midbrain syndromes

Idara Eshiet C.

Midbrain syndromes

Case 1

• A 45 year old woman who had abdominal surgery 2 weeks before suddenly remarked to her husband that she was seeing double. She also felt a weakness in her right arm and leg. Her husband noticed that her left eyelid was drooping.

• At the hospital she was awake, well oriented with normal memory. Her general physical condition was good. Her speech was articulate and the content was good. Her visual fields were normal but when asked to open her eyes the left eyelid did not open fully. When asked to look straight ahead the left eye was deviated to the left. On attempted lateral gaze to the right, only the right eye responded. When asked to converge the eyes only the right eye was adducted and only the right eye showed pupillary constriction. Only the right eye constricted in response to light.

• Upon smiling there was a minor weakness on the right. Her palate elevated symmetrically, gag reflex was normal, and corneal and jaw jerk responses were normal. The tongue protruded midline.

• Motor strength was normal in the extremities on the left but was reduced on the right, especially in the arm where there was an increased biceps reflex and resistance to passive stretch.

• Sensory examination was normal for the face and body on both sides.

Case 2

•  A usually alert 80 year old man was observed to have an episode of loss of consciousness. Upon awakening he complained of double vision and there was a notable tremor in his left arm.

• The general physical exam was normal for a man his age. There was a mildly elevated blood pressure. Mental status was good and speech was articulate and appropriate.

• With the eyelids retracted the right eye had a dilated pupil and a lateral strabismus. On attempted lateral gaze to the left the right eye would not proceed across the midline. Although vision was normal the right pupil did not constrict in either the direct or consensual pupillary light reflexes. Hearing was normal as were cranial nerves 5 through 12. Pain and temperature sensation from the face and body was normal bilaterally. Proprioception and vibratory sense on the right side of the body was normal but was diminished on the left.

• Muscle strength on the left was slightly diminished and deep tendon reflexes were slightly increased. There was no Babinski sign. The finger-to-nose test was normal on the right but the left arm showed an intention tremor and dysmetria. There were occasional involuntary movements of the left arm.

Case3

A 39 year old man awoke with a horizontal diplopia especially on right gaze. 5 days later, a Hess chart examination performed by an ophthalmologist showed paresis of the lateral rectus muscle. On admission 19 days after onset, the patient showed a mild paresis of the right abducens nerve and a subtle weakness of his left leg with moderate hyperreflexia in the left upper and lower limbs.

Babinski’s reflex was positive and abdominal reflex was absent on the left side , no facial weakness or deviation of the tongue on protrusion was found. All other general and neurological exams were normal.