Foster Kennedy Syndrome

Excerpt

Foster Kennedy syndrome (FKS) is based on neurological signs characterized by anosmia and vision loss (central scotoma), which may be unilateral or bilateral depending on the stage of the condition. It is defined by compressive optic damage (atrophy) in one eye and contralateral papilledema, resulting from increased intracranial pressure secondary to an intracranial space-occupying lesion.

It is worth noting that the classic presentation of FKS is also found in pseudo-FKS; thus, it is of utmost importance that the attending clinician is astute in selecting and carrying out the proper examination techniques to provide an accurate diagnosis.

There are typically three types of FKS. Type 1, the most frequent form, presents with optic atrophy in the ipsilateral eye and papilledema in the contralateral eye. Type 2 is characterized by bilateral papilledema and unilateral optic atrophy. Type 3 is defined by bilateral papilledema developing into bilateral optic atrophy. The three types of FKS are caused by different stages of metastasis of brain tumors.

Pseudo-FKS has the typical presentation of optic atrophy in one eye and papilledema in the contralateral eye, similar to type 1 FKS. However, there is no underlying compressive pathology in pseudo-FKS. Causes of pseudo-FKS include optic nerve compression by the gyrus rectus, diabetic papillopathy, and unilateral optic nerve hypoplasia.

Meningiomas (See Figures of computerized tomography scans of frontal-temporal meningioma and frontal-sphenoidal meningioma) are space-occupying tumors originating in the central nervous system. The term refers to specific disorders of the pia, dura, and arachnoid layers encapsulating the brain. They can either be cancerous or non-cancerous. The common sites for occurrence include the sphenoid wing, olfactory groove, and frontal lobe.

Meningiomas are the most common type of non-malignant tumors found in the brain. Meningiomas are often insidious in progression, leading to subtle progressive changes that may go unnoticed as the condition progresses. They may initially herniate into the subarachnoid space and dural sinuses leading to intracranial hypertension. Meningiomas eventually compress on adjacents vessels and sections of the brain, causing an array of symptoms and eventual tissue atrophy.

Tumors of the pituitary gland have also been reported to cause FKS and are the second-highest cause of cerebral tumors. This risk becomes exacerbated in patients who have undergone surgical resection for pituitary adenomas and radiotherapy as they may subsequently develop complications, including tentorial meningiomas.