Unilateral orthostatic headache caused by glaucoma

Orthostatic headache, a prototypical manifestation of low cerebrospinal fluid (CSF) pressure syndrome (1–3), has also been reported in a type I Chiari malformation (4), cerebellar haemorrhage (5), skull base and cervical spine tumour (6, 7), postural tachycardia syndrome (8) and filum terminale ependymoma (9). However, orthostatic headache has never been reported as a presenting sign of glaucoma. Here, we report an angle closure glaucoma patient whose presenting sign was unilateral orthostatic headache.

Case report

A 47-year-old man was referred to an outpatient clinic due to a newly developed unilateral headache that lasted for 5 days. The headache was mainly compressing and dull in nature. It was accompanied by intermittent electrical shock pain of moderate to severe intensity (visual analogue scale = 7), which was strictly localized to the left ocular, periorbital and frontal areas. Interestingly, the 5- to 10-min attacks presented only when the patient was in an upright or sitting posture. The pain completely resolved 10–15 s after supine positioning. During an attack, the patient claimed to experience no other symptoms, such as nausea, vomiting, photophobia or phonophobia. Nor did autonomic symptoms, including lacrimation, conjunctival injection, rhinorrhoea, facial swelling, ptosis and Horner syndrome, accompany the attacks.

The patient had no prior history of headache, but for several months he had experienced dizziness and palpitation in the upright posture. He had long suffered from diabetes mellitus complicated by nephropathy, neuropathy and retinopathy. Although he had received panretinal photocoagulation treatment, his visual acuity had decreased in both eyes (finger count only in the left eye and 20/200 in the right eye) over the previous several years. The patient denied recent deterioration of sight. Neurological examination demonstrated decreased tendon reflexes and impaired position sensation in all extremities. The pupil size and direct and indirect light reflex were normal. Other results were unremarkable.

Magnetic resonance imaging evaluation showed that the retro-orbital area, cavernous and sphenoidal sinuses, cerebral parenchyme, subdural spaces and ventricles were normal. There was no vascular malformation or abnormality revealed by magnetic resonance angiography. A tilt table test demonstrated a significant drop in blood pressure (systolic 80 mmHg and diastolic 50 mmHg) and subsequent increment of heart rate of > 20 bpm within 2 min after a tilt of 80°.

The patient took tramadol 37.5 mg and paracetamol 325 mg twice a day. Despite the medication, the severity of the orthostatic headache progressed during evaluation. Five days after initial evaluation, the pain also occurred in the supine position, and conjunctival injection developed in the left eye. Orthostatic features had continued. Prompt ophthalmological examination showed increased intraocular pressure (IOP) in the left eye (60 mmHg in the left eye vs. 16 mmHg in the right eye). After the administration of mannitol, his headache partially improved.

Slit-lamp examination, including gonioscopy, demonstrated a narrowing of the irido-corneal angle in the left eye due to the growth of a fibrovascular membrane over the trabecular meshwork. He was diagnosed in the left eye with secondary angle closure glaucoma due to diabetic neovascularization. Within 3 days after glaucoma drainage implant surgery (Ahmed valve), his headache resolved completely and did not recur during 5-month follow-up.

Discussion

Our patient was diagnosed with a unilaterally localized orthostatic headache due to glaucoma. Usually, orthostatic headache associated with CSF leaks has been described as gradually progressing, diffuse, and dull and compressing pain in the bilateral frontotemporal, occipital, or neck areas (1–3). However, in a few cases orthostatic headache resulting from some aetiologies began and persisted for some time in a strictly unilateral fashion before generalization (5,6). In the present case, the patient had a strictly localized orthostatic headache in the left orbital, periorbital and frontal areas, suggesting a secondary cause.

The diagnosis of glaucoma in our patient was delayed until the ‘red eye’ developed. In acute angle closure glaucoma, the orbital pain and headache are usually accompanied by chemosis, protective ptosis, poor vision, and mid-dilated and poor-reactive pupils (10). ‘Red eye’ had long been considered a prognomic sign of glaucoma and a key clue to differentiate eye disease from migraine or trigeminal autonomic cephalalgias. However, this has been abandoned as myth. It has been reported that subacute and intermittent angle closure glaucoma may not present with the typical eye signs, such as red eye (11,12). This has consequently led to misdiagnosis and treatment failure (10–13). Sometimes, it is challenging to differentiate the pain in subacute or intermittent angle closure glaucoma from another headache syndrome. One study that investigated headache associated with subacute angle closure glaucoma suggested that the correct diagnosis of glaucoma took about 2 years (11). Therefore, ophthalmological examinations are needed in all cases of retro-orbital pain (11,12).

The present patient showed orthostatic eye pain due to glaucoma. It has been reported that the pain of glaucoma could be triggered or aggravated by pupil dilation caused by darkening or hypersympathetic states (10) and by prone position (11). In considering the mechanism to explain our patient's orthostatic eye pain, we presumed that upright mydriasis could exacerbate increased IOP. As our patient already had a narrow irido-corneal angle due to severe neovascularization, sudden orthostatic mydriasis may have resulted in the closure of the iridocorneal angle and prohibited the outflow of aqueous humour. Our patient has severe orthostatic hypotension due to diabetic autonomic neuropathy. It has been reported that orthostatic intolerance in diabetes could be divided into two categories, ‘hyperadrenergic’ and ‘hypoadrenergic’ presentation (12–14). Our patient complained of orthostatic dizziness and palpitation with a significant drop in blood pressure and compensatory tachycardia demonstrated by the tilt table test. His orthostatic intolerance was thought to be a ‘hyperadrenergic’ presentation, hence associated with orthostatic mydriasis.

The present case emphasizes that subacute or intermittent angle closure glaucoma could also induce orthostatic headache. With a lack of evidence for intracranial hypotension, especially when the headache is strictly localized around unilateral orbital and periorbital areas, a detailed history and prompt ophthalmological examination are needed for the differentiation of glaucoma.