A 43-year-old woman comes to the physician because of weakness and pain in her left hand for the past 3 weeks. She has no other complaints. Her other medical problems include left-sided breast cancer for which she underwent lumpectomy and radiation therapy 1 year ago.
Examination shows no edema of the left arm, but pain to palpation of the medial forearm and hand. She also has weakness throughout the muscles of her left hand (4/5) compared to the muscles of her right hand. Both pupils are reactive (left eye: 3 mm, right eye: 4 mm), but there is mild ptosis on the left.
Which of the following is the most likely diagnosis?

Question

A 43-year-old woman comes to the physician because of weakness and pain in her left hand for the past 3 weeks.  She has no other complaints.  Her other medical problems include left-sided breast cancer for which she underwent lumpectomy and radiation therapy 1 year ago.
Examination shows no edema of the left arm, but pain to palpation of the medial forearm and hand.  She also has weakness throughout the muscles of her left hand (4/5) compared to the muscles of her right hand.  Both pupils are reactive (left eye: 3 mm, right eye: 4 mm), but there is mild ptosis on the left.
Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec193a_9879_0ca3_853d_df44b6c48c6f_MD0002_00 This patient's presentation is consistent with brachial plexopathy, which is most commonly associated with breast and apical lung cancer. Brachial plexopathy can occur from direct cancer invasion or from radiation injury. Patients typically develop gradual weakness in the brachial plexus distribution; the above table summarizes the differences between cancer-induced and radiation-induced brachial plexopathy. Direct cancer invasion of the plexus nerves usually presents with more severe pain at symptom onset, involves the lower plexus, and is associated with Horner syndrome.Radiation injury presents with pain later in the symptom course, affects the upper plexus, and has more paresthesias and weakness. Direct cancer invasion of the plexus nerves usually presents with more severe pain at symptom onset, involves the lower plexus, and is associated with Horner syndrome. Direct cancer invasion of the plexus nerves usually presents with more severe pain at symptom onset, involves the lower plexus, and is associated with Horner syndrome. Radiation injury presents with pain later in the symptom course, affects the upper plexus, and has more paresthesias and weakness. Radiation injury presents with pain later in the symptom course, affects the upper plexus, and has more paresthesias and weakness. Electromyography can also help distinguish between the 2 conditions (i.e., fasciculations and myokymia are more likely to be seen in radiation plexitis). This patient's lower plexus pain and Horner syndrome suggests cancer-induced rather than radiation-induced plexopathy (Choice A). (Choice C) Carpal tunnel syndrome can present with hand weakness and pain but only involves those muscles related to the median nerve. In addition, it is not associated with Horner syndrome as seen in this patient. (Choice D) Cervical spinal cord compression can present with hand weakness, neck pain, spasticity, and possibly loss of proprioceptive sensation in the legs. This patient's localized symptoms in the left hand and ocular findings make this unlikely. (Choice E) Complex regional pain syndrome usually occurs after an injury and presents with throbbing pain, skin temperature changes, and paresthesias in >1 nerve root distribution. This patient's ocular findings and lack of temperature changes makes this less likely. Educational objective: Brachial plexopathy can occur in patients with a history of cancer and radiation therapy. Cancer-induced brachial plexopathy usually presents with more severe pain at symptom onset, involves the lower plexus, and is associated with Horner syndrome. __________ References: Diagnosis and management of brachial plexus lesions in cancer patients. (http://www.ncbi.nlm.nih.gov/pubmed/7577375) Symptomatic brachial plexopathy following treatment for breast cancer: utility of MR imaging with surface-coil techniques. (http://www.ncbi.nlm.nih.gov/pubmed/10715054)

A 43-Year-Old Woman Comes to the Physician Because of Weakness