Sensory Case Answers Case 1 This patient has breast cancer with a brain metastasis in the right parietal lobe. The metastasis is irritating the surrounding cortical tissue and triggering focal seizures (simple partial seizures with sensory symptomatology – you will learn more about this next semester). The pattern in which the tingling sensation spreads makes sense when you think of the anatomic layout of the homunculus – symptoms flow from one adjacent area to the next – know as a “Jacksonian march”. There is no deficits in primary sensory modalities on exam, but there are cortical (parietal) sensory findings, including astereognosis, agraphesthesia, and extinction on double simultaneous stimulation. Deficits are on the left side, indicating a right sided lesion. Case 2 This patient has multiple sclerosis, with a large plaque in the dorsal (posterior) columns at the C3 level. The patient has no abnormalities in pain and temperature perception, indicating the spinothalamic tract is not involved. The patient does have impairment of vibratory sense and proprioception. The presence of symptoms in all extremities sparing the face helps localize the lesion. CN V, which supplies sensation to the face, comes off the pons. Involvement of the upper extremities indicates the lesion is above a C 5 level - so the lesion has to be between C4 and the pons. This means the lesion is either in the dorsal columns at a high cervical level or is in the medial lemniscus bilaterally below the level of CN V in the pons. The patient has difficulty with fine hand movements and drops things because of impaired proprioception (she cannot feel her exact hand position). Her problem is not due to weakness. The “squeezing” feeling that she describes in her extremities is described in patients with dorsal column lesions. Case 3 This patient has a thalamic hemorrhage due to hypertension. The marked involvement of primary sensation for all modalities helps localize the lesion to the thalamus. Because sensory symptoms are on the right side of the body, the lesion is on the left. Because the face is involved, you know the lesion has to be at, or above, the level of the pons. The subsequent appearance of chronic unprovoked pain on the same side as the sensory deficit (“thalamic pain syndrome”) helps localize the lesion to the thalamus. The exact etiology of this pain syndrome is not well understood. Case 4 This patient has a disc herniation at L4-5 on the left, with left L5 radiculopathy. If you look at a diagram of the dermatomes, you will see that the distribution of this patient’s pain and deficit in pinprick fits the distribution of the L5 dermatome. This distribution is similar to the distribution of the sensory branch of the peroneal nerve. The onset associated with acute low back pain favors radiculopathy. The patient has increased pain and tingling with cough or straining to move his bowels because anything triggering a Valsalva maneuver causes a transient increase in intracranial pressure. Case 5 This patient has tumor compressing the left side of his spinal cord at the C6 level. Involvement of the dorsal (posterior) column on the left causes a loss of vibratory sense and proprioception below the level of the lesion on the same side of the body, because these pathways ascend uncrossed until the level of the medulla. Involvement of the spinothalamic tract results in loss of pain and temperature sense below the level of the lesion on the opposite side of the body, because pain and temperature fibers cross over to the opposite side of the cord within two levels up. The C6 nerve root is compromised on the left, causing pain in a left C6 dermatomal distribution.

From: Atlas of Human Anatomy, Netter