Answers and Explanations

Answer A, A lesion to die medial medulla may affect the medial lemniscus and corticospinal tract. The key localizing sign is tongue deviation to the left upon protrusion, implicating the left hypoglossal nerve, which exits from the medial medulla. 2. Answer E. The nucleus of Edinger Westphal is found in the rostral midbrain. The only other midbrain structure that would be found in the same section is the superior colliculus. 3. Answer C. The lesion involves the corticospinal tract resulting in...

Pontocerebellar Angle Syndrome

Pontocerebellar angle syndrome is usually caused by an acoustic neuroma (schwannoma) of CN VIII. This is a slow-growing tumor, which originates from Schwann cells in the vestibular nerve (or less commonly the auditory nerve). As the tumor grows, it exerts pressure on the lateral part of the caudal pons where CN VII emerges and may expand anteriorly to compress the fifth nerve. The cranial nerve deficits seen together localize the lesion to the brain stem, but the absence of long tract signs...

Review Questions

A middle-aged patient develops persistent headaches that are resistant to over-the-counter analgesics. Imaging reveals that the patient has a noncommunicating hydrocephalus. Which of the following is the most likely cause of this condition (B) Meningitis affecting the arachnoid granulations (C) A thrombosis in the cavernous sinus 2. Hydrocephalus has resulted in a patient in enlargement of one lateral ventricle. Which of the following is the most likely site of a blockage (D) Superior sagittal...

Lateral Pontine Syndrome

Lesions Trigeminal Nerve

Lesions of the dorsolateral pons usually result from occlusion of the anterior inferior cerebellar artery (caudal pons) or superior cerebellar artery (rostral pons). The long tracts involved will be the same as in lateral medullary syndrome, the spinothalamic tract and the descending hypothalamic fibers. The cranial nerves involved will be the facial and vestibulocochlear in the caudal pons, the trigeminal nerve in the rostral pons, and the spinal nucleus and tract of V in both lesions (Figure...

Lateral Medullary Wallenberg Syndrome

Lateral medullary syndrome results from occlusion of the PICA (Figure IV-5-15). The cranial nerves or nuclei involved in the lesion are the vestibular or the cochlear parts of CN VIII, the glossopharyngeal and the vagus nerves, and die spinal nucleus or tract of V. The long tracts involved are the spinothalamic tract and the descending hypothalamic fibers. Spinothalamic tract lesions produce a pain and temperature sensation deficit in the contralateral limbs and body. Lesions of descending...