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RIGINAL ARTICLE

lnar Neuropathy at or Distal to the Wrist: Traumatic Versusumulative Stress Cases

nthony Chiodo, MD, Edmund Chadd, MD

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ABSTRACT. Chiodo A, Chadd E. Ulnar neuropathy at oristal to the wrist: traumatic versus cumulative stress cases.rch Phys Med Rehabil 2007;88:504-12.Objective: To identify clinical and electromyographic char-

cteristics of ulnar neuropathy at or below the wrist, comparinghose caused by unitary trauma with those caused by suspectedumulative stress.

Design: Retrospective case series.Setting: University hospital electromyography laboratory.Participants: Patients with electrodiagnostic evidence of an

lnar neuropathy at or distal to the wrist over a 3-year period.orty-seven hands from 42 patients (age range, 20�80y; mean,2y) were identified and evaluated in this study.Interventions: Record review of clinical history, physical

xamination, electromyography, and treatment.Main Outcome Measures: Etiology of injury, physical

igns and symptoms, and electromyographic testing results.Results: Ulnar neuropathy at or distal to the wrist is commonly

ischaracterized because of other mononeuropathies in the upperxtremity and because of peripheral polyneuropathy. Ulnar neuropa-hy because of cumulative stress presents typically with sensoryymptoms (63%) and a normal examination (71%), whereas traumaases present with motor with or without sensory symptoms (92%)ith motor abnormalities (92%) confirmed on examination. Trau-atic cases are characterized by electromyography by decreased

ensory and motor-evoked amplitudes, prolonged motor distal laten-ies, and abnormal needle examination. The amplitude changes areoted comparing with laboratory norms and comparing side to side.o characteristic pattern of abnormalities on electromyography isoted in the cumulative stress cases. Patients with no motor symp-oms, regardless of etiology, are more apt to have sensory distalatency prolongation, whereas those with motor symptoms have mo-or amplitude and needle examination abnormalities.

Conclusions: Traumatic ulnar neuropathy at or distal to therist is characterized by motor symptoms and sensory andotor axonal loss by electromyography, whereas cumulative

tress cases have sensory symptoms and electromyographicndings that are highly variable and noncharacteristic. Patientsith no motor symptoms are more apt to show sensory distal

atency abnormalities on electromyography, whereas thoseith motor symptoms show motor-evoked amplitude and nee-le electromyography abnormalities.Key Words: Electromyography; Rehabilitation; Ulnar neu-

opathies; Wrist.© 2007 by the American Congress of Rehabilitation Medi-

ine and the American Academy of Physical Medicine andehabilitation

From the Department of Physical Medicine and Rehabilitation, University ofichigan Hospital, Ann Arbor, MI.No commercial party having a direct financial interest in the results of the research

upporting this article has or will confer a benefit upon the author(s) or upon anyrganization with which the author(s) is/are associated.Reprint requests to Anthony Chiodo, MD, Dept of Physical Medicine and Reha-

ilitation, University of Michigan Hospital, 325 E Eisenhower Pkwy, Ann Arbor, MI8108, e-mail: [email protected].

a0003-9993/07/8804-11157$32.00/0doi:10.1016/j.apmr.2007.01.002

rch Phys Med Rehabil Vol 88, April 2007

LNAR NEUROPATHY AT OR DISTAL to the wrist is arare, but well-described, condition.1-10 An understanding

f ulnar nerve anatomy as it passes into the hand throughuyon’s canal at the wrist has led to a well-defined schema ofpatterns of ulnar neuropathy depending on the site of the

esion.2 A type I lesion occurs either outside or just within theroximal end of Guyon’s canal and affects the mixed ulnarerve. All of the hand intrinsic muscles and sensation of theedial 1.5 digits are affected, but the dorsal ulnar cutaneous

ensory branch distribution is spared. A type II lesion is locatedithin Guyon’s canal and affects only the superficial sensoryranch, creating a pure sensory neuropathy of the medial 1.5igits. A type III lesion involves the deep motor branch distalo its bifurcation from the superficial sensory nerve but prox-mal to the motor branch to the hypothenar compartment. Thisesion results in a pure motor neuropathy affecting all the handntrinsics including the hypothenar muscles. A type IV lesionccurs on the deep motor branch distal to the hypothenarranch, preserving hypothenar function but affecting otherlnar-innervated hand intrinsics. A type V lesion occurs justroximal to the branches supplying the first dorsal interosseousFDI) and adductor pollicis muscles, resulting in decreasedctivity of these muscle groups only.

However, in practice, diagnosis of ulnar neuropathy at oristal to the wrist is rarely easy. Complaints of paresthesias areften nonspecific or may be related to coexisting pathologies,ommonly including carpal tunnel syndrome (CTS).5,8,11 Theomplex innervation pattern of the superficial and deepranches makes electrodiagnosis a challenge. Furthermore,everal conditions in the differential diagnosis such as ulnareuropathy at the elbow, C8-T1 radiculopathy, and peripheraleuropathy may result in similar clinical presentations andlectrophysiologic patterns as ulnar neuropathy of the wrist.12

he standard approach to electrodiagnosis of ulnar neuropathyf the wrist involves recording (1) sensory nerve action poten-ials (SNAPs) from the ulnar nerve proximal to the wrist toigit V,4 (2) compound motor action potentials (CMAPs) fromhe wrist to the abductor digiti quinti (ADQ) and FDI,13 (3)orsal ulnar cutaneous branch SNAP,14 and (4) needle electro-yography examination of the ulnar-innervated hand muscles.A review of available case series in which presenting symp-

oms are specified (totaling 109 patients) suggests that, of the 5ypes of ulnar neuropathy of the wrist, pure motor neuropathies arehe most common (�50%), followed by mixed sensory and motor�33%), and most rarely, pure sensory lesions (14%).2,12,15-18

esion etiology was caused by unitary trauma in only 12% ofases; 75% of these cases resulted in either pure motor orixed motor and sensory. Cumulative or occupational traumaas the etiology in 25% of cases, over 95% of which was eitherure motor or mixed neuropathy. In the remaining cases, eti-logy was generally either unknown or because of an anatomicause found on surgical exploration (eg, ganglion cyst, anom-lous muscle). Study design among these 6 reports variesidely. One series included only patients with known anatomic

orrelation to the clinical presentation2; a second included patientsnly with a known history of repetitive or unitary trauma, radio-ogic evidence of a lesion at the wrist, or focal pain at the wrist12;
nd a third series excluded patients with fractures, dislocations,

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505ULNAR NEUROPATHY AT OR DISTAL TO THE WRIST, Chiodo

pen wounds at the wrist, or concurrent median neuropathy at therist.18 Given the apparent involvement of the deep motor branch

n the vast majority of cases as described earlier, various newpproaches to electrodiagnosis have been proposed that specifi-ally target motor fibers between the wrist and the FDI.4-7,12 Theseechniques have shown improved sensitivity and specificity forocalizing ulnar nerve lesions at the wrist in select patient groupss compared with the standard approach described previously.

In our experience, however, the majority of patients withlectrodiagnostic abnormalities of the ulnar nerve do notresent with a classic picture of ulnar neuropathy. The purposef this study was to evaluate standard electrodiagnostic criteriaor ulnar neuropathy of the wrist in a more general patientopulation, with particular focus on the comparison of patientsith cumulative stress compared with patients with ulnar neu-

opathy caused by unitary trauma.

METHODSWe reviewed studies of patients presenting to the Electrodi-

gnostic Laboratory at the University of Michigan over the-year period from January 2002 to January 2005 to identify allatients classified with a diagnostic code for ulnar neuropathyt or distal to the wrist. Nerve-conduction studies were per-ormed by using Nicolet Viking machines.a Sensory studiesere performed with ring electrodes at a distance of 14cm orisk electrodes at a distance of 14cm. Motor studies wereerformed with disk electrodes at a distance of 7cm. Allensory distal latencies were peak latencies. All sensory andotor amplitudes were measured from baseline to peak. Nee-

le examinations were performed with a 22-gauge 37-mmisposable concentric electromyography needle. Surface tem-erature was above 32°C in all cases.Routine sensory nerve conduction studies (NCSs) performed

ncluded the following: (1) median sensory stimulation at therist and recording over digit II, (2) ulnar sensory stimulation

t the wrist and recording over digit V, (3) ulnar dorsal cuta-eous sensory stimulation at the wrist and recording overorsum of the hand, and (4) radial sensory stimulation over theorearm and recording at the wrist.

Routine motor NCSs performed included the following: (1)edian motor stimulation at the wrist and elbow and recording

ver the thenar compartment and (2) ulnar motor stimulation athe wrist, below the elbow, and above the elbow and recordingver the hypothenar compartment and/or FDI muscle.Additional NCSs including lower-extremity studies were per-

ormed on a case-by-case basis depending on clinical presentation.pecific muscle groups were also tested by needle electromyogra-hy including, FDI, ADQ, abductor pollicis brevis, flexor carpilnaris (FCU), or flexor digitorum profundus, root screen, andaraspinal examination.

In each case initially classified as ulnar neuropathy at oristal to the wrist, the electrodiagnostic data were critiqued toonfirm or revise the diagnosis. Patient charts were also re-iewed to obtain a clinical history of systemic disease orrecipitating injury. Alternative diagnoses included ulnar neu-opathy of the elbow, median mononeuropathy at the wristCTS), and peripheral neuropathy. Patients not meeting criteriaor ulnar neuropathy at or distal to the wrist as defined belowere excluded. Additional exclusion criteria were clinical or

lectrodiagnostic evidence of diabetic or other generalizedolyneuropathy and dorsal ulnar cutaneous mononeuropathy.atients with ulnar neuropathy at or distal to the wrist second-ry to penetrating injury or precipitating unitary trauma asudged by clinical history were separated as a group andompared with the patients with history suggestive of a poten-
ial cumulative stress etiology for ulnar neuropathy at or distal n
o the wrist. Surgical reports of ulnar nerve inspection andreatment were obtained when available to correlate electro-yography data with pathologic findings.Electrodiagnostic criteria supporting ulnar neuropathy at or

istal to the wrist included the following: (1) ulnar sensorymplitude across the wrist less than 10�V (�8�V if age �60y)r a side-to-side amplitude difference greater than 50%, (2)lnar sensory distal latency across the wrist greater than 3.5ms�4.1ms if age �60y) or a side-to-side distal latency differ-nce greater than 0.5ms, (3) distal latency difference greaterhan 0.5ms between ulnar sensory at the wrist and a normaledian sensory distal latency at the wrist on the affected side

normative value for median sensory distal latency, �3.7ms),4) ulnar motor amplitude to the ADQ less than 6mV or aide-to-side amplitude difference greater than 50%, (5) ulnarotor distal latency across the wrist greater than 3.5ms

�3.8ms if age �60y) or a side-to-side distal latency differ-nce greater than 1.5ms, (6) normal dorsal ulnar cutaneousCS, and (7) no evidence of a cubital tunnel syndrome or ulnareuropathy at the elbow.Diagnostic criteria of a deep ulnar motor neuropathy in-

luded distal latency to the ulnar motor to the FDI greater thanms longer than the ulnar motor to the ADQ. Diagnosticriteria of cubital tunnel syndrome included motor-evokedmplitude at the below elbow site greater than 20% reducedompared with stimulation at the wrist. Diagnostic criteria oflnar neuropathy at the elbow included the following: (1) ulnarotor amplitude decrease greater than 20% from below elbow

o above elbow and (2) ulnar motor conduction velocity de-rease greater than 20% from the forearm segment to the acrosslbow segment.

Diagnosis of median mononeuropathy at the wrist requires ateast 1 of the following: (1) median sensory amplitude at therist less than 20�V or a side-to-side amplitude differencereater than 50%, (2) median sensory distal latency at therist greater than 3.7ms or a side-to-side distal latencyifference greater than 0.5ms or more than 0.5ms greater thannormal same-side ulnar sensory distal latency, (3) side-to-

ide median motor distal latency difference at the wrist greaterhan 1.5ms or more than 1.5ms greater than a normal same-sidelnar motor distal latency; (3) median versus ulnar midpalmaristal latency difference of greater than 0.4ms at a distance ofcm, and (4) a median versus radial to the thumb distal latencyifference of greater than 0.4ms at a distance of 10cm.

ata AnalysisData analysis compared the unitary trauma and the cumula-

ive stress patients with respect to their clinical presentationith regard to sensory symptoms, motor symptoms, both, or no

ymptoms. The unitary trauma and the cumulative stress pa-ients were compared with regard to their electromyographicresentation. Electrodiagnostic presentation was also comparedetween patients with ulnar-specific sensory symptoms, non-pecific sensory symptoms, motor with or without sensoryymptoms, or no symptoms. Chi-square analysis was used toompare groups in these analyses.

RESULTSOver a 3-year period, 74 electromyography cases were

oded for ulnar neuropathy at or distal to the wrist. On reviewf these reports, 19 cases were noted to have a differentiagnosis than ulnar neuropathy of the wrist based on thestablished criteria in the Methods section (13 cases of ulnareuropathy at the elbow, 4 cases of ulnar dorsal cutaneous
europathy, 1 radiculopathy, 1 midforearm ulnar neuropathy).
Arch Phys Med Rehabil Vol 88, April 2007

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506 ULNAR NEUROPATHY AT OR DISTAL TO THE WRIST, Chiodo

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hese cases were excluded. An additional 10 cases were ex-luded because of evidence of systemic polyneuropathy aseported in the study interpretation (2 diabetic polyneuropathy,

cervical myelopathy, 1 chronic inflammatory demyelinatingolyneuropathy, 1 acute inflammatory demyelinating polyneu-opathy, 1 spastic ataxic disorder patient, 3 unspecified poly-europathy). Three cases with evidence of ulnar conductionlowing across the elbow and wrist were excluded because aouble-crush injury at the wrist and elbow could not be differ-ntiated from a single lesion at the elbow because of incom-lete electromyographic testing. Review of the full patientharts in the remaining 42 cases revealed a history of trauma tohe affected wrist in 12 cases, whereas 30 patients had nossociated unitary traumatic event. These 42 patients yielded7 involved hands.Patient characteristics for the traumatic and cumulative

tress ulnar neuropathy of the wrist patients are summarized inable 1. Presentation with sensory changes as the only symptomas significantly more common in the cumulative stress cases

63%) than the trauma cases (8%) at a P value of less than .05.resentation with no symptoms was seen in the cumulativetress group only. Either motor (42%) or mixed sensory andotor (50%) presentation was statistically more significant in

he trauma group compared with the cumulative stress group.resentation with no physical findings was significantly moreften noted in the cumulative stress group (71% vs 8%),hereas motor physical findings were far more common in the

rauma group (92% vs 11%). There was no statistically signif-cant difference in the presence of ulnar distribution sensoryoss.

Of the 35 cases (30 patients) not associated with trauma,nly 6 presented with intrinsic hand muscle weakness, the most

Table 1: Patie

Characteristics

Total no. involved hands*Symptoms

Sensory changes onlyUlnar distributionNonspecific or median distribution

Sensory plus motor weaknessMotor weakness onlyAsymptomatic (presented with unrelated complaints)

SignsUlnar distribution sensory lossUlnar-innervated muscle weakness/atrophyNo physical examination findings

Bilateral ulnar neuropathy of the wrist (no. patients)Specific ulnar sensory symptomsNonspecific sensory symptomsMotor � sensory symptomsAsymptomatic

Cumulative Stress Identifiable Risk Factors

Repetitive occupational/recreational activityWheelchair, crutch, or walker useCyclingPianistNone

OTE. Values are n or n (%).Represents 42 patients with 47 involved hands.Totals by category do not match total patient sample because 1 pymptoms in 1 hand and nonspecific sensory symptoms in the othe
P�.05 (chi-square test).Not significantly different using the chi-square test.

ommonly reported symptom in the literature for ulnar neu-opathy at the wrist. One of these patients (a bicyclist andculptor) presented with isolated weakness only (a type IV or

lesion), whereas 5 patients had both sensory and motoromplaints. Four of these patients likely had type I lesionswheelchair user, crutch user, ganglion cyst in Guyon’s canalsee later], congenital bilateral elbow synarthoses). The re-aining patient, a pianist, had aching pain in digit V and

solated weakness of the ADQ (an unclassified lesion). None ofhese patients had ulnar abnormalities bilaterally.

The majority of suspected cumulative stress cases presentedolely with sensory complaints (pain, paresthesia, numbness):0 cases (9 patients) had symptoms specifically in the medial.5 digits, whereas 12 hands (9 patients) reported nonlocaliz-ble sensory changes throughout the hand. One patient withilateral ulnar neuropathy presented with specific ulnar sensoryomplaints in 1 hand and nonspecific sensory complaints on theontralateral side. The number of cumulative stress patientsith pure sensory complaints was significantly higher than in

raumatic cases, which rarely presented with sensory com-laints only. Only 5 hands in the specific ulnar sensory com-laint group had a physical finding of decreased sensation. Twohirds of the 9 patients in this group either engaged in aepetitive occupational activity or used a rolling walker. One ofhe patients (a boiler operator) had bilateral ulnar abnormali-ies. The 9 patients with nonspecific sensory complaints repre-ent the group most difficult to classify. Only 1 patient had anyhysical findings (decreased sensation in both ulnar and me-ian distributions). Six patients engaged in repetitive labor orecreational activity. Four of the 9 patients had electrodiagnos-ic evidence of ulnar neuropathy at or distal to both wrists

aracteristics

lative Stress Unitary Trauma Total

35 12 47

2 (63)‡ 1 (8%) 23 (49)10 1 1112 0 12

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8 (23) 4 (33)§ 12 (26)4 (11) 11 (92)‡ 15 (32)5 (71)‡ 1 (8) 26 (55)

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Unitary Trauma Etiology

13 Carpal/metacarpal fracture 63 Wrist surgery 31 Gunshot wound 21 Motorcycle accident 1

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a machine press operator, truck driver, steel cutter, and un-nown occupation).Seven hands presented with symptoms unrelated to sensory

r motor changes and were incidentally found to have ulnarerve abnormalities on electrodiagnostic testing. The present-ng complaints for this patient group included bilateral forearmain, wrist tenderness, metacarpophalangeal joint pain in thepposite hand, opposite-arm numbness, opposite-forearm andand pain and numbness, gait abnormality, and neck pain withace and arm numbness. None of these cases had physicalxamination findings of decreased ulnar sensation or evidencef bilateral ulnar neuropathy.Overall, 71% of hands with an ulnar nerve abnormality not

ssociated with trauma had no abnormal physical examinationndings. Forty percent of these cumulative stress hands had no

dentifiable risk factors for ulnar nerve damage.Of the 12 affected hands associated with unitary trauma, 11

ad hand-muscle weakness with or without sensory com-laints. This was significantly different from the cumulativetress cases at a P value less than .05. All 11 of these caseshowed patterns of signs and symptoms correlating to a specificlassification of ulnar neuropathy at or distal to the wristncluding 5 type I lesions with ulnar distribution numbness andeakness of both hypothenar and hand intrinsic muscles, 2

ype III lesions with weakness of hypothenar and intrinsicuscles, and 4 cases with weakness of hand intrinsics only

either type IV or V, testing did not differentiate). The symp-om pattern in case 12 is not as clearly defined. The patientresented with ulnar-sided hand pain but was noted to haveild FDI atrophy and pain-inhibited weakness on physical

xamination. She was 11 weeks postproximal row carpectomynd radial styloidectomy secondary to Keinböck’s disease. Theack of sensory loss and finding of FDI atrophy suggest a deepotor branch lesion.Electrodiagnostic data are compared between patient symp-

om groups described earlier. The number of patients in each

Table 2: Unilateral Electrodiagnostic Criteria of Ulnar Ne

Criteria

Total no. involved handsDecreased ulnar sensory amplitude across wrist*Prolonged ulnar sensory distal latency across wrist†

Ulnar sensory distal latency � median sensory distal latency �0.5mDecreased ADQ CMAP amplitude across wrist**Prolonged ADQ CMAP distal latency across wrist††

FDI CMAP distal latency across wrist �4.5msFDI CMAP amplitude across wrist �4mVPositive needle electromyographic changes in ADQ or FDIMotor amplitude increase across the elbow �20%Motor conduction velocity change across the elbow �20%Dorsal ulnar cutaneous sensory amplitude �10mV

OTE. Values are positives and number tested. Group 1: presentingigns or symptoms. Group 2: presenting sensory symptoms in a nonroup 3: presenting muscle weakness with or without sensory s

nnervation of the affected hand.SNAP amplitude �10�V if age �60 years and �8�V if age �60 yeSNAP distal latency �3.5ms if age �60 years and �4.1ms if age �Ulnar sensory no-response scored as positive only if a median senOne of 11 cases had median no response or prolonged median SNFive of 12 cases had median no response or prolonged distal latenFour of 17 cases had median no response or prolonged distal latenOne of 7 cases had median no response or prolonged distal latenc
*ADQ CMAP amplitude �6mV for all ages.†ADQ CMAP distal latency �3.5ms if age �60 years and �3.8ms if age
roup fulfilling the 1-sided criteria of ulnar neuropathy at oristal to the wrist is presented in table 2. Prolonged SNAPistal latency from the wrist to digit V was the most frequentlectrodiagnostic abnormality found in the 3 patient groupsithout muscle weakness complaints. Over 90% of the specific

nd nonspecific sensory symptom groups (groups 1 and 2,espectively) had a prolonged SNAP distal latency in the in-olved hand. This abnormality was found in nearly all of theasymptomatic” patients (group 4) as well. However, de-reased SNAP amplitude was present in less than half of theatients in these 3 groups. Motor studies were much lessnformative in these patient groups. None of the patients inroups 1, 2, or 4 had decreased CAMP amplitude to the ADQ.he ADQ CMAP distal latencies were also most commonlyormal in these patient groups: groups 1, 2, and 4 showed arolonged distal latency in less than 20% of cases in all groups.eedle electromyography disclosed ADQ or FDI abnormalities

n 2 of 11 group 1 patients (1 because of coincident chronic8-T1 radiculopathy without recent axonal loss, second witholyphasic neuropathic motor units in FDI). Group 2 hadositive electromyographic findings in 1 of 12 patients (a mildDI abnormality). Only 1 patient in group 1 underwent CMAP

esting to the FDI and was found to have decreased amplitudeith normal distal latency.Among the 17 cases presenting with muscle weakness with

r without sensory symptoms (group 3), 100% had positivendings in the FDI or ADQ on needle electromyography. Eightf the 17 patients had a decreased SNAP amplitude (6 patientsith sensory complaints, 2 without), and 6 of these 8 patients

lso had a prolonged SNAP distal latency. ADQ CMAP testinghowed slowing in 41% and decreased amplitude in 59% ofroup 3 patients. Five patients underwent FDI testing; 3 had aistal latency slowing and 4 had decreased CMAP amplitudes.Comparing patients with no motor symptoms to those withotor symptoms revealed characteristic electromyographicndings (table 3). Patients with motor symptoms were signif-

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cantly more likely to have decreased ulnar motor-evokedmplitude to the ADQ and abnormalities on needle electro-yography. Patients without motor symptoms were more

ikely to have a prolonged sensory distal latency.When the comparison was shifted to patients with cumula-

ive stress and those with traumatic ulnar neuropathy of therist, similar electrodiagnostic differences were noted (table). Patients with traumatic ulnar neuropathy were significantlyore likely to have decreased ulnar sensory and motor-evoked

mplitudes and prolonged ulnar distal latencies. Needle elec-romyographic changes were significantly more common inatients with traumatic ulnar neuropathy of the wrist as well.Comparison of ulnar sensory distal latency and median sen-

ory distal latency in our patient groups was complicated byoexisting median and ulnar sensory abnormalities in the samerist. Nearly half of the patients presenting with nonspecific

Table 3: Unilateral Electrodiagnostic Criteria of Ulnar NeuropathSigns an

Criteria


Ulnar sensory distal latency � median sensory distal latency �0Decreased ADQ CMAP amplitude across wrist¶

Prolonged ADQ CMAP distal latency across wrist#


OTE. Values are positives and number tested.bbreviation: NS, not significant.SNAP amplitude �10�V if age �60 years and �8�V if age �60 yeSNAP distal latency �3.5ms if age �60 years and �4.1ms if age �Ulnar sensory no-response scored as positive only if a median senSeven of 30 cases had median no response or prolonged median SFive of 17 cases had median no response or prolonged distal latenADQ CMAP amplitude �6mV for all ages.ADQ CMAP distal latency �3.5ms if age �60 years and �3.8ms if

Table 4: Unilateral Electrodiagnostic Criteria of Ulnar N

Criteria


Ulnar sensory distal latency � median sensory distal latency �0Decreased ADQ CMAP amplitude across wrist¶

Prolonged ADQ CMAP distal latency across wrist#


OTE. Values are positives and number tested.SNAP amplitude �10�V if age �60 years and �8�V if age �60 yeSNAP distal latency �3.5ms if age �60 years and �4.1ms if age �Ulnar sensory no-response scored as positive only if a median senNine of 35 cases had median no response or prolonged median SNThree of 12 cases had median no response or prolonged distal late
ADQ CMAP amplitude �6mV for all ages.ADQ CMAP distal latency �3.5ms if age �60 years and �3.8ms if age �

ensory complaints had abnormal median sensory conductionn the same wrist (either no response or distal latency �3.7msr 4.3ms depending on age) and were not included in thisnalysis. Of the remaining 7 patients in group 2, only 2 showedn ulnar distal latency 0.5ms greater than the median distalatency in the same wrist. One patient in group 1, 4 patients inroup 3, and 1 in group 4 were not included because ofbnormal median NCSs. Of the remaining included cases, 7 of0 in group 1, 5 of 13 in group 3, and 4 of 6 in group 4 fulfilledhe previously described criterion for comparing ulnar andedian SNAP distal latency.The 4 patient groups were also evaluated by side-to-side

omparison criteria (table 5). Again, for the 33 patient groupsithout muscle weakness, the ulnar motor studies revealed few

bnormalities. Also, across all patient groups, relatively few

he Wrist as Fulfilled by Patient Groups With and Without Motorptoms

No Motor Sign Motor � Sensory P Value

30 1712/30 8/17 NS26/30 8/17 �.05

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ars.response is obtainable.distal latency (�3.7ms if age �60y and �4.3ms if age �60y).

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atients fulfilled side-to-side diagnostic criteria that did notlso fulfill the corresponding unilateral criterion.

Side-to-side comparison is further analyzed in tables 6 and 7.atients with motor symptoms were significantly more likely toave side-to-side ulnar motor-evoked amplitude differences.o other side-to-side difference was noted in comparing pa-

ients with and without motor symptoms. When comparingatients with traumatic etiologies with those with cumulativetress, a side-to-side difference in ulnar motor- and sensory-voked amplitude was significant.

oncurrent CTSAs mentioned earlier, significant numbers of patients exhib-

ted median nerve abnormalities in addition to ulnar abnormal-ties at the time of electrodiagnostic testing. Sixteen of the 47ases met electrophysiologic criteria for CTS in the same hands the ulnar neuropathy: 3 of the 12 unitary trauma cases and3 of the 35 nonunitary trauma cases. The incidence of CTSid not differ significantly between these 2 patient groups. Andditional 3 cumulative stress patients had a remote history ofarpal tunnel release on the involved side. Presenting symp-

Table 5: Side-to-Side Comparison Electrodiagnostic Criteria

Criteria

Total no. patients*Ulnar sensory amplitude difference �50%

(No. of hands fulfilling unilateral sensory amplitude criteria)Ulnar sensory distal latency difference �0.5ms

(No. of hands fulfilling unilateral sensory distal latency criteria)Ulnar motor amplitude difference �50%

(No. of hands fulfilling unilateral motor amplitude criteria)Ulnar motor distal latency difference �1.5ms

(No. of hands fulfilling unilateral motor distal latency criteria)

OTE. Values are positives and number tested. Ulnar sensory nonrTotal number of patients does not add to 42 because one patient iTwo patients not tested bilaterally.Seven patients not tested bilaterally.Four patients not tested bilaterally.Four patients not tested bilaterally.Nine patients not tested bilaterally.Three patients not tested bilaterally.

Table 6: Side-to-Side Comparison Electrodiagnostic Criteria of UWithout Motor

Criteria

Total no. patientsUlnar sensory amplitude difference �50%

(No. of hand fulfilling unilateral sensory amplitude criteria)Ulnar sensory distal latency difference �0.5ms

(No. of hands fulfilling unilateral sensory distal latency criterUlnar motor amplitude difference �50%

(No. of hands fulfilling unilateral motor amplitude criteria)Ulnar motor distal latency difference �1.5ms

(No. of hands fulfilling unilateral motor distal latency criteria

OTE. Values are positives and number tested. Ulnar sensory nonrTwo patients not tested bilaterally.Seven patients not tested bilaterally.Includes 1 patient with bilateral ulnar neuropathy of the wrist.
Eleven patients not tested bilaterally.Nine patients not tested bilaterally.
oms of the ulnar neuropathy of the wrist in the cumulativetress group included both motor and sensory complaints.

urgical FindingsSeven patients were judged to be surgical candidates and un-

erwent Guyon’s canal decompression. The ulnar neuropathytiology was unitary trauma in 5 of the patients (3 carpal fractures,status post–carpal tunnel release surgery, 1 status post–carpal

one surgery) and cumulative stress in the other 2 with 1 second-ry to crutch use and the other being idiopathic. Patient charac-eristics and the electrodiagnostic findings for these surgical pa-ients are presented in table 8. The 2 cumulative stress patientsoth complained of muscle weakness, and needle electromyogra-hy showed spontaneous activity and decreased recruitment ofDI and ADQ in both. Case 1 also showed decreased ulnarensory amplitude with normal conduction velocity and no motorerve conduction abnormalities. The operative report noted noignificant sites of compression or anatomic pathology. Six weeksostsurgery, the patient’s symptoms had resolved. Nerve conduc-ion studies in case 2 revealed a pattern of ulnar motor axonal lossith no sensory abnormalities. A 1-cm ganglion cyst was found

lnar Neuropathy of the Wrist as Fulfilled by Patient Group

Group 1:pecific Ulnar

Sensory Sign

Group 2:Nonspecific

Sensory SignGroup 3:

Motor � SensoryGroup 4:

Asymptomatic

10 9 17 75/8† 5/9 6/10‡ 3/7(4) (5) (5) (2)

3/8 2/9 6/10 3/7(3) (3) (6) (3)

0/6§ 0/5� 6/8¶ 0/4#

(0) (0) (6) (0)1/6 0/5 1/8 0/4(1) (0) (1) (0)

nse scored as positive regardless of testing on contralateral side.resented in both group 1 and group 2.

europathy of the Wrist as Fulfilled by Patient Groups With andor Symptoms

No Motor Sign Motor � Sensory P Value

25 1713/23* 6/10† NS

(11) (5)8/23 6/10 NS(9‡) (6)0/14§ 6/8� �.05(0) (6)

1/14 1/8 NS(1) (1)

nse scored as positive regardless of testing on contralateral side.

of U

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A

rising from the pisotriquetral joint immediately proximal to thealmaris brevis muscle. The cyst was adherent to both the motornd sensory branches of the ulnar nerve. After 8 weeks, she hadmprovement of her symptoms but still experienced residualumbness in her fingertips and grip weakness.

In 2 of the traumatic cases, surgical exploration revealed noignificant pathology or compression. The first patient com-lained only of ulnar-sided hand pain after wrist surgery foreinböck’s disease. The patient had normal motor studies andormal needle electromyography but no evoked response onensory nerve testing. The second traumatic patient with nourgical findings also had a normal needle electromyography ofhe hand intrinsics. Sensory NCS showed reduced amplitudend increased latency, whereas motor NCS showed decreasedmplitude only. Median nerve studies showed distal motor andensory denervation. Preoperatively, the patient complained of

Table 7: Side-to-Side Comparison Electrodiagnostic Criteria of

Criteria

Total no. patientsUlnar sensory amplitude difference �50%

(No. of hands fulfilling unilateral sensory amplitude criteria)Ulnar sensory distal latency difference �0.5ms

(No. of hands fulfilling unilateral sensory distal latency criterUlnar motor amplitude difference �50%

(No. of hands fulfilling unilateral motor amplitude criteria)Ulnar motor latency difference �1.5ms

(No. of hands fulfilling unilateral motor distal latency criteria

OTE. Values are positives and number tested. Ulnar sensory nonrFour patients not tested bilaterally.Five patients not tested bilaterally.Twelve patients not tested bilaterally.Eight patients not tested bilaterally.

Table 8: Comparison of Anatomic Findings With Clinical andDecompre

Ulnar NeuropathyType

Etiology/RiskFactors

ClinicalPresentation Ulnar E

Cumulative stressCase 1 Crutch use Ulnar distal

numbness,weakness

2sensory aWNL; EM

Case 2 None Nonspecificnumbness,weakness

Sensory WNEMG cha

Unitary traumaCase 3 Wrist surgery Ulnar distal

numbnessSensory NR

WNLCase 4 Carpal fracture Nonspecific

numbness,weakness

Sensory WNdistal latechanges

Case 5 Carpal fracture Weakness, digitIV�V clawing

2sensory aamplitudchanges

Case 6 Carpal fracture Nonspecificnumbness,weakness

2sensory alatency; 2EMG WN

Case 7 Carpal tunnelrelease

Digit IV�Vweakness

Sensory WNchanges

OTE. All cases with electromyographic changes involved both the ADQbbreviations: 2, decrease; EMG, electromyographic; 1, increase; NR, n


umbness predominantly in digits II and III and finger abduc-ion weakness. She underwent carpal tunnel release anduyon’s canal release, and 5 weeks postoperative her symp-

oms resolved. Case 4 complained of both motor and sensoryymptoms, but NCS revealed motor abnormalities only. Sur-ery revealed compression of the mixed ulnar nerve under theCU tendon proximal to the pisiform bone. Case 5 complainedredominantly of muscle weakness and digit IV and V clawing,nd NCS showed decreased motor and sensory amplitude withormal latency. Surgery revealed tight, compressive fasciaround the mixed ulnar nerve proximal to its bifurcation overeveral centimeters. Case 7 presented with digit IV and Vlawing and weakness 4 weeks after carpal tunnel releaseurgery on the affected wrist. Sensory NCSs were normal, butotor NCS had no response. Surgical exploration found sig-

ificant scar tissue around the mixed ulnar nerve proximal to

r Neuropathy of the Wrist as Fulfilled by Presenting Etiology

Cumulative Stress Unitary Trauma P Value

30 1213/26* 6/7† �.05

(12) (5)9/26 5/7 NS(10) (5)2/18‡ 4/4§ �.05(2) (4)1/18 1/4 NS(1) (1)

nse scored as positive regardless of testing on contralateral side.

trodiagnostic Findings in Patients Undergoing Ulnar NerveSurgery

diagnosis Data Surgical Findings Outcome

tude; motoranges

None noted Resolved

amplitude ADQ; 1cm ganglion cyst adherent tosensory and motor branch

Residualsymptoms

tor WNL; EMG None noted Residualnumbness

amplitude / 1to ADQ; EMG

Compression under FCUtendon proximal to pisiform

Resolved

tude; 2DQ, FDI; EMG

Diffuse tightness from 4cmproximal to wrist crease tosensory/motor bifurcation

Resolved

tude / 1 distalplitude to ADQ;

None noted Resolved

otor NR; EMG Compression proximal to wristcrease due to significantscar tissue

Resolved

Ulna

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)

espo

Elecssion

lectro

mpliG ch

L; 2nges

; mo

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and FDI.o response; WNL, within normal limits.

tp

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tcfc

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1


he wrist crease. By 7 months postoperatively, she had com-letely recovered ulnar motor function.

DISCUSSIONThe collection of data process for this study revealed some

itfalls to the diagnosis of ulnar neuropathy at or distal to therist. Although ulnar neuropathy at or distal to the wrist haseen well characterized in the literature, it is not as common asther mononeuropathies, like median mononeuropathy at therist. In addition, with common entrapments at the cubital

unnel and above the elbow, there are additional opportunitiesor electrodiagnostic confusion. Future study of ulnar neurop-thy at or distal to the wrist should include better characteriza-ion of electrodiagnostic studies to overcome these pitfalls.ertainly, looking at ulnar sensory and motor conductionscross all potential entrapment sites is necessary. Better under-tanding of the utility of specialized conduction studies andharacterization of the dorsal ulnar cutaneous response in thesentrapments is needed.

In our series, the overwhelming number of patients hadither no symptoms or sensory symptoms only and a normaleurologic examination. This is noted exclusively in our cu-ulative stress patients. This is different from what is other-ise reported in the literature. This difference may be becausef the fact that our series was heavily weighted in number toatients with cumulative stress. Existing literature tends not tonclude the large patient cohort with abnormalities of ulnarerve conduction without specific motor or sensory symptomsr a clear etiology of injury. Individual patients who wouldulfill our criteria for idiopathic or cumulative stress by historyan be found within prior larger case series, but these subjectsere still initially selected on the basis of intrinsic hand weak-ess or ulnar distribution sensory loss. We selected patientsased primarily on electrodiagnostic abnormalities and thenubsequently correlating with clinical history and physical ex-mination. Our selection process resulted in this diverse patientopulation.Our traumatic cases, however, were more reflective of the

resent literature. As presented earlier, available case seriesuggest a distribution of mixed motor and sensory, pure sen-ory, and pure motor lesions of 35%, 11%, and 52%, respec-ively.2,12,15-18 Our sample of traumatic patients followed thisistribution with 50%, 8%, and 42% mixed, pure sensory, andure motor lesions. Expanding the unitary trauma subset tonclude selected cumulative stress patients with specific riskactors for ulnar neuropathy of the wrist (cycling, crutch use,heelchair use) added 2 cases of a mixed lesion, 1 pure motor

esion, and 1 pure sensory lesion. This expanded patient subsetrom our study replicates the characteristic findings of theresent ulnar neuropathy literature.Patients with traumatic causes of ulnar neuropathy of the

rist tend to have motor symptoms. Patients with cumulativetress tend to have no symptoms or sensory symptoms only.his is paralleled in the physical examination in which mostatients with cumulative trauma have a normal examination,hereas patients with traumatic etiologies have weakness.lectromyography confirms these changes by noting sensorynd motor-evoked amplitude changes in patients with traumaticlnar neuropathy of the wrist. Those from cumulative stress orith sensory signs only have more variable electrodiagnosticndings without motor changes.Sixteen of 47 (34%) cases of ulnar neuropathy at or distal to

he wrist in this series also had electrodiagnostic evidence of aoncurrent median neuropathy at the wrist. No significant dif-erence of CTS incidence was found between the traumatic and
umulative stress cases of ulnar neuropathy of the wrist. Pre-
ious studies19,20 have estimated the incidence of ulnar nerveensory action potential abnormalities in established cases ofTS at 18% to 41%. Several explanations for the association oflnar nerve sensory abnormalities and CTS have been sug-ested: an underlying subclinical neuropathy predisposing tontrapment neuropathies19 or an anatomic abnormality causingimultaneous narrowing of both canals.11 Of note, the mostommon electrodiagnostic pattern of ulnar neuropathy of therist in the cumulative stress patients (prolonged sensory distal

atency with normal sensory amplitude and normal motor stud-es) followed the initial pattern of median neuropathy in mildTS. Despite anatomic differences between the carpal tunnelnd Guyon’s canal, a similar pathophysiology may account forhe electrodiagnostic similarities between carpal tunnel syn-rome and cumulative stress ulnar neuropathy as seen in thiseries. Further studies are required to determine the etiology oferve damage in cumulative stress at Guyon’s canal.Anatomic study of penetrating and surgical cases showed

ome findings different from those previously reported in theiterature. These include the presence of ulnar nerve compres-ion proximal to Guyon’s canal by the FCU over the pisiformnd by compressive fascia proximal to Guyon’s canal. Inter-stingly, 4 of the 7 cases resulted in the surgical findings noteing predicted by the electrodiagnostic findings. Further pro-pective evaluation of the electromyographic findings of thisisorder should keep in mind this discrepancy.

CONCLUSIONSRecommendations of prospective study should include more

etailed electrodiagnostic evaluation. This should include con-istent use of the dorsal ulnar cutaneous sensory response, these of inching technique, and the consistent use of motoronduction to the ADQ and FDI. This would allow interpreta-ion of the utility of these studies in this disorder. Studyingatients with sensory complaints is especially important be-ause our study indicated that this group was electrically het-rogeneous. More rigid and extensive testing might revealome more helpful trends.

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