Colloidal Reactions

COLLOIDAL REACTIONS, methods for examining cerebrospinal fluid, based on its property of affecting artificial colloidal solutions and on the change in this property under the influence of various organic diseases of the central nervous system. The essence of colloidal reactions is currently unclear. Of the colloidal reactions used at present in clinical diagnosis, besides Goldsol and mastic (see Goldsol reaction, Mastic reaction), the following are most commonly used: benzoin, paraffin, collargol, and reaction with Berlin blue. Besides the listed reactions, others have been described that have less clinical significance. The reaction with benzoin resin (benzoin colloidal) was proposed (Guillain, Guy-Laroche and Lechelle; 1920), like other reactions described below, for the diagnosis of organic diseases of the central nervous system. Technique of the reaction. Solutions necessary for the reaction: 1) 10% solution of benzoin resin in absolute alcohol, 2) fresh solution of NaCl (0.01% in Aq. bisdestillata). The reaction takes place in 16 test tubes; into the 1st test tube, 0.25 cm³ of 0.01% NaCl solution is poured; into the 2nd test tube - 0.5 cm³; into the 3rd - 1.5 cm³', into the 4th and the rest - 1.0 cm³ each; then 0.75 cm³ of cerebrospinal fluid is added to the 1st test tube, 0.5 cm³ to the 2nd, 0.5 cm³ to the 3rd, mixed, and 1 cm³ from the 3rd test tube is added to the 4th; then 1 cm³ from the 4th test tube after thorough mixing is taken and added to the 5th, and so on up to the 15th. The 16th test tube is a control. After this, 1 cm³ of colloidal benzoin resin is added to each of the 16 test tubes, they are shaken and left to stand at room temperature. The result is determined after 6 or 8 hours. In the test tubes, either complete precipitation of benzoin resin with transparent liquid above the precipitate (2nd degree), or incomplete precipitation under opalescent liquid (1st degree), or absence of precipitation (zero degree) is obtained; the results are plotted on special curves. Normal fluid gives precipitation in the 6th, 7th, and 8th test tubes. Pathological changes usually occur in the first 5 test tubes, and the types of curves obtained are very similar to those in the Goldsol reaction, with the difference that in the described reaction there is no great differentiation between the curves in cerebral syphilis and paralytic ones (see curves A, B, and C). This reaction is characterized by great variability and lack of a uniform picture and constancy of curves. For the paraffin reaction of Kafka (Kafka; 1923), a colloidal suspension of white paraffin (melting point 50-52°) is used. The main solution - 0.3 paraffin + 100.0 alcohol - is heated to 50°. To prepare the colloidal suspension, equal amounts of the main solution and distilled water are taken and heated to the melting point of paraffin, after which water is quickly added to the paraffin. Procedure of the reaction: the entire reaction takes place in 10 test tubes, into which 0.5 g of 0.3% NaCl solution + 0.5 cerebrospinal fluid are poured; the dilutions are made the same as in the previous reaction. 1 cm³ of paraffin solution is added to all test tubes. Three types of changes are observed in the test tubes: 1) complete transparency or opalescence, 2) partial precipitation of paraffin and incomplete transparency of the liquid standing above the paraffin precipitate, 3) complete transparency of the upper standing liquid. The curves in this reaction are very similar to the curves in Goldsol with some small changes. This reaction has no great clinical significance. The collargol reaction was proposed by Stern and Poensgen (Stern, Poensgen; 1920); for the reaction, the following main solution of collargol is used: 1 cm³ of collargol (Argentum colloidale Heyden) in 100 cm³ Aq. destill. For the reaction, 1 cm³ of the main solution is diluted in 20 cm³ Aq. destill. Dilutions in 10 test tubes are made the same as in Goldsol (dilutions of cerebrospinal fluid from 1:7 to 1:24), and 0.5 cm³ of collargol solution is added to all test tubes. The results of the reaction in the form of cloudiness and various degrees of precipitation (5) are determined after 12-24 hours. The maximum changes in all forms of syphilis are observed between the 4th and 6th test tubes. In the case of meningitis, changes sometimes occur in the same zone as in syphilis of the central nervous system. The reaction is not specific for syphilis and is inferior to Goldsol, as it does not give differentiation between progressive paralysis and other forms of neurosyphilis. The reaction with Berlin blue was described by Behhold and Kirchberg (Behhold, Kirchberg) in 1917. The results of this reaction are less specific than in other colloidal reactions and depend on the amount of protein contained in the cerebrospinal fluid. The data obtained in progressive paralysis and acute meningitis coincide, and therefore this reaction gives nothing for the diagnosis of neurosyphilis. The technique of the reaction comes down to preparing a solution of Berlin blue: to Berlin blue in 100 cm³ of cold Aq. dest., 5 cm³ of 5% Acid, oxalic is added; before use, 1 part of the main solution is diluted in 9 parts of Aq. destill. The rest of the technique in this reaction is the same as in Goldsol. The clinical value of these colloidal reactions is not the same: the reaction with benzoin resin gives relatively more reliable results, and accordingly it is more widely used than the other listed reactions (especially in France).