Cognitive motor dissociation in patients with chronic disorders of consciousness: a literature review

Chronic disorders of consciousness include several conditions that differ significantly in both clinical and neurophysiological features. As medical technology continues to develop, the differential diagnosis of disorders of consciousness extends beyond purely clinical work. Nevertheless, all types of consciousness disorders are united by varying degrees of dissociation between wakefulness, cognitive and motor activity. The external similarity and minimal differences in clinical symptoms in unresponsive patients may hide different morphofunctional variants of this condition. In particular, use of electroencephalography and functional magnetic re- sonance imaging techniques allows us to detect covert consciousness in some clinically unresponsive patients. Based on various estimates, this phenomenon occurs in 515% of all cases. A special instance of covert consciousness is cognitive motor dissociation (CMD), defined as activation of cortical motor centers, recorded using neurophysiological techniques, in response to a corresponding instruction to perform a movement without its visible performance. Some researchers believe that detection of CMD indicates a more favourable prognosis for the subsequent restoration of consciousness, rather than its absence. The aim of this review is to examine CMD and its potential significance for outcomes in patients with chronic disorders of consciousness.

Degrees of Dissociation and Hydration Numbers of Twenty Six Strong Electrolytes in Aqueous Solutions at 25 °C

This paper brings further results on the degrees of dissociation (α) and hydration numbers (nh) of strong electrolytes in aqueous solutions at 25 °C, evaluated for the first time from osmotic coefficients (ϕ). Presented here are also the equations for the non-ideality parameters, ϕ and γ± (the mean molal ionic activity coefficient), in terms of α and nh.

Determination of limiting molar conductivities of weak organic acids in aqueous solutions

Conductance, potentiometric, and spectrophotometric measurements have been made at 25°C of aqueous solution containing sulfanilic, hippuric, mandelic, and 3,5-dinitrosalicylic acids at different concentrations. Conductance data were analyzed using the methods of Fuoss-Kraus, Kraus-Parker, and Shedlovsky for conductivity of the free ions. Using the calculated limiting conductances, activity coefficients, and degrees of dissociation, the dissociation constants of the weak acids were determined. From plots Δ vs c1/2, reliable values for Δ0 were estimated, using a computer program, and by means of an iterative method the proper value of Δ0 was determined, independently of that initially introduced. Values of pK were also obtained from potentiometric and spectrophotometric measurements. Evidence for the existence of univalent and divalent ions in aqueous solutions of 3,5-dinitrosalicylic acid was obtained spectrophotometrically, this fact justifying the poorer results provided by conductance measurements.

Degrees of dissociation and hydration numbers of six tetra alkyl ammonium halides and nineteen 2:1 strong electrolytes in aqueous solutions at 25 °C

The actual ionic concentrations and hydration numbers of some tetra alkyl ammonium halides and 2:1 strong electrolytes in aqueous solutions at 25 °C have been evaluated for the first time from the existing osmotic coefficient data.

Interpretation of properties of aqueous electrolyte solutions in terms of hydration and incomplete dissociation

The existing data on the vapour pressures, densities and e.m.f.s of concentration cells of dilute and concentrated aqueous solutions of strong electrolytes have been interpreted in terms of hydration and incomplete dissociation. Hydration numbers and degrees of dissociation have been presented for several 1 : 1 strong electrolytes at 25 °C. Thus the actual ionic concentrations of strong acids, bases and salts, hitherto inaccessible, have now been made available.