8 of 28 cases with unilateral INO and 7 of 23 with bilateral INO. The findings provide evidence for a rostral/caudal localization of lesions within the medial longitudinal fasciculus causing INO on the basis of MR and BL-R1 abnormalities. An abnormality limited to MR suggests a midbrain location in 58.8% of patients while abnormal BL-R1 with or without an associated MR change suggests a rostral pontine location in 35.3%.

Blinking↗
PubMed1991

Spheroid-cytoplasmic complexes in a congenital myopathy.

The most striking pathological finding in the deltoid muscle biopsy specimens of 2 unrelated adult male patients consisted of large spheroid-cytoplasmic complexes of intricate structure, as previously described only under experimental conditions (Chou and Mizuno, 1986). These large cytoplasmic masses were characterized by a granular centre and a filamentous halo. Immunohistology revealed the presence of intermediate filaments of the desmin and vimentin types. Clinically, both patients showed mild and slowly progressive proximal myopathy of adult onset. In one patient, the myopathy was strongly suspected to be inherited. In concordance with previous reports on cytoplasmic and spheroid body congenital myopathies, these spheroid-cytoplasmic bodies further enlarge the spectrum of late onset congenital myopathies.

Adult↗
PubMed1990

Temperature dependence of the electrical and mechanical responses of the adductor pollicis muscle in humans.

Changes at low temperatures of the electrical and mechanical activity of the adductor pollicis muscle were studied in 10 volunteers. Decreasing temperatures resulted in increased amplitude and duration of the negative phase and peak-to-peak amplitude of the evoked muscle action potential. Distal latency, electromechanical latency, contraction time, and half-relaxation time were also increased while isometric force, contraction velocity, and relaxation velocity were decreased. The increase of contraction time is greater over the temperature range below 28 degrees C than above 29 degrees C. Skin temperature differs significantly from muscle temperature, showing about 3 degrees C lower values during cooling and up to 4 degrees C higher values during rewarming with radiant heat.

Action Potentials↗
PubMed1990

Forearm ulnar-to-median nerve anastomosis of sensory axons.

A 22-year-old man showed electrophysiological evidence of an ulnar-to-median nerve communication involving only sensory fibers. The nerve action potentials evoked by stimulation of the middle finger (ulnar side) and the ring finger (radial side) digital nerves were propagated with the median nerve at the wrist and the ulnar nerve at the elbow. He was the only subject among 30 studied with this abnormality.

Action Potentials↗
PubMed1990

Fasciculations due to verapamil in a patient with neuropathy.

A patient with pre-existing peripheral neuropathy developed generalized fasciculations under verapamil which ceased after discontinuation of the drug. It is suggested that the increase in acetylcholine (ACh) release at the neuromuscular junction by verapamil may trigger fasciculation in the state of regeneration at ACh-sensitive sites of axon terminals and immature axon sprouts.

Aged↗