The prognostic value of somatosensory and motor evoked potentials in comatose patients.

Somatosensory and motor evoked potentials (SEP and MEP) were examined in a total of 213 patients in traumatic (n = 140) and nontraumatic (n = 73) coma. It was the aim of this study to compare the prognostic value of MEP elicited by both electrical and magnetoelectric transcranial stimulation with the use of SEP alone. According to the presence or absence of responses and the duration of central conduction time, SEP and MEP obtained during Days 1 through 3 after the onset of coma were divided into four categories and correlated with the outcome of the patients, as assessed by the Glasgow Outcome Scale. Our results clearly show that in terms of prognostic value, SEP are superior to MEP, with normal findings indicating a favorable outcome and absent responses an unfavorable outcome. On the other hand, patients with normal electromyographic responses after both electrical and magnetoelectric stimulation had favorable and unfavorable outcomes about equally. Thus, unlike SEP, normal MEP do not allow any prognostic conclusions. Only the bilateral absence of MEP in response to electrical stimulation was a definitely unfavorable prognostic sign because all of these patients died. In contrast, with magnetoelectric stimulation, neither normal nor absent responses allowed any prognostic conclusions. Therefore, the prognostic value of electrically evoked motor responses is limited, and magnetoelectric stimulation cannot be recommended in this context.     

Motor evoked responses recorded epidurally in a patient with Guillain-Barré syndrome

Summary The case of a 75-year-old man with Guillain-Barré syndrome is presented. By means of transcranial electrical stimulation and epidural recording at the spinal level L2-3, distinct potentials with a latency of 21ms were obtained when the patient was tetraplegic. At the same time electromyographic responses of the thenar and anterior tibial muscles were absent following both transcranial and peripheral nerve stimulation. The patient recovered partially within 4 weeks. It is concluded that epidurally recorded motor evoked responses allow electrophysiological assessment of the descending pathways even in severe cases of Guillain-Barré syndrome and might contribute to a more accurate prediction of outcome.     

Prognostic value of somatosensory- and motor-evoked potentials in patients with a non-traumatic coma

Summary A total of 28 patients with non-traumatic coma were studied both with somatosensory- and motor-evoked potentials. While somatosensory-evoked potentials (SEP) have proved to be useful in predicting the outcome in patients with severe brain damage, the aim of this study was to find out whether the additional evaluation of motor-evoked potentials (MEP) could contribute to a better prediction of the outcome than SEP alone. Our results clearly indicate that in terms of prognostic value, SEP are superior to MEP. Nine patients with bilaterally preserved MEP died, while all of the patients with bilaterally preserved SEP and a central conduction time 6.5 ms survived, with a Glasgow outcome score of 1 to 3. Therefore, we cannot recommend the inclusion of MEP in the prognostic evaluation of patients with non-traumatic coma.     

Multiple IgE-mediated sensitizations to enzymes after occupational exposure: evaluation by skin prick test, RAST, and immunoblot

We investigated 10 sensitized and 10 nonsensitized workers from a pharmaceutic factory who had been exposed to powdered trypsin, chymotrypsin, bromclain, papain, amylase, and lipase. Ten nonallergic subjects served as a control group. Titrated skin prick tests (SPT), RAST, and immunoblot studies were performed with all six enzymes. SPT reactivity revealed multiple sensitizations to proteolytic enzymes, i.e., papain (specifically sensitized/total number of sensitizations: 9/10), trypsin (8/10), chymotrypsin (8/10), and bromelain (7/10) and appeared to be more frequent and more pronounced than sensitizations to amylase (3/10) or lipase (3/10). The low molecular weight of proteolytic enzymes (20–30 kDa) and their biologic activity might facilitate mucosal penetration more easily and thus - compared to amylase and lipase - permit an immune response and induction of allergic hypersensitivity. Immunoblot studies demonstrated IgG-binding bands in both SPT-positive and -negative workers, indicating exposure to the enzymes, but not in 10 unexposed control subjects. IgE-binding bands of the enzymes were detected only in workers with a positive SPT reaction and/or a positive RAST result. IgG bands were more frequent and the IgG/IgE ratio was increased in workers without allergic complaints compared to symptomatic workers. This might indicate that high levels of specific IgG antibodies to enzymes arc associated with an immune response lacking allergic manifestations in spite of IgE-mediated sensitizations to the enzymes. Atopic subjects were at greater risk of developing IgE-mediated sensitization (7/10) and allergic symptoms to enzymes (5/7). However, even without risk of atopy, IgE-mediated hypersensitivity occurred in a few subjects (3/13) exposed to enzymes by inhalation for prolonged periods of time.     

Modified impulse diminishes discomfort of transcranial electrical stimulation of the motor cortex

Transcranial electrical stimulation of the motor cortex has been developed in 1980 for electrophysiological assessment of the descending pathways. However, the widespread use of this procedure is limited by its painfulness due to simultaneous excitation of the sensory receptors and muscles of the scalp, especially if higher stimulus strengths are necessary in patients with motor deficits to evoke electromyographic responses. The present invention concerns a device which allows modification of the impulse delivered by a commercially available motor stimulator. By interruption on the exponentially decreasing impulse, "cutting" it after a freely selectable time by a low resistant short circuit on the patient's side, discomfort due to excitation of the sensory receptors and muscles of the scalp can be diminished with identical electromyographic responses regarded amplitudes and latencies of the potentials, thus making electrical stimulation less painful. Considering the applied charges we found a marked reduction of charge per phase using the modified impulse as compared to the original one with the difference increasing linearily depended on the preselected voltage.     

Strukturelle Veränderungen in säuregeätztem Schmelz im konfokalen Laser-Scanning-Mikroskop

Summary The aim of the present investigation was to elucidate structural alterations in enamel subjected to acid etch technique and treatment under remineralizing conditions by means of a new microscopy technique known as confocal laser scanning microscopy (CLSM). Blocks of enamel were treated with 37% phosphoric acid and exposed for 3 weeks to an oral environment. Tomographic CLSM images were subsequently obtained and compared with controls. CLSM proved to be a reliable, highly reproducible and simple method of qualitative assessment of structural changes occurring on the surface of enamel and in areas below the surface as deep as 100 m or more. Structural alterations associated with acid application were observed to occur up to 100 m below the surface; these largely remained after exposure to an oral environment. Changes manifested as differential light reflection were detected in experimental samples in the form of a hyperreflexible zone extending as a 10 to 15 m wide band below the etched surface. This finding indicates that deposition of salivary material occurs on and below the surface of etched enamel exposed to an oral environment. Once qualitative results of CLSM are correlated with quantitative measurements, this technique may facilitate large scale remineralization studies.

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Strukturelle Veränderungen in säuregeätztem Schmelz im konfokalen Laser-Scanning-Mikroskop

Zusammenfassung Ziel der vorliegenden Studie war es, mit konfokaler Laser-Scanning-Mikroskopie (CLSM) Strukturveränderungen in säuregeätztem und unter remineralisierenden Bedingungen behandeltem Schmelz mit einer neuen mikroskopisch-tomographischen Technik sichtbar zu machen. Schmelzblöcke wurden mit 37% Phosphorsäure geätzt und drei Wochen dem Mundmilieu ausgesetzt. Danach wurden mit CLSM mikroskopische Tomogramme der Schmelzstückchen aufgenommen und mit Kontrollproben verglichen. CLSM erwies sich dabei als zuverlässige und einfache Methode, strukturelle Veränderungen in Schmelzbereichen bis etwa 100 m Tiefe reproduzierbar sichtbar zu machen. Säurebehandlung führte zu bleibenden Strukturveränderungen bis 100 m unter der Oberfläche, die auch nach Verweilen der Probekörper im Mund unter der Oberfläche beobachtet werden konnten. Veränderungen gegenüber unbehandelten Kontrollproben manifestierten sich durch unterschiedliche Lichtreflexion, speziell durch eine hyperreflexible Zone, die sich in Form eines 10 bis 15 m breiten Bandes unter der geätzten Oberfläche ausbreitete. Dieser Befund spricht dafür, daß auf und unmittelbar unterhalb der geätzten Schmelzoberfläche im Mundmilieu aus dem Speichel Ablagerungen gebildet werden. Sobald die qualitativen CLSM-Befunde mit quantitativen Ergebnissen korreliert werden, kann der Einsatz dieser Methode größere Remineralisationsstudien erheblich erleichtern.

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Herrn Prof. Dr. H. G. Sergl zum 60. Geburtstag gewidmet.

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Die Autoren danken Frau Manuela Wildt und Herrn Elmar Feuser für die labortechnische Unterstützung.