What causes Horner's syndrome

Horner's syndrome is an eye disease caused by nerve damage. The main manifestations of the disease are constricted pupils and drooping eyelids, but the response to light is normal. The eyeball appears sunken, and there is no sweating on the forehead on the same side of the affected eye. Currently, when treating Horner's syndrome, treatment is directed at the cause of the disease, and the medication used is also determined based on the patient's condition and cause. In general, after treatment, the patient's symptoms will be relieved after a few weeks. Now let's talk about the causes of Horner's syndrome.

Reason 1

The most common cause of Horner syndrome is cervical artery dissection, which can occur spontaneously or as a result of local trauma to the neck. Background: Chiropractic care is an independent risk factor for internal carotid artery (ICA) dissection and stroke, a topic of controversy. There have been several reports of Horner syndrome caused by ICA dissection due to spinal massage. ICA dissection was not considered in this patient because the patient also had significant radiating brachial plexus pain, and CT angiography of the neck ruled out the possibility of dissection.

Reason 2

The absence of facial anhidrosis is a sign of a postganglionic or preganglionic sympathetic focus on the T1 nerve root, as the sudomotor fibers separate from the carotid plexus at the level of the carotid bifurcation and are present in the spinal cord at the T2-T3 segment level. Therefore, attention should be paid to the rare case of partial Horner syndrome due to lesions at the level of the T1 nerve root, as in this patient.

Reason 3

The simultaneous occurrence of Horner syndrome and symptoms such as pain and weakness in the ipsilateral upper limb meets the diagnostic criteria for superior pulmonary sulcus tumor syndrome, suggesting that malignant tumors at the apex of the lung may involve both the sympathetic trunk and the lower trunk of the brachial plexus. However, a lung X-ray ruled out lung lesions. Subsequent neurophysiological studies revealed normal SAP of the medial forearm cutaneous nerve, consistent with a preganglionic radicular lesion, which was also confirmed by MRI. If the superior pulmonary sulcus tumor involves the inferior trunk of the brachial plexus, SAP should be weakened or disappear.

Reason 4

Pupillary drug testing can be used to confirm the presence of Horner syndrome and help localize lesions in the oculosympathetic pathway. Cocaine, a norepinephrine reuptake inhibitor, will not induce a pupillary dilation response if used in patients with loss of sympathetic innervation of the iris dilator muscles, confirming the presence of Horner syndrome.

Reason 5

On the other hand, local injection of hydroxyphenylethylamine can cause pupil dilation by promoting the release of adrenaline from presynaptic nerve terminals. This reaction occurs only when the postganglionic neurons (third-order neurons) are intact and can therefore be used to differentiate between central, preganglionic, and postganglionic lesions.

Reason 6

Central Horner syndrome is caused by a stroke in the brainstem, such as Wallenberg syndrome. It is rarely confused with peripheral etiologies because it is often accompanied by other findings suggestive of brainstem injury, including nystagmus, dissociated sensory disturbances, and ipsilateral cerebellar symptoms.