J Manipulative Physiol Ther 2003 (Nov); 26 (9): 602–607 ~ FULL TEXT
Brent S. Russell, DC
Life University Research Center,
Marietta, Ga, USA, and
Private practice of chiropractic,
Atlanta, Ga, USA
BACKGROUND: There has been little published about ulnar tunnel syndrome (UTS) as it relates to the practice of chiropractic, despite chiropractors' apparent interest in nerve compression syndromes and a growing trend toward providing chiropractic extremity care. This syndrome is not very common and could be mistaken for carpal tunnel syndrome by practitioners who are not aware of the differences.
OBJECTIVE: To discuss the case of a patient with ulnar tunnel syndrome whose symptoms were resolved by chiropractic extremity adjustment.
CLINICAL FEATURES: A 45-year-old female patient complained of numbness in her little finger. Standard orthopedic testing procedures for the wrist and hand reproduced the symptom, but tests for the cervical spine and thoracic outlet region were negative
INTERVENTION AND OUTCOME: Care for this patient consisted of adjustment procedures directed to the wrist, primarily the hamate and pisiform articulations with the triquetrum. Her symptoms were resolved in 4 office visits, with corresponding improvement in examination findings.
CONCLUSION: This case report represents what a patient could expect during a typical chiropractic treatment. The examination and the care given were simple and cost-effective but might not be sufficient for a more complicated or persistent case. The costs for the care in this case were borne solely by the patient and were affordable. Hard conclusions cannot be reached without more sophisticated diagnostic procedures, additional similar cases, and controlled research conditions.
From the Full-Text Article:
The ulnar tunnel (also known as Guyon's canal) lies at the level of the proximal carpal bones along the ulnar border. The transverse carpal ligament (TCL), or flexor retinaculum, forms the floor of the tunnel, with the aponeurosis of the flexor carpi ulnaris muscle forming the roof (Fig 3).
The ulnar border is formed by the pisiform; the tunnel is triangular in shape and the radial border is defined where the FCU aponeurosis attaches to the TCL. The radial border is often described incorrectly as being formed by the hook of the hamate, but no portion of the tunnel actually attaches to that bone.  The ulnar artery and veins pass through the tunnel along with the palmar branch of the ulnar nerve, which subsequently splits into superficial and deep branches (Fig 4).
The deep branch innervates the hypothenar muscles, the 2 lateral lumbricals, all of the interossei muscles, the adductor pollicis muscle, and the deep head of the flexor pollicis brevis muscle. The superficial branch innervates the palmaris brevis muscle, the palmar skin of the fifth finger, and the ulnar skin of the fourth finger. It is possible to have either sensory or motor symptoms, or both, depending on exactly how and where the nerve is affected.  The symptoms may be worse at night, there may be hypothenar atrophy, and the patient may complain of difficulty with hand movements. Phalen's sign (sustained, forced flexion of the wrist) and reverse Phalen's sign (also called “Prayer Sign” or Wormser's sign: sustained, forced extension) are CTS tests which may also reproduce UTS symptoms. Pecina et al1 provide a description of this and other nerve compression syndromes that the practicing doctor will find useful. Pecina et al1 state, in contradiction to the findings for the patient above, that in UTS adduction of the fifth finger will not be impaired. This statement seems curious, given that the deep branch of the ulnar nerve supplies the interossei muscles and that the palmar interossei muscles perform adduction of the fingers, including the fifth finger. 
How is the nerve affected? There have been a number of causative factors documented for UTS, including fracture of the hook of the hamate,  bipartite hamulus,  giant cell tumor of tendon sheath,  and ulnar artery aneurysms,  pathological causes in which chiropractic intervention or manipulation of any sort not only seems clearly inappropriate but also possibly harmful. Some sports activities are associated with the syndrome: long-distance bicycling can cause prolonged compression of the nerve, [13, 14] with the rider either keeping the wrists in extension or resting the ulnar portion of the hand on the handlebars; and repeated trauma from the handle of a baseball bat or hockey stick or karate blows may affect it.  Other sources of constant or repeated blows to the palm causing ulnar neuropathy may include construction work and the use of hammers, pneumatic drills, and vibrating tools.  There also have been cases involving pisotriquetral joint arthritis,  ganglions,  and edema.  The above causes are similar to reports describing nerve compression syndromes in other parts of the body, for which, like UTS, there have also been a number of idiopathic cases.
There has been little written or research conducted on idiopathic ulnar tunnel syndrome, and there is no established explanation as to why a manipulative thrust to the hand would affect compression of the ulnar nerve, whatever the cause. Most discussion about the mechanism of adjustment has focused on spinal joints. Lantz  addresses a number of aspects of the vertebral subluxation complex, some of which would also apply to extremity joints. He suggests that manipulation can be an effective means of managing edema related to inflammation. Is it possible that the patient described above experienced a seemingly minor, and therefore forgotten, injury to her hand? If so, it may be that swelling of an articular capsule adjacent to the tunnel was the source of compression of the nerve, and this was reduced by the adjustments.
It is also possible that the apparent joint fixation and subsequent improvement in mobility were somewhat incidental to the sensory and motor improvements. Sucher  offers magnetic resonance imaging (MRI) documentation that osteopathic manipulation may stretch the transverse carpal ligament, thus relieving pressure within the carpal tunnel. This explanation almost certainly would also apply to the ulnar tunnel, since surgical release of the TCL intended to treat CTS has been observed to relieve pressure in the ulnar tunnel as well.  This may be particularly significant to the adjustment of the pisotriquetral joint described above. It should be noted that the pisiform, though anatomically part of the proximal row of carpal bones, does not actually play a role in articular movements of the wrist; instead, it functions primarily as a sesamoid bone enhancing the moment arm of the flexor carpi ulnaris muscle.  It also is the attachment point of the ulnar end of the TCL and, indirectly, the aponeurosis of the flexor carpi ulnaris muscle—the floor and roof of the ulnar tunnel. Schafer and Faye  proposed that “ligamentous fixations” (ligament shortening) are the cause of restricted bone movement in some instances. They suggest that, in such a situation, adjustive thrusts may lengthen the ligament but will improve the restricted mobility only slightly. While this concept is not established, it does seem to parallel the claim by Sucher.  Given the limited degree of articulation that the pisiform has with the triquetrum, it may be that a perceived loss of mobility in that joint may be more of a ligamentous phenomenon than an articular restriction and that manipulation of this joint may have more to do with the soft tissue attachments than the joint itself.
Conservative medical treatment for UTS would typically include avoidance of repetitive trauma, splinting, local corticosteroid injection, and anti-inflammatory medications, assuming that any other underlying diseases causing the nerve compression had been addressed. Muscle atrophy or persistence of symptoms past 6 months, with or without care, would be indications for surgical decompression,  since prolonged compression will eventually cause permanent damage to the nerve.
The above case is probably not unique, nor even unusual, for a chiropractic practice. There are many anecdotal reports of patients coming in with similar symptoms for which the Doctor of Chiropractic in general practice may not have had the expertise to make a specific diagnosis. The effects of chiropractic adjustments seem, in many cases, to be general enough that many symptoms will clear up with care—or perhaps on their own, with time—despite the lack of a specific approach, fortunately for both parties involved. Of course, in a more persistent or severe case, the doctor should make a referral to a specialist. For practical considerations, however, it is important to note that additional diagnostic studies or referral to a neurologist would also mean significant additional expense. For the above patient, who paid cash and had no insurance coverage for chiropractic care, the examination and care rendered involved 4 office visits and a total cost of only $168 (USD).
There certainly are unanswered questions in this case. How valid were the examination findings? No attempt was made to quantify the degree of tenderness in the hand using any sort of measurement device, such as a pressure algometer; the assessment was subjective but based on experience. No measurement device, such as a dynamometer, was used to evaluate muscle weakness. However, Brandsma et al  studied manual muscle strength testing of the hand with patients who had neuropathy involving the ulnar and median nerves, and intraobserver reliability was found to be good to very good.
An assumption was made that the location of the problem was the ulnar tunnel; further examination could include radiographs or MRI of this area to evaluate for fractures, osteophytes, scar tissue, tumors, masses, and inflammation. As it is, although the patient's symptoms seem to have improved from the carpal manipulation, it is still not clear exactly what the cause of the symptoms was or what exactly the adjustments accomplished. The lack of positive findings of the cervical and thoracic outlet tests does not necessarily rule out involvement in either of these areas, since the orthopedic tests used have a limited degree of sensitivity. There are many anecdotal reports from chiropractors who claim to be able to help carpal tunnel syndrome using cervical manipulation alone. Since at least some of these are probably cases of cervical radiculopathy misdiagnosed as CTS, we should be reminded of the significance of understanding the syndromes we work with and the importance of a good examination.
Most practitioners would find it reasonable, in cases such as the one above, to proceed with a trial of care based on the findings. However, without confirmation by nerve conduction velocity (NCV), this case remains a diagnostic impression of UTS, thus suspected ulnar tunnel syndrome, rather than a true diagnosis. No method of measurement of the suspected nerve dysfunction was made; NCV, electromyography (EMG), or somatosensory evoked potential (SSEP) studies could be appropriate in such a case. NCV is considered to be the “gold standard” for confirmatory diagnosis of CTS and would be for UTS as well.
Peripheral nerve compression syndromes represent a category of problems that chiropractors sometimes claim to be able to help but for which there is only scant documentation. The case above lacks many of the controlled conditions of a research study, so it is difficult to draw hard conclusions. While a clinical trial of a number of patients would provide better information, it also may be difficult to accomplish, since this is not a particularly common syndrome. I hope that this initial report will contribute to further understanding of similar conditions and the use of conservative manipulative approaches in their resolution.