Positive Apraclonidine Test in Horner Syndrome Caused by Thalamic Hemorrhage

Cortico-hypothalamic pathway of Horner syndrome derived from isolated lenticulostriate stroke

BACKGROUNDS

Horner syndrome presents with ipsilateral ptosis, miosis, and anhidrosis due to interruption of the oculosympathetic pathway. Patients with acute ischemic stroke may present with Horner syndrome, which may help locate the lesion. However, the underlying pathways involved in Horner syndrome caused by isolated lenticulostriate ischemic stroke remain unclear.

METHODS

We screened consecutive patients with acute ischemic stroke admitted to the Second Affiliated Hospital of Guangzhou Medical University from 1 January 2020 to 31 December 2021, and searched for cases of isolated lenticulostriate strokes presenting with Horner syndrome. Strokes involving the brainstem or hypothalamus, or those caused by carotid dissection or carotid cavernous fistula were excluded based on neuroimaging and cerebrovascular examination.

RESULTS

Among the 1706 acute stroke patients, three patients developed temporary or long-term Horner syndrome due to an ipsilateral lenticulostriate ischemic lesion. Diffusion-tensor imaging revealed disruption of an uncrossed pathway from Brodmann areas 3, 1, and 2 through the basal ganglia to the ipsilateral hypothalamus.

CONCLUSION

These findings suggest that Horner syndrome may be due to a disruption of an uncrossed cortico-basal ganglia-hypothalamic sympathetic pathway.

Apraclonidine for the pharmacologic confirmation of acute Horner syndrome

Apraclonidine is the most widely used pharmacologic agent to confirm Horner syndrome. It is a strong α-2 and a weak α-1 adrenergic agonist and reversal of anisocoria is considered a positive test. The utility of apraclonidine in acute Horner syndrome remains controversial as the exact timing for denervation sensitivity to develop remains unknown. The goal of this study was to describe the use of apraclonidine in the diagnosis of acute Horner syndrome in patients with an unequivocal onset within 7 days. We identified 3 patients who were referred to ophthalmology/neuro-ophthalmology service and had reversal of anisocoria within 7 days. Two cases of second-order Horner syndrome after cardiac surgery and a case of a third-order Horner syndrome from a carotid cavernous sinus fistula resulted in reversal of anisocoria 72 h, 48 h, and 5 days after onset. Photographic documentation was provided for all cases. Our results suggest that apraclonidine has utility in the acute period and positive results can be seen as early as 48 h after onset. Apraclonidine should therefore still be considered to confirm the presence of acute Horner syndrome before extensive neuroimaging is performed.

Horner Syndrome as the Only Focal Neurologic Manifestation of Hypothalamic Hemorrhage

A 70-year-old woman suffered an anterior dorsal hypothalamic hemorrhage that caused an ipsilateral Horner syndrome (HS) as the only focal neurologic manifestation. This is only the second reported case of hypothalamic hemorrhage producing HS. Because HS was the sole focal neurologic manifestation, its confirmation with topical apraclonidine drops was a valuable clue toward prompt localization of the patient's confusional state.

Efficacy of digital pupillometry for diagnosis of Horner syndrome

Objectives

To evaluate the efficacy of digital pupillometry in the diagnosis of anisocoria related to Horner syndrome in adult patients.

Design

Retrospective, observational, case control study.

Methods

Nineteen patients with unilateral Horner syndrome (Horner group) and age-matched controls of 30 healthy individuals with normal vision and neither optic nerve dysfunction nor pupillary abnormalities were included. Pupillary light reflex (PLR) of the Horner group and controls were measured by a dynamic pupillometer (PLR-200; NeurOptics Inc., Irvine, USA). Minimal and maximal (min/max) pupil diameters, latency, constriction ratio, constriction velocity, dilation velocity, and total time taken by the pupil to recover 75% of maximal pupil diameter (T75) were noted. PLR were measured at baseline in both groups and at 30–45 minutes later after 0.5% apraclonidine (Iopidine^®; Alcon Laboratories, Fort Worth, TX, USA) instillation in the Horner group.

Main outcome measures

The PLR parameters in the affected eye and inter-eye difference before and after 0.5% apraclonidine instillation.

Results

In the Horner group, pupil diameters and T75 showed significant difference between the affected eye and unaffected contralateral eye at baseline (all P<0.00625). Compared to controls, inter-eye difference values of pupil diameters and T75 were significantly larger in the Horner group (all P<0.001). After 0.5% apraclonidine instillation, changes in pupil diameter and constriction ratio were significantly larger in the affected eye compared to the unaffected contralateral eye (all P<0.00625). The area under the receiver operating characteristic curves for diagnosing Horner syndrome were largest for baseline inter-eye difference in min/max pupil sizes (AUC = 0.975, 0.994), T75 (AUC = 0.838), and change in min/max pupil sizes after apraclonidine instillation (AUC = 0.923, 0.929, respectively). The diagnostic criteria for Horner syndrome relying on baseline pupillary measurements was defined as one of the two major findings; 1) smaller maximal pupil diameter in the affected eye with an inter-eye difference of > 0.5 mm, or 2) T75 > 2.61 seconds in the affected eye, which showed a sensitivity of 94.7% and specificity of 93.3%. The diagnostic accuracy of apraclonidine testing showed a sensitivity of 84.6% and specificity of 92.3%.

Conclusions

Digital pupillometry is an objective method for quantifying PLR. Baseline inter-eye difference in maximal pupil sizes and dilation lag measured by T75 was equally effective in the diagnosis of Horner syndrome compared to the reversal of anisocoria after apraclonidine instillation.