EVALUATION OF THE AUTONOMIC NERVOUS SYSTEM RESPONSE BY PUPILLOGRAPHICAL STUDY IN THE CHEMICALLY SENSITIVE PATIENT

 

Shinji Shirakawa, M.D., Fellow, Environmental Health Center Ė Dallas Dept. of Ophthalmology, School of Medicine, Kitasato University, Kanagawa, Japan.

William J. Rea, M.D., F.A.C.S., Director of the Environmental Health Center - Dallas, First World Chair in Environmental Medicine, Robens Institute. The University of Surrey, Guildford, England.

Satoshi Ishikawa, M.D., President of Neuro-Ophthalmological Society, Japan, Professor and Chairman of Ophthalmology, School of Medicine, Kitasato University, Kanagawa, Japan.

Alfred R. Johnson, D.O., Staff Environmental Health Center-Dallas.

This research is supported partially by grants from Hamamatsu Photonics and American Environmental Health Foundation.

_____________________________________

ABSTRACT

We evaluated the status of the autonomic nervous system (ANS) using open loop pupillography in forty-three chemically sensitive patients, proven either by intradermal or inhaled challenge under environmentally controlled conditions, and eighteen well volunteers. Twenty out of forty-three patients had organochlorine pesticides in their blood and twenty-three patients had chemical solvents (aliphatic and aromatic) in their blood. The significant differences of autonomic nervous system function were seen in the velocity of constriction of the pupil (P <0.3) and dilatation time of the pupil (P<.03) in the chemical solvents patientís group, compared to the well volunteer group. In the pesticide patientís group, the significant differences were seen, not only in the velocity of constriction (P<.001) and dilatation time (P<.02), but also in pupil area (P<.006), and velocity of dilatation (P<.001) showing dysregulation of their autonomic nervous system. The pupillary abnormalities, which were the result of disturbances in the autonomic nervous system, were seen in thirty-three out of forty-three chemically sensitive patients (77%) by pupillographical examination, as compared to a healthy volunteer group. The inhibitory (sympatholytic) type of autonomic nervous system function was seen in twenty-one of thirty-three patients (63.6%), while cholinergic changes were seen in nine patients (27.3%).

INTRODUCTION

Recently, the effect of various environmental toxins, such as aliphatic and aromatic solvents and pesticides, have become a serious problem for man., These environmental toxins may trigger various diseases for a person who has an overload of solvents and pesticides, depending on the individualís susceptibility, the total body load, and the state of his nutrition. It has been observed by many clinicians that recurrent exposure to the environmental pollutants may cause many early symptoms and signs of autonomic nervous system dysfunction. Many patients who are exposed to chemical solvents and pesticides have similar symptoms and signs, such as headache, dizziness, constipation, and diarrhea, which may be caused by disturbances of the ANS. It is well known that the initial effect of organophosphate pesticides on the ANS is fundamentally a cholinergic reaction, but those of organochlorines are not as clearly defined. The chemically sensitive often present with symptoms which might be ascribed to disturbances of the ANS. We hypothesized that these reactions might be due to the ANS being damaged by chemicals to which the patient was sensitive. To test this hypothesis we decided to study pupillary responses in a group of patients who were chemically sensitive and in a group of healthy volunteers, to see if there was any evidence that the hypersensitive group had disturbances.

We evaluated the autonomic nervous function using open-loop pupillography in forty-three chemically sensitive patients.

METHOD AND MATERIALS

Patients

Forty-three chemically sensitive patients (eighteen males and twenty-five females), who had symptoms of autonomic nerve disturbance proven by intradermal and/or inhaled challenge, were examined. All had known exposures to pesticides or chemical solvents - either by acute repeated exposure or chronic long-term "low-level" exposures. Of these, twenty (age 23-68) had organochlorine pesticides and twenty-three (age 9-63) had chemical solvents (aliphatic and aromatic) in their blood. All had developed chemical sensitivities after exposure to these substances; their chemical sensitivities were confirmed by intradermal and/or inhaled challenges. Blood pesticide or chemical solvent levels were measured by Laseterís high resolution glass-capillary gas chromatographic methods before this examination. The organochlorine pesticides were one or more of the following: DDT, DDE, beta-BHC, heptachlor epoxied, hexachlorobenzene, chlordane and dieldrin, toluene, xylene, chloroform, dichloromethane, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene, and dichlorobenzene. We also examined eighteen healthy nonsmoking volunteers, (11 females and 7 males) aged 25-45 years, who were free of both ocular disease and disorders known to affect the function of the ANS.

Pupillography

Pupillary light reflex was measured by open-loop pupillography (Binocular Iriscorder C2515 Hamamatsu Photonics) in forty-three chemically sensitive patients and eighteen healthy controls under environmentally controlled conditions. Pupillary light reflex is measured after dark deadaption for 15 minutes followed by a challenge flash of 200 IU of light. The parameters measured are seen in Figure 1. Pupillary light reflexes are mediated by the ANS as well as by the optic nerve. This is especially true for the pupil area (A1), time of constriction (T2) and dilatation (T5), velocity of constriction (VC), and dilatation (VD). These actions are dependent on the ANS; T2, VC, T5 and VD are related to parasympathetic function, and T5 and VD which are related to the parasympathetic nerve function. T5 and VD are related to sympathetic function. This function can be qualified, giving the test a high degree of objectivity and accuracy.

Disturbances of the ANS are divided into four types, i.e. sympathomimetic, sympatholytic, cholinergic, and cholinolytic which are due to stimulation and inhibition of both sympathetic and parasympathetic nerves.

Sympathomimetic responses are those consisting of big pupil size (A1), increased time of constriction (T2) decreased maximum acceleration of constriction (AC), decrease in time to recover to 63% of pupil area change after light constriction (T5), and increase in maximum velocity of dilation (VD). Sympatholytic responses include decreases in pupil area (A1), in constriction rate (CR), in T2, in VD, and increases in T5. Cholinegeric responses are indicated by decreases in A1, CR, T2, VC, AC, and VD: no changes in T5. Cholinergic responses differ from sympatholytic responses in that T5 is prolonged in sympatholytic responses and normal in cholinergic, while decreases occur in VC and AC in cholinergic but not in sympatholytic responses.

Figure 1 Not shown

Cholinolytic responses are increased in A1 and VD with decreases in CR, T2, VC, AC, and T5. They differ from sympathomimetic responses in that cholinolytic responses have decreases in CR and VC, while sympathomimetic responses have no change in these parameters.

The method of division for the four types of ANS disturbances followed Utsumiís guidelines developed from results of pupillography studies performed under experimental disturbances of the autonomic nerve using eye drops with adrenergic and cholinergic medications.

All measurements were performed in subjects who had been dark adapted for at least fifteen minutes. Studies were done at a constant time span during the day from 9am to 4pm in order to minimize the influence of the diurnal autonomic nerve variation. These examinations were done in a less-chemically and particulate contaminated environmentally controlled room designed by the method of Rea.1,2

RESULTS

The chemically sensitive patients fell into two groups, those with organochlorine pesticides and those with solvents in their blood.

Comparison of the patient groups and the volunteer group in pupillography

Studentís t-test was used in the comparison of the patient groups and the control group. The significant differences were seen in velocity of constriction (VC) and dilatation time (T5) with patients who had aliphatic and aromatic chemical solvents in their blood. The VC was slow (P<.03) and T5 was prolonged (P<.03) (Table 1) compared with the control group. The significant differences in the pupil area (A1), velocity of both constriction (VC) and dilatation (VD), and dilatational time (TA5) were also seen in patients whose blood contained chlorinated pesticides. The A1 was small at P<.006 (Table 1). Both VC and VD were slow (P<.001) and T5 was prolonged (P<.02) compared with the volunteer group (Table 1).

 

 

 

Evaluation of autonomic nerve function in patients.

Autonomic nerve disturbances were revealed in thirty-three out of forty-three patients (76.7%) by pupillographical examination. It was seen in eighteen of twenty patients (90%) with chlorinated pesticides, and in fifteen of twenty-three patients (65%) with chemical solvents in their blood (Table 2). No ANS disturbances were seen in ten patients, when performing pupillographical examination, even though they had the same symptoms related to the ANS as the other patients.

When analyzing the types of ANS disturbance on pupillographical examination in the thirty-three patients (Table 3), the sympatholytic type was seen in twenty-one of thirty-three patients (63.6%), and the cholinergic type was seen in nine of thirty-three patients (27.3%). Both the cholinolytic (6.1%) and sympathomimetic type (3.0%) were seen with a small degree; the sympathomimetic type was not found in the pesticide patientís group.

In the distribution of the ANS disturbances in each group, the sympatholytic type was seen in a high degree with both groups (73.3% of chemical solvents patients; 55.5% of pesticides patients). However, the degree of both cholinolytic and sympathomimetic types were very small in each group. The sympatholytic type was seen in a high degree with chemical solvents patients (73.3%) compared with the cholinergic type (13.3%). However, in the pesticide patients, there was not much difference between the sympatholytic (55.5%) and the cholinergic type (38.9%). They were clinically indistinguishable.

 

 

 

 

 

 

Table 1

Comparison of the patient groups and volunteer group in pupillography

 

 

 

A1

 

CR

 

T2

 

VC

 

T5

 

VD

 

Number

Mean

Age

Chemical

Solvents

34.2

0.47

211.6

43.41

2438.71

10.6

23

41.5

+7.6

+0.07

+30.1

+8.6

891.7

+2.9

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Chlorinated

Pesticides

228.62

0.45

215.7

37.83

2667.64

8.4

20

45.4

+9.9

+0.11

+53.3

+10.1

+1239.2

2.3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Control

36.9

0.48

205.4

49.6

1881.8

12.2

18

29.7

 

 

+6.0

+0.07

+20.6

+8.5

+555.5

+3.2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Significance

Difference:

 

1:p<.03

 

2:p<.A006

 

3:p<.001

 

4:p<.02

 

 

 

 

 

 

 

 

measured in the controlled environment (Mean Ī S.D.)

 

 

Table 2

Frequency of Autonomic Nerve Disturbance

by Pupillographical Result in Each Group

 

 

 

Number

of Pts

No. of Pts.

with A.N.D.

Chemical

Solvents

23

15 (65%)

 

 

 

 

Chlorinated

Pesticides

20

18 (90%)

 

 

 

 

Total

43

33 (77%)

Table 3

Distribution of Autonomic Nerve Disturbance in Each Group

 

 

Chemical

Solvents

Chlorinated

Pesticides

 

Total

 

 

 

 

 

 

 

 

Cholinergic

2 (13.3%)

7 (38.9%)

9 (27.3%)

Cholinolytic

1 (6.7%)

1 (5.6%)

2 (6.1%)

Sympathiomimetic

1 (6.7%)

0 (0%)

1 (3.0%)

Sympatholytic

11 (73.3%)

10 (55.5%)

21 (63.6%)

Total

15

18

33

 

DISCUSSION

The number and variety of environmental toxins in air, food, and water has increased in the last several years following industrial development. These environmental toxins invade the body subtly and influence the homoeostatic mechanisms.1,2 These chemical solvents and pesticides may gradually build up to increase the total body load. As the result of this increased load, sensitivity may develop to environmental toxins such as chemical solvents and pesticides as well as other substances. By 1980, of the 70,000 manufactured types, over 400 synthetic chemicals had been identified in human tissue, particularly in tissues containing fat molecules. It has been long suspected that chemical toxins damage the ANS. Clearly, occasional ANS responses may be mediated through IgE mechanisms, but a more likely mechanism is the release of mediators or by the actual direct stimulation by the incitant. Substitution of toxic substances for nerve mediation, or a direct damage to the autonomic nerves, or synapse mediators may also be involved. However, until lately no devices were available to measure the response of the ANS to pollutant exposure.

The purpose of this present study was to see if objective measurements of the ANS dysfunction could be recorded using open-loop pupillography under environmentally controlled conditions in chemically sensitive patients who had solvents and pesticides in their blood. Indeed, in the patients with aliphatic and aromatic solvents in their blood, the VC was significantly slow, and the T5 was significantly prolonged compared to the control group. From these results, it is suggested that the autonomic nerve function in the patients with chemical solvents in their blood is a change in both sympathetic and parasympathetic nerves. This would suggest a depressive effect on the whole system. In the case of patients with pesticides in their blood, the significant differences were seen, not only in VC and T5, but also pupil area A1 and velocity of dilatation (VD) compared to the control group. This result also suggests that the pesticide patients have severe dysfunction of both sympathetic and parasympathetic nerves. One might expect these results since many pesticides and solvents are known to suppress the central nervous system. They appear to have a generalized adverse effect, not only on immune function, but also on neuro vascular function. These data suggest that the chemical solvents and the chlorinated pesticides cause the dysfunction of the autonomic nervous system, as compared to the organophosphate pesticides which initially cause the hyperfunction of the autonomic nervous system.3 Since it is impossible to totally evaluate total load, it is not certain that all the effect on the ANS was due to pesticides and chemical solvents. However, these results agree with the results of pupillographical examination in Behcetís disease. The patients with Behcetís disease showed a similar dysfunction of their ANS by pupillographical analysis as seen in our patients. In the patients with Behcetís disease, pesticides and/or chemical solvents were thought to trigger the disease because, not only were pesticides and/or chemical solvents detected in the patientís blood, but symptoms increased after exposure to toxic chemicals. From this point of view, the initial stage of Behcetís disease might be similar to those of the chemically sensitive patients in this study. In fact, one wonders if chemical sensitivity might be a forerunner of Behcetís disease, which is a fixed end stage entity.

The biochemical effect of the chlorinated pesticides and chemical solvents on the ANS is not well known. However, it has been recognized for many years that chlorinated pesticides have a great affinity for the lipid-rich tissues and organs and can be deposited there for extremely long periods of time. This affinity would suggest that they would be prone to attack any lipid-rich organ of the nervous system. Indeed, the chlorinated pesticides are known to influence the mixed-function oxidase induction, nerve conduction, and synaptic transmission.5 Additionally, reports of the influence of chlorinated pesticides on brain-function reveal that chlorinated pesticides have an inhibitory or depressive effect on the central nervous system. This depressive effect might involve the hypothalamus and/or the peripheral autonomic fibers. This present study suggests that there is an inhibitory effect on some parts of the ANS in chemically sensitive patients. From these results, we may infer that the presence of chlorinated pesticides and chemical solvents in chemically sensitive patients produce an inhibitory effect on some patientís central and autonomic nervous systems.

Organophosphate pesticides inhibit acetyl-cholinesterase action at the synapse. A cholinergic condition occurs which results in an inability to deactivate acetylcholine. This would result in cholinergic reaction as measured by the iriscorder. It is generally thought that organochlorines do not act in the way organophosphates do, but they certainly show changes on the iriscorder.

When analyzing the function of the ANS in each group, the percentage of autonomic nerve disturbance was higher in the pesticide group (90.0%) than in the chemical solvent group (65%). Additionally, the significant difference was seen in the velocity of dilatation between chemical solvents patients and pesticides patients (P<.01). These results suggests that the effects of pesticides on the ANS is stronger than that of chemical solvents since the sympathetic nerve was suppressed more strongly in the chlorinated pesticides group than in the chemical solvents group. However, this inhibition may be a result of total chemical load phenomenon in which more unmeasured chemicals were involved. All the chemicals in these patients were not studies, therefore, one can only speculate on the total load.

In ten out of forty-three patients, there was no pupillary reaction abnormality, yet the patients had some symptoms of ANS dysfunction. One reason that might explain this observation is that they did not have a disturbance of the autonomic nerve which was related to the eye. The pupillographical examination method reflects the autonomic nervous function of the head very well, but may not measure all the effects on other parts of the body. The other reason is that the patients may not have been stimulated by the present chemical load over and above their own biological reaction i.e. norepinephrine or other biochemical. The system may have been temporarily balanced with a new set point of adaptation, resulting in no triggering of the autonomic nervous system. The timing of measurement and an incitant challenge may be necessary to show objective changes in these patients, and the exact time of change may have been missed. In these patients, de-adaptation for four days with reduction of the total body load in order to achieve reproducible information may have to be done. Finally, though highly unlikely, the patient may not have ANS involvement.

In the distribution of the type of autonomic nerve disturbance (Table 3), the sympatholytic type, which caused by inhibition of the sympathetic nervous system, was seen in 21 out of 33 patients (63.6%). This result agrees with the results of Table 1 which shows that pesticide and chemical solvent patients have a hypofunction of the ANS as already described. However, the percentage of the cholinergic type (27.3%) which is caused by stimulation of the parasympathetic nervous system was much higher than that of cholinolytic type (6.1%). The reason for this is unclear. Seven of nine patients who had a cholinergic response belonged to the pesticide group. Five out of seven patients with pesticide in their blood had the experience of using organophosphate in addition to organochlorine pesticides for one or two years previously, which possibly could account for the stimulation effects. However, this generally is a long time after an acute exposure to see stimulation effects. In these five patients who had the experience of using the organophosphate pesticides, the residue level of organophosphate pesticide was not detected in their blood, However, since their pupillary responses suggested the influence of organophosphate pesticides, one can speculate that the original exposure may have resulted in a weakness in the cholinesterase system. The amount of daily inhaled or ingested organophosphate pesticides contained in ambient air and food might then account for chronic cholinergic triggering. In addition, it is known that some organochlorines will give stimulation of the central nervous system, and may well explain the cholinergic stimulation in these patients. The sympathomimetic type response, which is caused by stimulation of the sympathetic nerves, was seen in only one out of thirty-three patients. This results might be due to the time of measurement (since the duration from an initial exposure of chemicals is an important factor in chemical reactions) or the fact that they were not stimulated.

It is known that an initial exposure of chemicals stimulates or suppresses the activity of the immune system in chemically sensitive patients.9 Recurrent exposure of chemicals usually suppresses the immune system activity. In chemically sensitive patients, their autonomic nervous systems might be stimulated just after an initial exposure of chemicals. However, the time of measurement of these patients was done after several exposures of chemicals, therefore, their ANS functions probably were usually suppressed, like their immune systems.

CONCLUSION

From this study, twenty-three patients (69.7%) showed inhibition of their ANS against ten patients (30.3%) who showed stimulation. The results suggest that the overload of chlorinated pesticides and the chemical solvents in the chemically sensitive patient usually act as inhibitory substances on the sympathetic fibers of the autonomic nervous system, but a stimulating effect on the parasympathetic nervous system. In the future, we should elucidate the progress of ANS function in correlation to the total body loads and the time factor. It is clear, however, that the patients with chemical sensitivity who have toxic chemicals in their blood have some type of autonomic nervous system dysfunction which can be objectively measured by pupillography when performed in a less polluted environment.