Observation of charge-density-wave excitations in manganites.

In the optical conductivity of four different manganites with commensurate charge order (CO), strong peaks appear in the meV range below the ordering temperature T_{CO}. They are similar to those reported for one-dimensional charge density waves (CDW) and are assigned to pinned phasons. The peaks and their overtones allow one to obtain, for La_{1-n/8}Ca_{n/8}MnO_{3} with n=5, 6, the electron-phonon coupling, the effective mass of the CO system, and its contribution to the dielectric constant. These results support a description of the CO in La-Ca manganites in terms of moderately weak coupling and of the CDW theory.

MR of leptomeningeal spinal and posterior fossa amyloid.

We report an unusual cause of leptomeningeal MR enhancement, amyloid, along the surfaces of the spinal cord and brain stem and in the spinal subarachnoid space, with sacral intradural and epidural deposition. Type I familial amyloid polyneuropathy may cause amyloid deposition along the leptomeninges of the spinal cord and brain in addition to the visceral organs and the peripheral somatic and autonomic nerves.

Segmental zoster paresis of limbs.

Segmental zoster paresis (SZP) is the focal, asymmetrical neurogenic weakness which may occur in a limb affected by cutaneous zoster. We have summarized the features of this syndrome, based on a retrospective review of 8 personal and 96 published cases. Limb SZP becomes apparent in at least 3-5% of patients with cutaneous zoster, who are usually over the age of sixty and weak proximally (C5,6,7 or L2,3,4 innervated muscles). Functional motor recovery occurs in about 75% of cases, generally by 1-2 years. Limb weakness is probably due to a lesion of the ventral nerve root, in close proximity to the initiating dorsal ganglionitis. The electrodiagnostic findings, scarce in the literature, typically consist of absent compound sensory nerve action potentials in the involved limb, with less frequent reduction or loss of compound muscle action potentials. Fibrillations and positive sharp waves become detectable within 1-4 months in limb and related paraspinal muscles, decreasing or disappearing later. In addition to this radiculopathy, peripheral nerves may also occasionally become involved, manifest as mononeuropathies of the median, ulnar, long thoracic, recurrent laryngeal, and phrenic nerves. The zoster infection or consequent inflammatory response appears able to affect motor axons distally as well as proximally.

A standard test of heat-pain responses using CASE IV.

Heat-pain threshold and stimulus response characteristics can be evaluated with graduated heating pulses from a radiant heat source or a contact thermode. Results may be used to: (1) evaluate differences in sensation among anatomical sites, sides of the body, and with development and aging; and (2) provide an end-point for the study of the efficacy of drugs; or to follow the course of sensory alteration in disease (medical practice, epidemiologic studies, and controlled clinical trials). Because there is great variability in how tests of this kind are performed and scored, comparisons of results among medical centers are difficult. To meet this need, we have developed, and here describe, a standardized and validated test of heat-pain. We use both pyramidal and trapezoid-shaped stimuli. The range of stimulus magnitudes we recommend is sufficient to test heat-pain at a sensitive region (the face) of young people and an insensitive region (the foot) of healthy old people. From tests on healthy subjects and patients, we find that neither our previously published forced-choice or 4, 2, and 1 stepping algorithms are suitable for testing heat-pain sensation. We, therefore, introduce the Non-Repeating Ascending with Null Stimuli (NRA-NS) algorithm which performs satisfactorily. The graphed data points of responses to increasingly stronger heat pulses were made up of two components-the no pain (0) response line and the heat-pain response line (> or = 1 numerical scaling of the pain responses graded from 1 [least] to 10 [greatest]). For the pain responses, we found that usually a curve could be fit using a quadratic equation. Using this equation, or interpolation where necessary, it is possible to compute the heat-pain detection threshold (HPDT or HP:0.5), an intermediate heat-pain response (HP:5.0), and the difference between the two (HP:5.0-0.5). Our studies show that a certain time is needed between successive stimuli and tests to minimize changing basal skin temperature or threshold. We also demonstrated that low or high baseline skin temperatures can affect heat-pain responses, therefore, we advocate specific testing conditions. Based on a study of 25 healthy subjects, the reproducibility of the test falls within +/-1 stimulus steps 88% of the time for HP:5.0 and 76% of the time for HP:0.5. The precise approaches employed to make the test standard and reproducible are described. We illustrate that the algorithm and testing system is able to document altered pain threshold with skin abrasion, with intradermal injection of nerve growth factor, and with diabetic polyneuropathy.

Quantitative sensory testing: methodology, applications, and future directions.

Quantitative sensory testing (QST) is based on well-developed psychophysical methods that define not only the stimulus (type, characteristics, quantity, presentation, testing format, and environment) but also the response (form and analysis). With the availability of personal computers, transducers, electronic circuitry, and specially written software, it became possible to develop systems that delivered physical stimuli with waveforms that were precisely defined, quantitated, and graded over a broad range of magnitudes, and capable of eliciting unitary sensations. Specific algorithms of testing and finding threshold could now be programmed for exact and sequential error-free testing. Results could also be efficiently and accurately printed out and compared with normal values with consideration of modality, site, gender, height, and weight. QST's main application is in quantifying modality-specific detection thresholds (and some suprathresholds also) in health (by site, side, development, aging, and other) and in disease (involving sensory receptors, nerve fibers, central nervous system tracts, or cerebral association areas), allowing it to play the unique role of standardizing the clinical examination. Used to identify modality-specific sensory loss it can, for example, be correlated with the compound action potential of sural nerve in vitro and with the number and sizes of fibers. In detecting patterns of sensory abnormality, it can also suggest the presence of specific diseases and be used to follow the course of sensory loss. Finally, because it is the best approach to detect, characterize, and quantitate sensory abnormality, it is useful both in epidemiologic and controlled clinical trials. Although our review focuses especially on the approaches and system we have developed, other systems using standardized approaches are available allowing the evaluation of vibratory (VDT), cooling (CDT), and warming (WDT) detection thresholds and visual analog scaling of heat pain (HP VAS).

Venous infarction following translabyrinthine access to the cerebellopontine angle.

Between July 1988 and August 1992, 141 tumors of the cerebellopontine angle were surgically removed through a variety of transtemporal approaches. Superior petrosal sinus resection was performed in 44 of these patients with either large tumors in the vertical dimension or contracted mastoid anatomy, in an effort to enhance intradural tumor exposure and facial nerve identification. Three patients who underwent superior petrosal sinus resection developed early postoperative temporoparietal venous infarction with transient expressive aphasia. The ipsilateral cavernous sinus was entered and packed during tumor dissection in all three cases, and one patient also had sacrifice of the petrosal vein. This report reviews intradural cortical venous anatomy as it relates to transtemporal access to the cerebellopontine angle. Three cases of postoperative venous infarction are presented to emphasize the importance of the venous collateral circulation to the cavernous sinus in patients having undergone superior petrosal sinus resection.

Effects of ORG 2766, a neurotrophic ACTH4-9 analogue, in neuroblastoma cells.

Treatment of Neuro2a cells with drugs known to affect the integrity of microfilaments and microtubules, as well as with a calcium ionophore produced damage to the cellular membrane that was quantifiable by measuring the release of LDH into the culture medium. Concurrent exposure of the cells to ORG 2766 was found to modulate the release of LDH in a dose- and time-dependent fashion. ORG 2766 treatment was also able to reduce the basal release of LDH into the culture medium. [table: see text] The ORG 2766-induced reduction in LDH release was not due to down-regulation of protein synthesis. The peptide produced significant increases in protein synthesis relative to control conditions at concentrations of 10(-11) to 10(-6) M with 10(-8) M being an optimal dose. SDS-PAGE and 2-D PAGE analysis showed that de novo synthesis of most polypeptides was increased by about 40%. Additionally, a family of polypeptides tentatively identified as actins appear to undergo ORG 2766-dependent post translational charge modifications. These data are consistent with the hypothesis that regulation of transcription and/or translation are mechanisms important to the neurotrophic actions of ORG 2766.

Quantitative sensory threshold testing in patients with multiple sclerosis.

Cutaneous thresholds for vibratory and thermal stimuli were quantitated at the index finger and great toe of twelve patients with definite multiple sclerosis. Nine of 12 (75%) patients had abnormalities to either modality, especially at the great toe, where 48% of vibratory and 17% of thermal thresholds were abnormal. Of ten patients undergoing somatosensory evoked potential (SSEP) testing, 8 (80%) had abnormal median and 9 (90%) had abnormal tibial studies. While more experience is needed to determine the sensitivity of quantitative sensory threshold testing in this application, this simple, noninvasive technique appears to correlate both with clinical and SSEP findings.

Renal causes of elevated sedimentation rate in suspected temporal arteritis.

The erythrocyte sedimentation rate (ESR) is a frequently used but nonspecific indicator of inflammation or infection. Clinicians often check an ESR in patients with symptoms of headache, facial or jaw pain, and visual loss, as an aid in the diagnosis of temporal arteritis. We present two patients with these complaints, who did not have temporal arteritis, nor any other inflammatory condition or infection, but had ESRs near or above 100 mm/h, leading to diagnostic confusion. An occult nephrotic syndrome, with or without renal insufficiency, can cause such a highly elevated ESR, and was discovered in these patients.

Prediction of early beneficial response to plasma exchange in Guillain-Barré syndrome.

We attempted to identify predictive factors of early beneficial response to plasmapheresis in Guillain-Barré syndrome (GBS). We reviewed 24 patients with typical severe GBS who underwent plasmapheresis and analyzed their outcome at one month. One group of 14 patients, designated as responders, improved dramatically, while ten patients showed little response. Age was the only important clinical predictor, with responders being younger. No other clinical variable (sex, preceding illness, severity, timing of plasmapheresis, cranial nerve involvement, or cerebrospinal fluid findings) reached significance. Among electrophysiologic parameters obtained before plasmapheresis, the amplitudes of compound muscle action potentials with distal stimulation of median and peroneal nerves were significantly reduced in non-responders. Plasmapheresis may improve only a subgroup of patients with GBS. Among patient characteristics, age and amplitudes of compound muscle action potentials are important predictors of early responsiveness.

Excellent results with clorazepate in recalcitrant childhood epilepsies.

Eleven children with severe incapacitating generalized seizures were treated with sodium valproate and clorazepate and responded with a marked decrease in seizure frequency. Three children received clorazepate alone, either because of valproate toxicity or because of parental concern over side effects. These children, 5 males and 6 females, ranged in age from 3 to 17 years. They manifested normal to severely retarded intelligence. Although valproate levels were in the therapeutic range, seizure control was inadequate. When clorazepate was added to valproate therapy a marked reduction in seizure frequency occurred within 24 hours and became optimal within 48 to 72 hours. Side effects were minimal with the exception of a nocturnal generalized tonic-clonic seizure in a single patient. Three children were withdrawn from therapy after a year because of recurrent seizures. One patient was restarted on therapy after 6 months and seizure control improved. Clorazepate may be a useful adjunct in the treatment of primary generalized seizures in children.

The success of EEG in confirming epilepsy--revisited.

This study was designed to re-examine the question of how sensitive the first EEG is in confirming a definite seizure disorder. Patients (358) with a diagnosis of "epilepsy" were randomly selected and their EEGs reviewed. An abnormal EEG was found in 84% (epileptiform paroxysms in 77-82%), while 16% had a normal tracing. However, after careful review with up to 7 years of follow-up, slightly more than 1/2 of those with a normal EEG did not actually have epilepsy, 1/4 did and in the remaining 1/4 insufficient information was available for a definite diagnosis. The incidence of normal records among patients with definite epilepsy then fell to 4.7%. With the evaluation of additional patients with "epilepsy" and a normal EEG (200), a similar distribution was found. The final diagnosis for the group without seizures was a behavioral-psychiatric condition in 1/4, syncope in 1/5 and pseudoseizure in 1/6.

Small sharp spikes revisited: further data on this controversial pattern.

This study investigated the question of whether small sharp spikes (SSS) are associated with seizures (sz) or represent a completely normal finding. From an EEG laboratory with many referrals with epilepsy, a 48% incidence of clinical sz in pts with SSS was significantly higher than the 15% in pts with normal EEGs, but lower than the 78% in pts with SSS and other paroxysms; the type of sz in the SSS pts was more often partial than the sz associated with normal EEGs. When abnormal records with other non-controversial paroxysms were followed for up to 32 yrs and changed to normal tracings, a decrease in sz was found significantly more often than when the paroxysms were replaced by SSS. In addition, if pts with only SSS lost this pattern in time, sz also tended to resolve, as opposed to sz remaining in the majority who continued to show the SSS pattern. A clear inverse relationship was found between the incidence of sz and age in pts with this waveform. Our evidence argues against the SSS as a completely normal finding, but instead suggests that it is a pattern with a moderate degree of epileptogenicity that is clearly age-dependent.