50-year-old man with "poorly localized bilateral shoulder pain and paresthesia in the affected extremity" with nondermatomal distribution.
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The patient came complaining of terrible pain on both shoulders. Furthermore, he referred "pins and needles" in his right arm. MRI was performed in order to make an accurate diagnosis, MRI sequences and plane orientation: Sagittal FSE T1wi, Coronal Fat saturation dual PD-FSE T2wi , Coronal Fat saturation FSET2wi , Axial FSE T2*wi.
MRI showed clear fatty atrophy of teres minor accompanied by a decreased volume of muscle tissue. Muscle atrophy is shown as hiperintensity on FSE T1 and FSE T2 images in between the muscles fibbers that turn hypointense on Fat saturation images.
Degenerative changes in glenohumeral articulation were also seen such as: osteophytes, subchondral sclerosis, subchondral cysts...
The initial description of quadrilateral space syndrome by Cahill and Palmer stated that clinical manifestations include poorly localized shoulder pain, paresthesia in the affected extremity in a nondermatomal distribution, and discrete point tenderness in the lateral aspect of the quadrilateral space. The diagnosis may be difficult to make on the basis of clinical grounds alone and may be confused with rotator cuff tear or impingement on a clinical basis. MRI findings of teres minor atrophy or abnormal signal may be present in as many as 0.8% of patients referred for shoulder MRI. However, most of these patients have other shoulder abnormalities on MRI apart from atrophy or abnormal signal in the teres minor or deltoid muscles or both. In addition, the diagnosis of quadrilateral space syndrome was not suspected clinically before imaging in most of cases.
Because Quadrilateral Syndrome is not clinically suspected and the presence of other shoulder abnormalities the relationship between muscle atrophy and patients symptoms is difficult.
Fatty infiltration is defined as abnormal deposition of fat diffusely within a muscle. Fatty infiltration occurs in the late stages of many pathologic conditions involving skeletal muscle or myotendinous junction injuries, secondary to steroid use or late stages of muscles denervation. MR images reveal increased quantities of fat with its characteristic signal intensity within the involved muscle, usually with a decreased volume of muscle tissue.
In our patient, the lack of intra-articular shoulder derangements and the typical and isolated location of teres minor fat infiltration permitted the diagnosis of quadrilateral space syndrome. Causes of quadrilateral space syndrome: anterior shoulder dislocation, proximal humeral fracture, brachial neuritis, mass lesion (i.e:glenoid labral cyst), compresive forces (fibrous bands in young patients...), however most of the times is idiopathic, as in our patient.
Conclusion:
Quadrilateral Space Syndrome with teres minor fat atrophy without tendon or intraarticular derangement
Final Diagnosis
Quadrilateral space Syndrome.
Quadrilateral space Syndrome.
The MRI examination primarily shows an abnormal signal in the posterior-superior portion of the right shoulder, most notably in the teres minor muscle region, with a clear indication of fatty infiltration. The teres minor muscle appears reduced in volume, and the muscle fibers are replaced unevenly by higher signal intensity fatty tissue. No other significant structural abnormalities are observed in the shoulder joint, including the supraspinatus, infraspinatus, rotator cuff tendon integrity, or the glenoid labrum. There is no evident fracture or local bony destruction in the humeral head or the glenoid of the scapula. No obvious joint effusion is seen in or around the shoulder joint.
Based on the patient’s clinical presentation (bilateral shoulder pain and sensory disturbances in the affected limb, typically non-dermatomal) and the MRI findings of fatty infiltration in the teres minor, the following diagnoses should be considered:
Taking into account the patient’s age, symptom characteristics (discomfort around the shoulder joint, upper limb sensory disturbances), MRI findings indicating isolated fatty infiltration of the teres minor without other significant structural damage, and ruling out other common shoulder disorders, the most likely diagnosis is:
Quadrilateral Space Syndrome.
Treatment for Quadrilateral Space Syndrome is primarily conservative, supplemented by rehabilitation exercises and targeted physical therapy. If a cyst, tumor, or fibrous band is clearly causing nerve compression, surgical decompression may be considered.
Throughout rehabilitation, adjust the intensity and frequency of training according to the patient’s level of pain or discomfort. If severe pain or worsening neurological symptoms occur, seek medical evaluation promptly.
Disclaimer: This analysis report is for reference only and cannot replace in-person consultation or professional medical advice. If you have any doubts or if symptoms worsen, please seek medical attention or consult a specialist promptly.
Quadrilateral space Syndrome.
