Letters to the Editor

Treatment of severe dry eye SIR—Dry eye syndrome ranges widely in severity from ocular fatigue associated with the use of video display terminals (VDTs) to the destructive changes seen in advanced StevensJohnson syndrome (SJS) or ocular cicatricial pemphigoid (OCP).1 Whereas patients using VDTs never lose vision, those with OCP frequently go blind. In SJS or OCP, the cornea becomes opaque from vascularisation and is covered by conjunctival epithelium due to depletion of corneal stem cells.2 The absence of even reflex tears3 makes these diseases contraindications to corneal transplantation. Since tears supply factors such as epidermal growth factor and vitamin A that are essential for the proliferation and maturation of the corneal epithelium, the cornea cannot survive without tears. We have developed a surgical technique for ocular surface reconstruction in SJS and OCP. We carried out corneal limbus transplantation to replace the corneal epithelial cells, and provided, for frequent use, autologous serum drops as artificial tears to supply growth factors and vitamin A.4,5 Although the initial observation period was short, this approach seemed promising. We report here the 18-month follow-up of a patient with SJS who responded well to our treatment. A 37-year-old woman had severe SJS 7 years ago and gradually developed cicatricial keratoconjunctivitis. The left cornea became opaque and keratinised (upper figure); visual acuity was 30 cm for hand motion on Oct 3, 1994. Tear

function was completely lost, with no reflex tears. We carried out corneal limbal allograft transplantation and tarsorrhaphy on Oct 13, 1994, and then provided, for frequent use (every 15 min), autologous serum drops. The corneal epithelium was re-established in 2 weeks and visual acuity recovered. Since the Schirmer test, even with nasal stimulation, yielded 0 mm during the initial observation period, autologous serum drops were continued 10 times a day. Low-dose cyclosporin (75 mg/day) was maintained. The corneal epithelium remained clear without any keratinisation or vessel invasion (lower figure), with a final visual acuity of 20/30, with ⫺1·25 D of astigmatism, on March 14, 1996. This report demonstrates the feasibility of combining corneal epithelial stem-cell transplantation with autologous serum drops to treat severe dry eye, such as in SJS or OCP. Our case suggests that serum components can induce proliferation and differentiation of the corneal epithelium, even in the absence of endogenous tear production. *Kazuo Tsubota, Yoshiyuki Satake, Jun Shimazaki *Department of Ophthalmology, Tokyo Dental College, Chiba, Japan 272; and Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan

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Mondino B, Brown S. Ocular cicatricial pemphigoid. Ophthalmology 1981; 88: 95–100. Puangsrocjare V, Tseng S. Cytologic evidence of corneal diseases with limbal stem cell deficiency. Ophthalmology 1995; 102: 1476–85. Tsubota K, Toda I, Saito H, Shinozaki N, Shimazaki J. Reconstruction of the corneal epithelium by limbal allograft transplantation for severe ocular surface disorders. Ophthalmology 1995; 102: 1486–96. Tsubota K, Satake Y, Ohyama M, et al. Surgical reconstruction of the ocular surface in advanced ocular cicatricial pemphigoid and StevensJohnson syndrome. Am J Ophthalmol (in press). Tsubota K, Xu K, Fujihara T, Katagiri S, Takeuchi T. Decreased reflex tearing is associated with lymphocytic infiltration in lacrimal glands. J Rheumatol 1996; 23: 313–20.

Relation between Glasgow Coma Scale and aspiration pneumonia

Figure: Preoperative (top) and postoperative (bottom) slit-lamp photographs

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SIR—Decreased level of consciousness is associated with increased risk of gastric aspiration.1 The risk of aspiration is, however, unquantified with regard to the degree of impaired consciousness. Accordingly, emergency airway management by endotracheal intubation is practised in accordance with perceived risk of aspiration pneumonia in comatose patients. A few studies have addressed the relation between gag reflex, cough reflex, and the Glasgow Coma Scale (GCS) in patients with pharmacological causes for cerebral depression.2,3 Both of these reflexes provide protective mechanisms against aspiration of gastric contents. These authors demonstrated that the correlation between the GCS and the presence of protective reflexes is poor. The cough reflex was still present (normal or attenuated) in seven of 12 patients at the lowest level of GCS (GCS 3). In contrast, the gag reflex may be impaired even at high GCS values.2,3 A GCS of 8 or less is widely accepted to indicate protection of the airway by intubation.4 We undertook a prospective study designed to assess the relation between degree of impaired consciousness, as defined by GCS at the time of patient discovery by prehospital care personnel, and frequency of suspected aspiration pneumonia on admission to the intensive care unit. Aspiration pneumonia was defined by analysis of the chest radiographs taken within the first 24 h.

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All consecutive drug-poisoned patients who were admitted to our toxicological intensive care unit were included. The GCS score in the prehospital phase, before intubation and sedation, was measured. Patients were included in the aspiration suspected group if a localised and evocative infiltrate was found on the chest radiographs in the first 24 h after admission. Patients were included in the no suspected aspiration group if the chest radiograph during the same period was normal. 224 consecutive patients were included. The initial GCS and frequency of inclusion in the aspiration suspected group are summarised:

GCS

Number with aspiration suspected

Number without aspiration suspected

15 (n=34) 14 (n=17) 13 (n=10) 12 (n=11) 11 (n=8) 10 (n=13) 9 (n=9) 8 (n=9) 7 (n=18) 6 (n=30) 5 (n=23) 4 (n=9) 3 (n=33)

0 1 0 3 1 3 2 4 6 13 9 6 17

34 16 10 8 7 10 7 5 12 17 14 3 16

No abnormal chest radiographs were found in patients with GCS 15. As in previous studies, we found an increasing frequency of suspected aspiration pneumonia in patients with GCS of 8 or below (55/122, 45%). However, among patients with GCS above 8 and below 15, 14·7% (10/68) had radiographic evidence of aspiration pneumonia. These ten patients represent 15·4% (10/65) of the total number with suspected aspiration pneumonia. We believe that values of GCS of 8 or below should not be considered as essential for increased risk of gastric aspiration in comatose patients. Airway management in poisoned patients should take into account the risk of aspiration pneumonia even in the presence of high GCS values. *Frédéric Adnet, Frédéric Baud Réanimation Toxicologique, Service du Pr C Bismuth, Hôpital Fernand Widal, Université Paris VII, 75475 Paris, France

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Huxley EJ, Viroslav J, Gray WR, Pierce AK. Pharyngeal aspiration in normal adults and patients with depressed consciousness. Am J Med 1978; 64: 564–68. Moulton C, Pennycook AG. Relation between Glasgow coma score and cough reflex. Lancet 1994; 343: 1261–62. Moulton C, Pennycook AG, Makower R. Relation between Glasgow coma scale and the gag reflex. BMJ 1991; 303: 1240–41. Gentleman D, Dearden M, Midgley S, Maclean D. Guidelines for resuscitation and transfer of patients with serious head injury. BMJ 1993; 307: 547–52.

Late whiplash syndrome SIR—The scope as well as the design of Schrader and colleagues’ investigation (May 4, p 1207)1 is signalled by the title: natural evolution of late whiplash syndrome outside the medicolegal conflict. Natural is defined as circumstances in which “economically motivated symptom presentation and expectation of disability is negligible”. This is found in Lithuania where “few car drivers and passengers are covered by insurance, and there is little awareness among the general public about the potentially disabling consequences of a whiplash injury”. Schrader and colleagues raise serious doubts as to whether whiplash accidents lead to chronic symptoms, seen as caused by expectation of disability and attribution of pre-existing symptoms to the trauma. The issue is considerably more difficult than this report can resolve.

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The main difficulty is patient selection. The questionnaire participants were drivers of cars with serious rear-end impacts of such magnitude that traffic police were called to the scene. Since in Lithuania very few drivers have car insurance, police are usually called upon to evaluate the damage. By comparison, in Norway police are called only when there is personal injury. In Norway about 6000 persons per year are injured in rear-end impacts, but the organisation for insurance companies recorded many more rear-end accidents (42 208 in 1994). The type of register from which the sample is selected determines what type of comparison can be made and what conclusions can be drawn. If we judge the Norwegian insurance records to be mostly in accordance with the Kaunas police register, a very large part of the population, perhaps half, may be recorded in this register during a lifetime of driving. Schrader and co-workers’ finding of no difference between a sample of 202 from this population and 202 from the Lithuanian population, with respect to neck pain, headache, &c is hardly surprising. Nor is the finding unexpected that none of the accident victims had persistent or disabling symptoms caused by car accidents with such a small and unspecified sample. Whatever type of register—police, insurance companies, or hospital emergency departments—people would have to be classified on the basis of information about the accident, as well as of medical investigations, before differences in group data could be expected. Schrader and colleagues’ study was based on information only from drivers. Among the 172 drivers there were only 15 women. Since persistent symptoms after whiplash are most likely among women and passengers, this bias also reduces the chances of showing any group differences. Late in the study 30 female passengers were recruited, but this group was aware of the reason for the study, unlike the earlier participants. The introduction of compulsory use of safety belts led to a reduced death rate from rear-end impact, but to a rise in typical whiplash syndrome. In Lithuania, up to now, safety belts have been used less than in Norway. The relative proportion of death rate/whiplash rate might change in Lithuania, but the absence of statistical information reduces the chances of making meaningful comparisons between the two countries. No such study takes place in a sociological vacuum. After half a century of occupation, Lithuanian people have learned to be sceptical about giving out information that may be used against them. When asked if they were using safety belts at the time of the accident, many informants might not have admitted that they were not, for fear of being penalised, despite inducement to tell the truth. In general, it is very risky to draw conclusions based on a questionnaire with no control and no objective measurement or medical investigations. Schrader and colleagues’ study is interesting as a research idea, but it should also be methodologically valid. The conclusions drawn from this study can hardly be justified by the data. They remain personal, unproven beliefs. Ivar A Bjørgen Institute of Psychology, University of Trondheim, 7055 Trondheim, Norway

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Schrader H, Obelieniene D, Bovim G, et al. Natural evolution of late whiplash syndrome outside the medicolegal context. Lancet 1996; 347: 1207–11.

SIR—We question the wisdom of Schrader and colleagues1 in doing a case-cohort study on whiplash-associated disorders due to rear-end collisions in a population in whom the prevalence of whiplash is low. First, a case-cohort study has the potential to detect valid causal relations if based on a proper knowledge of background. However, since the Quebec Task Force on

Vol 348 • July 13, 1996