Astigmatoma: Pineal Germinoma Presenting as Parinaud Syndrome Initially Misdiagnosed as Astigmatism

This case report describes a 24-year-old male whose blurry vision and difficulty reading were initially attributed to astigmatism and treated with corrective glasses followed by bilateral LASIK surgery, before a neuro-ophthalmic examination revealed Parinaud syndrome caused by a large pineal gland germinoma. The study was published in the Journal of Ophthalmology and Research in 2021. It serves as a critical reminder that difficulty focusing may arise from neurological disease rather than simple refractive error.

Background

Parinaud syndrome (dorsal midbrain syndrome) presents with abnormal ocular motility and pupil dysfunction caused by lesions affecting the dorsal midbrain. The classic triad consists of upgaze paralysis, pupillary light-near dissociation, and convergence retraction nystagmus. Patients may express difficulty focusing on words while reading, experience jumping letters, complain of diplopia, difficulty looking up, and blurred near vision.

The etiology of Parinaud syndrome varies by age. In children and young adults, neoplastic causes are most common, while in older adults, vascular disease predominates. Pineal gland tumors are the most frequent cause overall, though other midbrain pathologies such as vascular abnormalities, hemorrhage, or infarction can also be responsible.

Germinomas are a type of germ cell tumor that most commonly arise in the pineal region. They are highly sensitive to radiation and chemotherapy, and long-term survival with low-dose radiotherapy alone has been promising. However, early diagnosis is essential, as delays can lead to tumor progression and surgical complications.

The Patient

A 24-year-old Hispanic male presented with the following clinical timeline:

• January 2019: Noticed blurry vision and inability to focus on words while reading
• Initial treatment: Prescribed astigmatism corrective glasses -- remained symptomatic
• March 2019: Underwent bilateral LASIK surgery for presumed refractive error
• One month post-LASIK: Symptoms worsened with new development of nystagmus and double vision
• Neuro-ophthalmology referral: Presented with the classic triad of Parinaud syndrome

The patient's past medical and surgical history were otherwise insignificant, and he was not taking any medications prior to presentation.

Diagnostic Workup

Neuro-Ophthalmic Examination

• Parinaud syndrome triad identified:
  • Collier lid retraction (bilateral upper eyelid retraction)
  • Limitation of elevation (upward gaze palsy -- patient could not look up)
  • Convergence retraction nystagmus
• Pupillary examination: Light-near dissociation (pupils constrict to near targets but not to light)
• Complaint of mild headaches
• Normal findings: Visual acuity, color vision, fundus exam, visual field, and OCT of the optic nerve were all within normal limits

Neuroimaging

• MRI brain revealed a large posterior midbrain tumor involving the pineal gland
• The lesion was circumscribed and slightly lobulated
• Prominent diffuse contrast enhancement on T1-weighted post-contrast images in axial, coronal, and sagittal views
• Surrounding edema was present around the tumor

Histopathology

• Biopsy confirmed the diagnosis of pure germinoma
• Microscopic findings: Nests of neoplastic cells separated by fibrous bands and lymphocytes (H&E stain, 200x magnification)

Findings

Surgical Outcome

• The patient underwent surgical resection of the tumor
• Intraoperative complication: Bleeding during surgery resulting in hemiparesis
• Post-surgical plan: Neurosurgery/Oncology team planned cranioplasty followed by decannulation and subsequent radiation therapy

Differential Diagnosis Considerations

The case highlights the importance of considering midbrain pathology in the differential diagnosis of reading difficulty:

• Refractive errors (astigmatism, myopia, hyperopia)
• Convergence insufficiency
• Dorsal midbrain lesions (tumors, vascular malformations, hemorrhage)
• Pineal gland tumors including germinoma, pineocytoma, pineoblastoma

Clinical Significance

This case carries several critical lessons for both general ophthalmologists and neuro-ophthalmologists:

• Reading difficulty is not always refractive: Any complaint of difficulty focusing on letters at near should prompt a thorough motility and pupillary exam, not just refraction
• LASIK did not address the underlying problem: The persistence and worsening of symptoms after refractive surgery was the signal that a neurological cause was being missed
• Germinoma in young adults: Germinoma should be considered in the differential diagnosis of midbrain lesions in young adults. MRI-guided stereotactic biopsy provides critical diagnostic information
• Multidisciplinary care is essential: Treatment of Parinaud syndrome requires coordination between neurosurgery, pathology, ophthalmology, and oncology
• Prognosis depends on early diagnosis: Long-term survival with intracranial germinoma treated with low-dose radiotherapy alone has been promising, but delayed diagnosis may lead to complications

Citation

Naser M, Hooshi P, Mortazavi M, Westfal D, Schultheis W, Hashemi N. Astigmatoma. J Ophthalmol Res. 2021;4(1):xx-xx. DOI: 10.26502/fjor.2644-00240029

References