Bitemporal Hemianopia

History Taking

Chief Complaint:

• Complaints of visual loss, usually peripheral vision

• Difficulty in reading, driving, or navigating spaces

• Bumping into objects

History of Presenting Complaint:

• Noticing gaps or blind spots in the field of vision

• Gradual, insidious onset

• May have associated headaches

• Often, visual disturbances are more pronounced in low light conditions

System Review:

• Headache, particularly if persistent or worsening

• Symptoms suggestive of pituitary dysfunction such as weight gain, lethargy, menstrual irregularities (due to pituitary adenoma)

• Acromegalic features such as enlarged hands, feet, facial changes (due to growth hormone-secreting pituitary adenoma)

• Symptoms of hyperthyroidism such as weight loss, palpitations, heat intolerance (due to TSH-secreting pituitary adenoma)

• Symptoms of adrenal insufficiency like fatigue, weight loss, hypotension, salt craving (secondary to ACTH deficiency)

• Galactorrhea, decreased libido, infertility (due to prolactin-secreting pituitary adenoma)

Past Medical History:

• History of other visual disturbances or eye disease

• History of endocrine disorders

• History of neurological disorders or neurosurgical interventions

• History of cranial radiation therapy

Past Surgical History:

• History of brain or pituitary surgery

• History of any radiation treatment

Drug History:

• Use of medications such as corticosteroids which can affect the pituitary gland

• Medications for existing endocrine disorders

Family History:

• Family history of pituitary tumors or other endocrine disorders

• Family history of visual disturbances or eye diseases

Personal History:

• Any history of trauma or injury to the head or eyes

• Exposure to radiation or toxic substances

Social History:

• Impact of visual symptoms on daily activities, work, or driving

• Support system available, especially if visual loss is significant

Physical Examination

General Examination:

• Observe for acromegalic features (large hands and feet, coarse facial features, prominent jaw) indicative of a growth hormone-secreting pituitary adenoma

• Look for signs of Cushing's syndrome such as central obesity, 'moon face', and 'buffalo hump', indicative of ACTH-secreting pituitary adenoma

• Notice any signs of hypogonadism such as reduced body hair or gynecomastia in males, amenorrhea in females (due to pituitary adenoma)

Face (Eyes, Nose, Mouth):

• Bitemporal hemianopia observed during visual field testing

• Optic atrophy or papilledema on fundoscopy

Neurological Examination:

• Assessment of visual acuity might show reduction

• Assessment of visual fields will show loss of vision in the outer (temporal) half of both eyes

• Cranial nerve examination is important, specifically cranial nerve II (optic nerve) for visual acuity, visual fields, color vision, and fundoscopy; and cranial nerve III (oculomotor nerve) for pupillary reactions and eye movements

• Other cranial nerves may be affected, especially in larger lesions or with mass effect, so a full cranial nerve examination should be undertaken

Additional Examination if Required:

• Endocrine assessment may be necessary if symptoms suggestive of hormonal hyper- or hyposecretion are present. This could include tests of thyroid, adrenal, and gonadal function

Investigations

Laboratory Tests:

• Complete blood count: Can show anemia or other hematological abnormalities associated with some pituitary disorders

• Serum prolactin: Elevated in prolactinomas

• Serum growth hormone and insulin-like growth factor-1: Elevated in acromegaly

• Serum TSH and free thyroxine: Assess thyroid function, could be abnormal in a TSH-secreting pituitary adenoma

• Serum ACTH and cortisol: Assess adrenal function, could be abnormal in a ACTH-secreting pituitary adenoma

• Serum FSH, LH, testosterone/estradiol: Assess gonadal function, could be abnormal in gonadotroph-secreting pituitary adenoma

Imaging Studies:

• Magnetic Resonance Imaging (MRI) of the brain with contrast: Gold standard for visualizing pituitary tumors or other structural lesions causing the bitemporal hemianopia

• Computed Tomography (CT) scan of the brain: If MRI is contraindicated or not available, a CT can provide some information, though it is less sensitive than MRI for detecting pituitary tumors

Invasive Tests:

• Visual field testing (perimetry): Though technically non-invasive, this is a specific test to map the visual field loss in detail

• Lumbar puncture: If there is concern about intracranial hypertension as a cause of papilledema

Other Tests:

• Dynamic pituitary function tests: These can include tests like the dexamethasone suppression test or growth hormone suppression test, depending on the suspected pituitary disorder

Management

General Management:

• Patient education about the nature of the disease and treatment options

• Regular follow-ups for monitoring disease progression and treatment response

Medical Management:

• Dopamine agonists like cabergoline or bromocriptine for prolactin-secreting adenomas

• Somatostatin analogs (like octreotide) or growth hormone receptor antagonists (like pegvisomant) for growth hormone-secreting adenomas

• Steroid replacement for ACTH deficiency, levothyroxine for TSH deficiency, sex hormone replacement for gonadotropin deficiency

• For hormone secreting adenomas, medications to block the effects of excess hormones may be used (such as antithyroid drugs for a TSH-secreting adenoma)

Surgical Management:

• Transsphenoidal surgery to remove the pituitary tumor is often the first-line treatment for larger or symptomatic tumors, especially if causing significant visual impairment

• Craniotomy may be required for larger tumors or if transsphenoidal approach is not feasible

• Radiotherapy (either conventional or stereotactic) may be used as adjunctive therapy after surgery, especially in tumors not completely removed or for non-resectable tumors

Other Management:

• For visual symptoms, referral to an ophthalmologist for further management and regular visual field testing to monitor disease progression

• For pituitary apoplexy (a rare but serious complication), urgent neurosurgical referral is required

• Regular endocrinology follow-up for patients with residual pituitary function or requiring ongoing medical treatment for pituitary tumors

• Psychosocial support and counselling as needed, given the chronic nature of the disease and potential impact on quality of life

• Consideration of genetic counselling and screening for familial conditions in patients with certain types of pituitary tumors.