Limbic encephalitis associated with systemic lupus erythematosus.

A 34-year-old woman with systemic lupus erythematosus (SLE) presented with general fatigue, seizures and memory loss. Magnetic resonance imaging of the brain showed a high signal area in the mesial temporal lobe bilaterally. Computed tomography scan of the chest and abdomen and ultrasound of pelvis detected no malignancy and tumour marker, antibodies to antineuronal antibodies (anti-Hu, anti-Ta and anti-Ma) and antibodies to voltage-gated potassium channels were all negative. The present case is limbic encephalitis (LE) associated with SLE and the pathogenesis may include autoimmunity shared. Our experience indicates that the immunologic spectrum of LE will expand to include additional immune mechanisms.

Reversible splenial lesion with restricted diffusion in a wide spectrum of diseases and conditions.

OBJECTIVE: Reversible lesion in the central area of the splenium of the corpus callosum (SCC) is a unique phenomenon occurring particularly in patients with encephalitis or encephalopathy and in patients receiving antiepileptic drugs (AED). We report MR imaging findings, clinical courses, and outcomes in eight patients with various diseases and conditions. MATERIALS AND METHODS: Eight patients with a reversible SCC lesion with transiently restricted diffusion were reviewed retrospectively. Diseases and conditions that were associated with a reversible lesion included epilepsy receiving AED (n=1), seizure from eclampsia receiving AED (n=1), mild infectious encephalitis (n=2), hypernatremia resulting in osmotic myelinolysis (n=1), and neoplasm (n=3) such as acute lymphocytic leukemia, spinal meningeal melanocytoma, and esophageal cancer. We evaluated MR imaging findings and clinical findings. RESULTS: Seven patients had isolated SCC lesions; one patient with osmotic myelinolysis showed additional parenchymal lesions. The reversible SCC lesion shape was oval (n=6) or extended (n=2). The mean apparent diffusion coefficient value of the splenial lesion was 0.40+/-0.16 x 10-3 mm2/s, ranging from 0.22 to 0.64 x 10-3 mm2/s. In a patient with osmotic myelinolysis, additional white matter lesions, shown as restricted diffusion, were revealed as not reversible on follow-up MR imaging. Neurological courses and outcomes were good in seven patients with isolated SCC lesions, but poor in one with osmotic myelinolysis. CONCLUSION: Reversible SCC lesion with restricted diffusion is apparent in a wide spectrum of diseases and conditions. Neurological courses and outcomes are good, particularly in patients with isolated SCC lesions. Knowledge of MR imaging findings and the associated spectrum of diseases and conditions might prevent unnecessary invasive examinations and treatments.

A loss of functional spinal alpha motor neurons in amyotrophic lateral sclerosis.

We obtained motor unit number estimates (MUNEs) of the hypothenar and the extensor digitorum brevis muscles in ALS patients by our new technique. One year after symptom onset, the MUNEs had decreased to +/-30% of normal. Accordingly, we suggest that 70% of functional spinal alpha motor neurons are lost in the first post-onset year in ALS.

Maximal and minimal motor nerve conduction velocities in amyotrophic lateral sclerosis.

In 15 patients with amyotrophic lateral sclerosis (ALS) and 20 age-matched control subjects, we measured the maximal and minimal motor nerve conduction velocities of the ulnar nerve as well as the action potential amplitude of the abductor digiti minimi muscle. Both maximal and minimal motor nerve conduction velocities in ALS patients were significantly lower than those in the control group. However, the difference between the maximal and minimal conduction velocities in each ALS patient was not statistically different from that in each control subject. The maximal action potential amplitude of the muscle in the ALS patients was significantly smaller than that in the control group.

Selective neurotoxicity of clioquinol on the function of the posterior column nuclei.

In the gracile nucleus of clioquinol-treated rats, the presynaptic inhibition was remarkably diminished, and the excitatory synaptic transmission was less intensely inhibited by a conditioning sural nerve volley. These changes may be the pathophysiology responsible for paresthesia and/or dysesthesia in patients with subacute optico-myelo-neuropathy (SMON).

Maximal and minimal motor nerve conduction velocities determined by a collision method: correlation with axonal conduction velocity of type-identified motor units.

Maximal and minimal motor nerve conduction velocities of the medial gastrocnemius (MG) muscle nerve were measured by a new collision method in 20 rats of 8-9 weeks of age; the rate of tension increase produced by the muscle was also recorded. Single motor unit analysis in the other 20 rats obtained axonal conduction velocity and contractile properties of type-identified MG motor units. Comparison of the data from these experiments revealed that the maximal and minimal motor nerve conduction velocities obtained by this collision method were most likely to be the axonal conduction velocity of fast-twitch and slow-twitch motor units, respectively. Therefore, these motor nerve conduction velocities in man may also be used as functional parameters of human fast-twitch and slow-twitch motor units, respectively.

Blood brain barrier destruction in hyperglycemic chorea in a patient with poorly controlled diabetes.

A case of hemichorea in a patient with poorly controlled diabetes is reported. T1-weighted magnetic resonance imaging (MRI) showed an unusual homogeneous high-intensity area in the corpus striatum. Of interest in the case was the fact that the globus pallidus, which was enhanced with gadolinium at the onset of hemichorea, showed homogeneous high-intensity on a subsequent T1-weighted image. This indicated that blood brain barrier destruction preceded the signal intensity change in the basal ganglia. As far as the authors could determine, this is the first reported case showing such enhancement during the course of diabetic hemichorea.

The pattern of antiganglioside antibody reactivities producing myelinated nerve conduction block in vitro.

We studied the pattern of human antiganglioside antibody reactivities causing an acute conduction block in rat myelinated nerve fibers, using an in vitro preparation of the sciatic-tibial nerve. With the aid of complements, IgM antibodies reacting with the terminal disaccharide of galactose (beta1-3)N-acetylgalactosamine produced the block. These findings may help us to understand the mechanism in which the conduction block occurs in neuropathies associated with antiganglioside antibodies.

[A motor unit number estimate (MUNE)--a quantitative and pathophysiologic parameter for amyotrophic lateral sclerosis (ALS)].

We performed rate studies to develop a new method to obtain a MUNE reflecting the number of spinal alpha-motor neurons (MN). In the physiological part, six unitary muscle action potential (uMAPs) of the medial gastrocnemius muscle (MG) were averaged to obtain the mean uMAP, and a MUNE was calculated by dividing the area of its compound muscle action potential (CMAP) by the area of the mean uMAP. In the anatomical part, cholera toxin was injected into the MG muscle, and we counted the number of MG MNs identified by immunohistochemical staining of the toxin in their somata. We found that a MUNE of the MG muscle was consistent with the number of MG MNs. In the clinical application, we obtained MUNEs in 10 patients with ALS and 20 control subjects. In each patient we recorded 10 uMAPs and CMAP at each of the hypothenar and extensor digitorum brevis muscles using fine needle electrodes placed in these nerves. MUNEs for these muscles were calculated in the same way as described above. In the ALS patient group at one year post-onset of symptoms, the MUNEs for these two muscles were decreased to about 30% of the norm. We concluded that progression of ALS could be quantified by MUNEs.

[Disorders of the nervous system associated with the acquired immunodeficiency syndrome (AIDS)-clinical approach].

The acquired immunodeficiency syndrome (AIDS) is caused by human immunodeficiency virus (HIV) and characterized by disorders of the nervous system in addition to opportunistic infection and cancer. Centers for Disease Control (CDC) recommend the classification system consisting of four major groups. Group I is patients with acute HIV infection, and Group II is asymptomatic carriers. Group III is those with persistent generalized lymphadenopathy (PGL). Group IV includes five subgroups: IVA with constitutional disease, IVB with neurologic disease, IVC with secondary infectious diseases, IVD with secondary cancers and IVE with other conditions. The nervous system disorders are classified into two types: one is produced by HIV itself and not directly related to immunodeficiency, and the other caused by opportunistic infectious agents and cancers. The former is further divided into two kinds: atypical aseptic meningitis and acute inflammatory demyelinating polyneuropathy (AIDP) occur mainly in Group I and II, whereas HIV encephalopathy, distal symmetric polyneuropathy (DSPN) and vacuolar myelopathy in Group III and IV. Group I or II patients have no apparent medical problems. Therefore, when neurologists see patients with risk factors for HIV infection presenting with atypical meningitis or AIDP, it is of utmost importance to have a high index of suspicion and to look for evidence of HIV infection.

[Analysis of dysarthria in amyotrophic lateral sclerosis--MRI of the tongue and formant analysis of vowels].

To evaluate dysarthria in patients with ALS, we used MRI (gradient rephasing echo method) and compared it with the computed acoustic analysis. Five ALS male patients of progressive bulbar palsy type and five normal male were asked to phonate the five Japanese vowels, /a/./i/./u/./e/./o/. MRI of the sagittal tongue and vocal tract was obtained by the gradient rephasing echo method (0.2 Tesla, TR:30 ms, TE:10 ms, FA 25 degrees C, Hitachi). We could clearly visualize the change of tongue shape and the narrow site of the vocal tract for each vowel phonation. In normal subjects, the tongue shape and the narrow site of the vocal tract were distinguishable between each vowel, but unclear in ALS. Acoustic analysis showed that the first formant frequency of /i/./u/ in ALS was higher than normal and the second formant frequency of /i/./e/ in ALS was significantly lower than normal. The discrepancy from the normal first, second and third formant frequency for each vowel of ALS was most seen in /i/./e/. It was speculated that /i/ and /e/ were the most disturbed vowels in ALS. The first and second formant frequency of vowel depends on the tongue shape and the width of the oral cavity. Therefore the results of the acoustic analysis in ALS indicated poor movement of tongue in /i/./u/./e/ and were compatible with the findings of the sagittal tongue MRI. The sagittal view of the tongue in the gradient rephasing echo MRI and the acoustic analysis are useful in evaluation dysarthria in ALS.

[A case of distal myopathy with rimmed vacuole formation, progresses into proximal-dominant muscle involvement].

A case of 55-year-old male with distal myopathy with rimmed vacuole formation is reported. He first noticed dragging of his legs at the age of forty-three. Two years later, he was evaluated to have muscle wasting and weakness in lower legs. In another ten years, he became unable to stand or walk unaided. On physical examination, proximal limb muscles were more severely affected than distal limb muscles. Notably, muscle strength of the quadriceps femoris muscles were weak (MRC Scale 3/5), compared to hamstrings, tibialis anterior muscle and gastrocnemius muscle (4/5). Serum creatine kinase, electromyography, nerve conduction velocities were all compatible with this diagnosis. A computed tomography of the musculoskeletal system was consistent with physical findings. Muscle biopsy revealed many fibers with typical rimmed vacuoles (approximately 6% of fibers). Additionally, small amount of ragged-red fibers (0.5%) was noted. Histochemical reaction showed a focal deficiency of cytochrome c oxidase. This case suggests that during the longstanding course of the illness, proximal limb muscles may be more severely affected, and quadriceps femoris muscle may be predominantly involved.

[Immunologic diagnosis of central nervous system viral infection].

Immunologic diagnosis of central nervous system viral infection requires paired sera, obtained at the onset of symptoms and in the convalescent period. Titers of antibodies against a particular virus in these samples should be obtained under the same conditions. As a screening test, the complement fixation or hemagglutination method is used. On the other hand, the neutralization, the enzyme-linked immunosorbent assay (ELISA) or the Western blot method is used as a confirmatory test. An antibody capture ELISA is especially effective for detecting viral antibody in the cerebrospinal fluid. Although a four-fold or greater increase in a viral antibody titer is serologically considered indicative of active viral infection, it may be clinically irrelevant. Accordingly, clinical correlation should always be sought when interpreting the results of the viral titer assay.

Firing of spinal motoneurones due to electrical interaction in the rat: an in vitro study.

The excitatory interaction between spinal motoneurones was investigated by means of electromyogram (EMG) recordings from hindlimb muscles as well as intracellular ones from their innervating motoneurones in the isolated preparation of immature rats. Stimulation of the muscle nerve to biceps femoris or medial gastrocnemius or of the L5 ventral root evoked early and late EMG responses in the muscle of the preparations with the dorsal roots cut. The early response was produced directly by volleys in the motor nerve. The late response was of spinal origin, since it disappeared after the severance of the ventral root. The thresholds and the conduction velocities of nerve fibres, which conducted the centripetal impulse causing the late response, were compatible with those of motor nerve fibres. The amplitude of the late response was 5-10% of that of the maximum early EMG response. Intracellular recordings from spinal motoneurones revealed that stimulation of the ventral root elicited the double discharge composed of antidromic and delayed spike potentials. The delayed spike was never evoked after the spike potential elicited directly by a short depolarizing pulse. The double discharge was observed in about 6% of the motoneurones examined. The threshold of the stimulus intensity evoking the double discharge was in the range of those of motor nerve fibres. The latencies of the delayed excitation were 7.0-9.0 ms, comparable to the intraspinal delays of the late EMG response. Stimulation of the ventral root at intensities subthreshold for antidromic activation was found to produce a small depolarizing potential in about 60% of the motoneurones examined. The amplitudes were 0.5-5.0 mV, and the onset and the peak latencies 2.0-7.0 ms and 5.0-8.0 ms, respectively. The potential was unaffected by the deficiency of calcium ions in the perfusing medium and persisted after the degeneration of the afferent fibres in the ventral root.(ABSTRACT TRUNCATED AT 250 WORDS)

Normal maximal and minimal motor nerve conduction velocities in adults determined by a collision method.

Using a new collision method, we measured motor nerve conduction velocities of the ulnar nerve in the forearm and the action potential amplitude of the abductor digiti minimi muscle on 60 adults, ages 20 to 82 years and apparently free from diseases of the peripheral nervous system. Both maximal and minimal motor nerve conduction velocities were linear functions of age; 64.42-0.05 age and 60.45-0.12 age, respectively. The percentage of the minimal to the maximal motor nerve conduction velocities was expressed as 94.45-0.13 age. The maximum amplitude of evoked muscle action potentials was also correlated with age. This novel method may be useful in detecting pathology of motor nerve fibers which results in a decrease in submaximal conduction velocities.

Origins of the scalp-recorded somatosensory far field potentials in man and cat.

Short latency somatosensory evoked potentials preceding the primary cortical potential were recorded from the scalp in man and cats. Four positive potentials (P1, P2, P3 and P4 in man, and CI, CII, CIII and CIV in cats) were observed with non-cephalic reference recording and 3 or 2 positive components (P1a, P2a and P3a in man, and CIa and CIIa in cats) were recorded with earlobe reference. (1) The latencies of these potentials and the effects of lesions on them in man and (2) the effects of (i) supracollicular and medullo-cervical transections and (ii) intrathecal anaesthesia of the cervical cord on these components in cats suggest that: (1) P1 and CI originate in the brachial plexus beneath the clavicle; (2) P2, P3 and CII, CIII are generated in the cervical cord; (3) P4 and CIV reflect activity mainly in the brain stem or the cerebellum or both; (4) P1a and CIa arise in the cervical cord; (5) P3a and CIIa reflect activity mainly in the brain stem or the cerebellum or both. As the impulse initiated in the median nerve travels through various regions where the resistance might change suddenly, these far field potentials might be recorded as if generated at fixed sites such as just beneath the clavicle and foramen magnum.