Rare, But Not Impossible

The term optic disc edema refers to swelling of the optic disc, along with a simultaneous buildup of fluid within or surrounding the axons. Although unilateral disc edema is more prevalent, bilateral disc edema can also occur. In the context of bilateral versus unilateral optic nerve head swelling, the most probable etiological categories consist of increased intracranial pressure (ICP), infectious/inflammatory origins, demyelinating disorders, toxic metabolic/nutritional influences, malignant hypertension, and a brain space-occupying lesion.

Pinealoma is a term traditionally used to describe both pineal parenchymal tumors and germinomas, which represent the predominant classifications of primary pineal region tumors. It is not uncommon for pineal region lesions, especially smaller ones, such as cysts that demonstrate minimal changes in size, to be incidentally detected. Conversely, patients with larger lesions typically experience clinical symptoms that are directly attributable to the mass effect.

Pineal cysts are predominantly small in size, usually less than 1 cm, and are often asymptomatic; however, these cysts can exert pressure on the tectal plate when they increase in size, causing compression of the superior colliculi and resulting in Parinaud syndrome. Compression of the cerebral aqueduct by these cysts can lead to obstructive hydrocephalus.

CASE REPORT

A 14-year-old white female presented for a routine eye exam. She had a history of occasional headaches and psychiatric symptoms and was experiencing sinusitis. She had no medical or surgical history, no known drug allergies, and was not taking any medications. Her BMI was 20 k/m².

The patient’s BCVA was 20/20 OU, and the Ishihara color plates test indicated a score of 14/14 OU, along with an asymmetrical red cap test. Pupil examination revealed normal findings, with no presence of anisocoria or afferent pupillary defect. Extraocular movements were normal. Confrontational visual fields were found to be full without any restriction. Additionally, IOP was 17 mm Hg OU. Retinal examination revealed no notable abnormalities, except for bilateral grade 2 papilledema that was characterized by blurred and elevated disc margins. Neurologic examination was unremarkable.

IMAGING AND DIAGNOSTIC WORKUP

OCT revealed an average retinal nerve fiber layer of 110 µm OD and 106 µm OS, with a clean 30-2 visual field extending a full 360°. MRI displayed a subcentimeter complex pineal cyst with thin mural enhancement, along with a 7 mm x 9 mm enhancing nodule located posteriorly (Figure). Postcontrast imaging revealed no abnormal enhancement in the parenchymal, leptomeningeal meningeal, or pachymeningeal areas. The patient’s brain was morphologically normal. There was no empty sella morphology. The pituitary gland was normal in size for the patient’s age/demographic. There was no regional mass effect, midline shift, or hydrocephalus. ICP was measured at 19 mm Hg with the patient in a supine position. Normal ICP is typically between 7 mm Hg and 15 mm Hg. Upon confirmation of papilledema via fundoscopic examination, order a brain MRI to rule out a space-occupying lesion as the underlying etiology. Idiopathic intracranial hypertension is another potential cause of optic nerve edema and should be evaluated with a lumbar puncture.

The beta-human choriogonadotropin tumor marker was found to be below 1, and the alpha-fetoprotein level was less than 0.8 ng/ml. Additionally, the patient’s cerebrospinal fluid (CSF) tested negative for malignant cells; however, there were moderate Gram-positive cocci, and a small number of Gram-negative rods were observed. The CSF glucose level was 55 mg/dl, with a protein level of 15 mg/dl and 46 red blood cells per microliter. The tests for antinuclear antibody, CSF Lyme, angiotensin-converting enzyme, anti-acetylcholine receptor antibodies, and anti-muscle-specific kinase yielded negative results.

The patient’s blood work was unmarkable, except for her vitamin B12 level, which was 366 pg/ml. Subsequently, the patient started a course of oral vitamin B12 supplementation at a dosage of 1,000 mcg for approximately 6 months. After 9 months, a follow-up brain and orbit MRI scan was performed, both with and without contrast. The results of the scan indicated no alteration in the size of the pineal gland cyst, and the optic nerve heads appeared normal. Additionally, the patient’s family reported an improvement in her psychiatric symptoms.

Upon subsequent evaluation 3 months later, the patient reported a significant improvement in her headaches. She did not report any additional visual or neurologic symptoms. The follow-up assessment demonstrated a BCVA of 20/20 OU, along with a reduction in optic nerve head edema, as observed during fundus examination. However, OCT of the retinal nerve fiber layer thickness remained unchanged after the lumbar puncture. Automated visual field testing using the 30-2 protocol yielded normal results.

DISCUSSION

This case illustrates the occurrence of papilledema resulting from a minor increase in ICP despite remaining within the upper limit of normal values. Notably, the papilledema was not associated with a pineal gland lesion, as the lesion’s size was less than 1 cm and did not display any signs of a substantial mass-occupying lesion. However, a study evaluating patients with large intracranial tumor with absence of papilledema reported that the progression of papilledema is determined by the existence of heightened ICP and the conveyance of this pressure to the subarachnoid space surrounding the optic nerve sheath and the optic nerve itself.¹

Contamination of CSF can occur during a lumbar puncture if the proper aseptic technique is not used, potentially causing delays in diagnosis and resulting in the administration of incorrect medication. Taking into consideration the normal CSF glucose and protein levels, and the presence of red blood cells and Gram-positive and Gram-negative bacteria, the occurrence of bacterial meningitis is highly unlikely. Research revealed that increased blood contamination in CSF results in inaccurately elevated levels of CSF protein.²

Sinus infections are a known factor in the development of idiopathic intracranial hypertension; however, such cases are infrequent and have only been rarely reported.³

Although the patient’s cobalamin level was within normal range (200 - 1,100 pg/mL), it has been documented that a subset of patients with values between 200 - 400 pg/mL may encounter neuropsychiatric abnormalities due to occult B12 deficiency, including myelopathy, neuropathy, dementia, and, in rare instances, optic nerve atrophy, prior to the appearance of hematologic indications.⁴ The total plasma cobalamin level, therefore, may not serve as a reliable marker for vitamin deficiency.⁵

CAUSE AND EFFECT

This case presents an exceptional instance of mild idiopathic intracranial hypertension due to sinusitis linked to hidden vitamin B12 deficiency and a pineal gland lesion, which were successfully treated with vitamin B12 supplementation and a spinal tap, respectively, without need for a carbonic anhydrase inhibitor.