The conditions or syndromes to be considered in this article are summarised in table 1. Many are seen relatively infrequently in neurological practice. Among 4000 successive outpatient referrals, pupillary abnormalities or ophthalmological syndromes accounted for 39 (table 2). More often, some of these abnormalities—for example, a tonic pupil (Holmes-Adie syndrome)—are found by chance. Sometimes the abnormality has not been previously recognised or, even worse, has been misinterpreted. Documentation of such changes is important—not necessarily towards diagnosing the patient’s complaint, but towards preventing misinterpretation of the problem in the future. In the acutely ill patient, the recognition of the syndromes of brain herniation, particularly uncal and trans-tentorial, are critical to patient care.

ARGYLL ROBERTSON PUPIL

Argyll Robertson described his pupillary syndrome in 1869. The definition should be strict otherwise a whole host of pupillary abnormalities with some degree of light-near dissociation will be so designated. The cardinal features are summarised in table 3. The pupils are not necessarily fixed to light, though they become so in the later stages. What is critical is the dissociation between the extent of the near and the light reaction. A preserved normal acuity should be included in the criteria to exclude numerous conditions in which a depression of light sensitivity—for example, caused by optic nerve disease—leads to light-near dissociation. When strictly defined in this way the condition is pathognomonic of neurosyphilis. Cases are now rare, though the recent burgeoning of cases of primary syphilis suggest that its incidence may rise in the future. The most likely site of the causative lesion is one affecting the light reflex fibres rostral to the oculomotor nucleus.¹

HOLMES-ADIE (TONIC) PUPIL

Patients with a tonic pupil tend to present (if at all) because of a difference in pupillary …