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Marshall Craig, MD
You are evaluating a patient with upper extremity complex regional pain syndrome (CRPS). She has had only partial relief with stellate ganglion blockade and you explain that part of the sympathetic nerves that innervate her arm may be contributed by Kuntz nerves. The Kuntz nerves are a contribution from:
A) C4 sympathetic fibers to the upper extremity
B) C5 sympathetic fibers to the upper extremity
C) T1 sympathetic fibers to the upper extremity
D) T2 sympathetic fibers to the upper extremity
E) C7 sympathetic fibers to the upper extremity
D) T2 sympathetic fibers to the upper extremity
Correct: (D) T2 sympathetic fibers to the upper extremity. Explanation: The sympathetic supply to the upper extremity is through the grey rami communicantes of C7, C8, and T1 with occasional contributions from C5 and C6. This innervation is through the stellate ganglion. By blocking the stellate ganglion, an effective sympathetic denervation of the upper extremity can be produced. In some cases the upper extremity symphathetic nervous system maybe supplied by the T2 and T3 grey rami communicantes which do not pass through the stellate ganglion. These are Kuntz fibers and have been implicated in inadequate relief of sympathetically maintained pain despite a technically accurate stellate ganglion block.
L. RAMSAROOP, P. PARTAB, B. SINGH, and K. S. SATYAPALThoracic origin of a sympathetic supply to the upper limb: the 'nerve of Kuntz' revisited, J Anat. 2001 Dec; 199(Pt 6): 675-682 2) Cho HM, Lee DY, Sung SW. Anatomical variations of rami communicantes in the upper thoracic sympathetic trunk. Eur J Cardiothorac Surg. 2005 Feb;27(2):3204.
A 48 year old man with depression and a history of benign prostatic hypertrophy (BPH) has been taking gabapentin for neuropathic pain, but states that it is making him depressed. You consider starting a medication for neuropathic pain that also has antidepressant effects. Which of the following is a tricyclic antidepressant (TCA) that would be most appropriate in a patient with BPH?
Correct: (D). Desipramine. Explanation: TCAs are substances that contain a fused three ring moiety and are used in the treatment of depression as well as chronic pain. These drugs block the uptake of norepinephrine and serotonin into axon terminals and may block some subtypes of serotonin, adrenergic, and histamine receptors. TCAs have been shown to relieve central poststroke pain, postherpetic neuralgia, painful diabetic and non-diabetic polyneuropathy and postmastectomy pain syndrome, but not pain from spinal cord injury, phantom limb pain, or HIV neuropathy pain. They are considered one of the first line treatments for neuropathic pain with a number needed to treat of only 2. Desipramine is a secondary amine TCA and is therefore less likely to exhibit anticholinergic side effects. Nortriptyline is another TCA in this class. (AC) are tertiary amine TCA's, more likely to exhibit anticholinergic side effects including urinary retention, dry mouth, confusion, hypotension and hallucinations. Care should be exercised in starting TCAs in patients with glaucoma or cardiac disease. The anticholinergic effects may exacerbate glaucoma and promote cardiac dysrhythmias (commonly sinus tachycardia or intraventricular conduction delay with QRS prolongation or prolongation of PR and QT intervals can occur). There is a narrow therapeutic window for TCA's, as the therapeutic dose is very close to the toxic dose. (D) is a selective serotonin reuptake inhibitor (SSRI). While SSRIs can be of benefit in chronic pain by treating patients with depression and thereby altering the perception of the severity of pain, they have not been found to have analgesic activities independent of their antidepressant effects. Serotonin norepinephrine reuptake inhibitors (SNRIs) and TCA's are the antidepressants primarily used to treat pain independent of depression. However, caution must be used in starting both of these classes of drugs due to the side effect profiles.
Uher, R., Farmer, A., Henigsberg, N., Rietschel, M., Mors, O., Maier, W., ... & Aitchison, K. J. (2009). Adverse reactions to antidepressants. The British Journal of Psychiatry, 195(3), 202210. Tricyclic antidepressant (English). Medical Subject Headings. U.S. National Library of Medicine. Finnerup NB1, Otto M, McQuay HJ, Jensen TS, Sindrup SH. Algorithm for neuropathic pain treatment: an evidence based proposal. Pain. 2005 Dec 5;118(3):289305. Epub 2005 Oct 6.
Questions taken from the Pain Medicine ABA/ABPM Exam Question Bank.