Sensory Case Study 3

Visual Disorder

A 55 year old woman with hypertension and hypothyroidism was admitted to the Neurology Service at the Methodist Hospital for urgent evaluation of visual loss, diplopia and weakness of the lower extremities. Two weeks ago, she noted the painless onset of blurred vision in the right eye, which has not significantly progressed. Five days ago, she developed double vision, which has worsened. She cannot attribute any change in diplopia to a particular direction of gaze, but reports that the two visual images are typically side-by-side (i.e. horizontal diplopia) in all positions. She denies associated eye pain or discomfort, headache, dysarthria, dysphagia, or confusion. She has never experienced such symptoms in the past.

 

Later on the same day that her double vision began, she experienced bilateral lower extremity weakness, with progressive gait difficulty over the past 5 days. She also reports poorly localized numbness in both hands and throughout her legs. On direct questioning, she believes that her gait imbalance is out of proportion to her symptoms of weakness.

 

On the day of admission, the patient was examined by an ophthalmologist, who suspected an acutely evolving disorder of the nervous system, and referred her for urgent evaluation.

 

Past Medical History:

1. Traumatic head injury in 1992 from a weather balloon accident, without loss of consciousness. At this time the patient suffered a left orbital injury associated with mildly decreased visual acuity and an irregular fixed pupil in the left eye, which has not changed.

2. Hypertension, long-standing

3. Hypothyroidism

4. Depression

5. Asthma

6. The patient has been hospitalized four times in the past year for nausea and vomiting. According to the patient, her medical evaluations were unremarkable, and she was given a presumptive diagnosis of gastritis. Her nausea has decreased, but her appetite is poor, and she has lost 20 pounds in the past two months.

7. Hysterectomy 20 years ago for endometriosis; no blood transfusions.

 

GENERAL QUESTIONS:

1. Why is there electrical activity in the brain? Describe how nerve impulses are transmitted from neuron to neuron.

2. What is myelin? What is its function?  Explain.

3.Compare and contrast the structure and functions of the Central Nervous System and the Peripheral Nervous System.

SPECIFIC QUESTIONS:

1.)   Explain the mechanism of phototransduction in the eye.  Be sure to include anatomy and cellular structures within the retina.

2.)   Why do humans have circular pupils?

3.)   What is diplopia?  dysarthria? dysphagia?

4.)   Could the diplopia and ataxia be related?  Explain.

5.)   Could these neurological problems be related to her head injury suffered in 1992?  Why would the symptoms appear at this time?

6.)   Could these neurological symptoms be related to the womanÕs anything else in the womanÕs past medical history? Explain.

7.)   What course of treatment(s) would you suggest?