4. Samborski CS, Mix JA. Foreign body in tongue. Oral Surg Oral MedOral Pathol. 1985;59:549.

5. Sharma PK, Songra AK, Ng SY. Intraoperative ultrasound-guidedretrieval of an airgun pellet from the tongue: a case report. Br J OralMaxillofac Surg. 2002;40:153-155.

Femoral Nerve Block for Femur Fractures

To the Editor:We undertook a pilot study evaluating femoral nerve block

for the management of pain for patients with traumatic mid anddistal femur fractures during the emergency department (ED)phase of care.

Alert, adult patients with isolated, closed, mid and distalfemoral shaft fractures were consented and randomized toreceive either a femoral nerve block and morphine or morphineonly immediately after identification of the injury. The hospitalinstitutional review board approved this study. Previous treat-ment with analgesics did not preclude participation. Thefemoral nerve block was administered by resident or attendingemergency physicians trained in its use. Training consisted oflecture and online components (total time required: 90minutes). The femoral nerve block was carried out bypercutaneous needle infiltration of 20 mL of bupivacaine 0.5%in the area of the femoral nerve as it traversed the femoral canal,immediately lateral to the femoral arterial pulsation. Therewas no application of distal pressure as done with the‘‘3-in-1 block.’’1 Adjuncts such as nerve stimulators or ultra-sonographic guidance were not used. One hundred-millimetervisual analog scale measurements were obtained immediatelyafter randomization. Patients randomized to the morphine-onlylimb received 0.1 mg/kg of morphine intravenously immedi-ately after visual analog scale determination. Patients random-ized to femoral nerve block received this interventionimmediately after visual analog scale determination. Studyinterventions were performed by persons not directly caring forthe patient. The physician(s) and nurse(s) caring for the patientwere blinded to treatment limb. All patients, upon theirrequest, were administered subsequent doses of morphine. Thedose and frequency were determined by the primary physician.Fractures were managed in a standardized fashion includingtraction splinting and orthopedic consultation. Comparison wasmade between groups of initial visual analog scale, visual analogscale reduction at 1 hour, and the administration of rescue dosesof morphine.

We enrolled 16 patients. Ten were randomized to receivefemoral nerve block and 6 to receive morphine only. The initialvisual analog scale scores were not different (P=.83). Themedian visual analog scale reduction at 1 hour for the femoralnerve block group and morphine-only group were 56 mm (SD24) and 11 mm (SD 14), respectively (P\.05). Rescuemorphine was requested by 1 of the 10 patients randomized tofemoral nerve block compared with 5 of the 6 patients in themorphine-only group (relative risk 8.3, 95% confidence interval1.2 to 55). No patients encountered cardiovascular, centralnervous system, or gastrointestinal adverse effects.

These results suggest that femoral nerve block may besuperior to systemic opioid administration in providing anal-gesia in femoral shaft fractures. Further investigation of regionalanesthesia for management of acute pain in the emergencyphase of care is warranted.

Wayne Triner, DO, MPHJames Levine, MDShin-Yi Lai, MDMara McErlean, MDDepartment of Emergency MedicineAlbany Medical CollegeAlbany, NY

doi:10.1016/j.annemergmed.2004.12.031

Presented at the Society of Academic Emergency MedicineScientific Assembly, Boston, MA, May 2003.

1. Fletcher AK, Rigby AS, Heyes FL. Three-in-one femoral nerve block asanalgesia for fractured neck of femur in the emergency department:a randomized, controlled trial. Ann Emerg Med. 2003;41:227-233.

Correspondence

Volume 45, no. 6 : June 2005

Response to Latrodectus-Associated CompartmentSyndrome

To the Editor:We were somewhat perplexed by the recent case report from

Cohen and Bush1 regarding compartment syndrome after asuspected black widow spider bite. As pointed out in the report,significant compartment pressure elevations have never beenreported after documented Latrodectus envenomation. For severalreasons, we are concerned that the pressure elevations reported inthis case were attributed to a bite by a Latrodectus spider.

Many of the patient’s physical findings on presentation areinconsistent with typically reported Latrodectism. Latrodectusbites are almost always immediately painful, like a pin-prick,with mild local skin changes frequently noted (small puncturewound, ‘‘target lesion,’’ or local diaphoresis). Severe extremityenvenomations begin with local cramping pain virtually alwaysprogressing to generalized back, abdomen, and chest pain.2 Inthe present case, symptoms were delayed, and the skin surfaceover the affected extremity was described as normal. In contrast,‘‘marked swelling’’ was eventually described of his forearm. Theseverity of eventual ‘‘deep’’ local reaction is inconsistent with hislack of chest, abdomen, or back pain and cramping.

Few spider species possess fangs long and strong enough topierce human skin. Those that do, such as Latrodectus, posemedical risks. However, unlike snake fangs that occasionallypenetrate deeper tissue structures, female black widow fangs areapproximately 0.5 mm (G0.1 mm) in length (Rick Vetter, MS,personal communication, November 2004), which is toosmall to penetrate the muscle compartment, allowing only forintradermal or subdermal injection of venom. Similar to thepathophysiology occurring after most superficial snakebites,

Annals of Emergency Medicine 679

In reply:We thank Matteucci et al for their interest in our case report,

and we appreciate the opportunity to respond to their letter. Wedisagree with their assertion that ‘‘Latrodectus bites are almostalways immediately painful.’’ Other authors attest that ‘‘manybites are not recognized initially’’1 and ‘‘often the victim doesnot notice he has been bitten.’’2 These observations arecorroborated by other literature, as well as by our own clinicalexperience treating many patients with black widow spider bites.Similarly, local skin changes may be noted but often are not.For example, in Clark et al,3 a ‘‘target lesion’’ was noted in lessthan half the patients. In a series from our own institution, therewas no discernable envenomation site found in more than onethird of patients with black widow spider bites.4 In anotherseries, only 6% manifested puncture marks, and only 34% hadlocal or regional diaphoresis.5 Local findings after black widowspider bites are often very subtle.

The authors of this correspondence are mistaken in theircontention that symptoms in our case were delayed (45minutes). In fact, the average time from envenomation untilonset of symptoms was over an hour and up to 12 hours in oneseries3 and up to 6 hours in another.5

It is likely that widow spider fangs are too small to penetratemuscle compartments. However, the effects of widow spidervenom are often observed to affect local musculature as well asmuscles remote from the bite site. Local or extremity painaround the site of the bite was noted in 38% of patients in 2series.3,5 Therefore, we were not surprised that the muscles ofour patient’s arm were severely affected. However, we neverattributed the compartment syndrome to local ‘‘cytotoxic’’venom activity. Instead, we hypothesized that repeated,sustained muscle contractions induced by widow spiderenvenomation led to this patient’s injuries. Similarly, com-partment syndrome has been reported after strenuous exercise,such as weight lifting. This form of trauma could have causedthe hemorrhage observed on ultrasonography as well. We neverimplied or suggested that widow spider envenomation leads tocoagulopathy.

We disclosed all therapeutics given to the patient. Hisextremity was not elevated, and ice was not applied. We couldnot find any evidence in the literature to support that morphinereduced compartment pressures, although we are aware of manycases where it did not prevent fasciotomy. In contrast, thispatient’s compartment pressures decreased from a surgical to anonsurgical range after black widow spider antivenom. We think

Correspondence

Latrodectus venom should be distributed in the subcutaneousor dermal tissue and eventually absorbed systemically eitherthrough the lymphatics or cutaneous blood vessels. Diffusionthrough the fascia into the compartment should be minimal.

Finally, alpha-latrotoxin, the most important componentin black widow venom, is minimally cytotoxic. Instead, as apotent neurotoxin, it acts at nerve terminals by forming cationpores in the cell membrane. This allows calcium influx, resultingin depolarization of nerve cells and release of neurotransmitters,leading to muscular contraction and the symptoms seen inLatrodectism.3 Even if some localized underlying muscle con-traction would have occurred in this case, it is most oftenintermittent2 and should not lead to compartment syndrome. Inaddition, since alpha-latrotoxin has not been associated withcoagulopathy or bleeding, the presence of the intracompartmentalhematoma found on magnetic resonance imaging is unexplained.

Latrodectus antivenom can be highly effective and functions bybinding and neutralizing alpha-latrotoxin. As was done in thiscase, patients presenting with suspected or documentedLatrodectus bite and severe symptoms should be consideredfor antivenom. Unfortunately, the reader is not informed inthis case about other therapies besides morphine that mayhave occurred either before or simultaneously with the admin-istration of antivenom that may have contributed to this patient’simprovement. Elevation of the extremity, ice, and administrationof vasoactive agents such asmorphine can influence compartmentpressures independently in some cases.4

Although the sighting of a black spider and the patient’sclinical improvement temporally related to the administration ofLatrodectus antivenom in this case support the possibility ofLatrodectus-induced compartment pressure elevations, the readershould carefully consider pharmacologic and pathophysiologicmechanisms before adding alpha-latrotoxin to the list of etiologiesfor compartment syndrome. The presence of an intracompart-mental hematoma on magnetic resonance imaging suggests adifferent mechanism of injury, such as unreported trauma.

Michael J. Matteucci, MDSaralyn R. Williams, MDRichard F. Clark, MDDivision of Medical Toxicology, University of California SanDiego Medical Center, San Diego, CA

doi:10.1016/j.annemergmed.2004.12.033

This correspondence was co-written by LCDR Michael J.Matteucci, MC, USNR while a fellow at UCSD Medical Centertraining in Medical Toxicology. The views expressed in thecorrespondence are those of the authors and do not reflect theofficial policy or position of the Department of the Navy,Department of Defense, nor the U.S. Government.

1. Cohen J, Bush S. Case report: compartment syndrome after asuspected black widow spider bite. Ann Emerg Med. 10.1016/j.annemergmed.2004.06.018.

680 Annals of Emergency Medicine

2. Clark RF, Wethern-Kestner S, Vance MV, et al. Clinical presentationand treatment of black widow spider envenomation: a review of 163cases. Ann Emerg Med. 1992;21:782-787.

3. Ushakaryov YA, Volynski KE, Ashton AC. The multiple actions of blackwidow spider toxins and their selective use in neurosecretionstudies. Toxicon. 2004;43:527-542.

4. Robinson D, On E, Halperin N. Anterior compartment syndrome of thethigh in athletesdindications for conservative treatment. J Trauma.1992;32:183-186.

Volume 45, no. 6 : June 2005