George Riding, Mawar Zafar, Lauren Ross, David Turner

Northeast Health Wangaratta, Victoria, Australia

Case Presentation

An 80-year-old female presented with recurrent central chest pain of unclear cause that was unresponsive to glyceryl trinitrate spray; ECG demonstrated no ischaemic changes, and serial troponins were negative.

Hyponatraemia with a syndrome of inappropriate antidiuretic hormone secretion (SIADH) pattern was incidentally identified, with a serum sodium of 124 mmol/L.  She was admitted under General Medicine for hyponatraemia management and investigation of her chest pain. She had a past medical history of ischemic heart disease with a coronary artery bypass graft in 2012, type 2 diabetes mellitus, hypertension, and was a distant ex-smoker. Medication review did not identify a cause for her hyponatraemia. On examination she was clinically euvolemic, whilst a CT brain and chest radiograph were normal. During her inpatient stay the hyponatraemia was refractory to fluid restriction and urea was initiated, which eventually improved the serum sodium to 131 mmol/L. 

Later during the admission, right-sided miosis, partial ptosis and ipsilateral anhidrosis were noted, consistent with a right-sided Horner’s syndrome. The patient was unaware of these changes and, aside from chest pain on presentation which had since resolved, reported no neck pain, swelling or focal neurological symptoms. No additional signs of respiratory or neurological disease were evident on examination.

A CT chest and neck was requested, which demonstrated a 4.5 cm left perihilar mass with extensive bilateral subcarinal, mediastinal and supraclavicular lymphadenopathy. Of the extensive lymphadenopathy, a 4.7 cm nodal conglomerate with a necrotic area abutting the right subclavian artery and common carotid was identified. Bronchoscopy and biopsy confirmed Small Cell Lung Cancer (SCLC). During staging, an MRI brain and positron-emission tomography (PET) scan were negative for distant metastases, whilst the PET scan confirmed the 4.5 cm left perihilar mass consistent with a primary lung cancer and extensive thoracic lymphadenopathy.

Discussion

Horner’s syndrome is traditionally associated with superior sulcus (Pancoast) tumours, although disruption of the oculosympathetic pathway may occur at multiple anatomical levels and may be the presenting feature of serious underlying pathology. In this case, a left perihilar SCLC was associated with a contralateral Horner’s syndrome due to suspected compression of the sympathetic chain from a nodal conglomerate abutting the right subclavian artery and common carotid. Primary detection of Horner’s syndrome remains uncommon, as most cases are only identified after an underlying diagnosis has already been established (1, 2).

The classical cause of Horner’s syndrome is a Pancoast tumour, which is defined as a primary carcinoma arising in the superior pulmonary sulcus (3).  Despite this, Horner’s syndrome has a broad differential list and vigilance is required, as oculosympathetic pathway disruption can indicate serious underlying disease including stroke, carotid or cervical artery dissection and tumour (2, 4).  

A recent series reported that procedures in the neck, chest, skull base and paraspinal region are the most common cause of Horner’s syndrome when a cause is identified (1). The second most common causes are cervical carotid dissection in ophthalmologist led pharmacologically-confirmed cases, whilst tumour was the second most common cause in cases that were not pharmacologically-confirmed and diagnosed by non-ophthalmologists (1). Therefore whilst carotid dissection and apical lung mass are well-recognised causes, rarer compressive masses along the sympathetic pathway must be considered (1).

The oculosympathetic pathway comprises a first-order neurone from the hypothalamus to the spinal cord, a second-order preganglionic neurone to the superior cervical ganglion at C2-C3, and a  third-order postganglionic neurone that travels along the internal carotid artery (4). In this case, the presence of facial anhidrosis and the anatomical location of the nodal conglomerate disrupted the oculosympathetic pathway at the thoracic inlet, despite a contralateral perihilar primary tumour. This represents a rare mechanism of contralateral Horner’s syndrome due to metastatic nodal compression from SCLC.

Resolution of Horner’s syndrome features following chemotherapy supports a potentially reversible compressive mechanism, consistent with reports describing partial recovery following correction of cervical arterial insult (5).

Conclusion

Primary detection of Horner’s syndrome is uncommon, although recognition of Horner’s prompted a timely diagnosis of SCLC, underscoring the importance of Horner’s vigilance. Metastatic nodal disease should be considered alongside the classical association with Pancoast tumours. Contralateral Horner’s syndrome from metastatic compression at the subclavian–carotid junction in SCLC is exceptionally rare.  

References

1. Sabbagh MA, De Lott LB, Trobe JD. Causes of Horner syndrome: a study of 318 patients. J Neuroophthalmol. 2020;40(3):362–369.

2. Giles CL, Henderson JW. Horner’s syndrome: an analysis of 216 cases. Am J Ophthalmol. 1958;46(3 Pt 1):289–296.

3. Detterbeck FC. Pancoast (superior sulcus) tumors. Ann Thorac Surg. 1997;63(6):1810–1818.

4. Davagnanam I, Fraser CL, Miszkiel K, Daniel CS, Plant GT. Adult Horner’s syndrome: a combined clinical, pharmacological, and imaging algorithm. Eye (Lond). 2013;27(3):291–298.

5. Mayer L, et al. Local signs and symptoms in spontaneous cervical artery dissection: a single-centre cohort study. J Stroke. 2019;21(1):112–115.