Klippel–Feil Syndrome with Sprengel Deformity and Extensive Upper Extremity Deformity: A Case Report and Literature Review

Introduction Klippel–Feil syndrome (KFS) is a congenital anomaly resulting from fusion of cervical vertebral bodies secondary to the dysregulation of signaling pathways during somite development. It is commonly associated with scoliosis and Sprengel deformity. We present a case of KFS with commonly associated abnormalities as well as deformities that have not yet been reported in the literature. Case Presentation A 3-year-old girl presented for further evaluation of a left upper extremity deformity following a negative genetic workup. Upon physical exam and radiographic imaging, the patient was diagnosed with KFS and associated abnormalities including cervical scoliosis, Sprengel deformity, and congenital deformity of the left upper extremity. Deformities of the left upper extremity include radioulnar synostosis, a four-rayed hand, and absent thenar musculature. The Sprengel deformity was corrected surgically with a Woodward procedure. Discussion Congenital musculoskeletal deformities can be differentiated based upon spinal and limb embryology. The presence of extraspinal abnormalities not originating from somite differentiation may suggest a severe form of KFS. Important considerations in the workup of the KFS patient include looking for deformities of the shoulder girdle and upper extremities to identify abnormalities for intervention at a young age.


Case Presentation
e patient is a 3-year-old girl from China who initially presented with an ongoing diagnosis of left upper extremity deformity. Previous radiographs showed a deformity within the left forearm and hand, but left radial aplasia was excluded. Holt-Oram syndrome was previously excluded due to the lack of cardiac malformations and, more de nitively, the lack of mutations within the TBX5 gene. Klippel-Trenaunay syndrome was previously excluded due to the lack of a portwine stain or other vascular malformations and the absence of limb or tissue overgrowth. Previous genetic testing revealed no mutations within the PIK3CA gene, making Klippel-Trenaunay syndrome unlikely.
Physical examination demonstrated a left hand with only four digits, likely from congenital fusion of the rst and second digits which functioned as a thumb, opposing to the fth digit with very good strength. e patient's left forearm measured 2 centimeters shorter than the right with apparent synostosis of the left proximal radioulnar joint. Additionally, the left humerus measured 3 centimeters shorter than the right. e patient was unable to undergo passive pronation or supination of the hand with preserved exion and extension at the elbow joint. Examination of the patient's back demonstrated a symmetrically higher left scapula with a hard prominence palpable at the cervicothoracic junction.
Initial outside radiographs of the cervical, thoracic, and lumbar spine demonstrated mild scoliosis of the cervical spine. Further imaging revealed partial fusion of the left cervicothoracic spine from C4 to T1 (Figure 1). Elevation of the left scapula with an associated omovertebral bone was also noted (Figures 2 and 3). ese ndings are consistent with Klippel-Feil syndrome with an associated Sprengel deformity. Additional imaging of the left upper extremity con rmed a proximal radioulnar synostosis ( Figure 4). Incidental ndings included a left cervical rib and tracheal bronchus. e patient su ered no hearing impairment and no congenital cardiac or genitourinary defects upon further workup. Although genetic testing to further support a diagnosis of KFS was o ered, the parents of the patient declined, since the immediate treatment plans would remain unchanged regardless of the results. Additional conditions considered in the patient's di erential diagnosis included Poland syndrome and MURCS (müllerian duct aplasia-renal aplasia-cervicothoracic somite dysplasia) association; however, these were unlikely due to the lack of symptomology classically associated with the musculoskeletal deformities seen in each condition.

Discussion
Klippel-Feil syndrome was described over 100 years ago by Maurice Klippel and André Feil. However, opinions regarding associated abnormalities and treatment options are still evolving [2,3]. e classic cervical vertebral abnormalities of KFS are well known and associated with derangements within the signaling pathways during paraxial mesoderm di erentiation and somite development [12]. e literature also reports occurrences of KFS with common associated anomalies. Our case is unique due to the multiple extraspinal manifestations identi ed in a single patient, including Sprengel deformity and signi cant left upper extremity deformities such as proximal radioulnar synostosis and a four-rayed hand without thenar musculature. To the best of the author's knowledge, oligodactyly with absence of thenar musculature has not yet been reported with KFS.
Cervical scoliosis, which is the most common associated abnormality with KFS, was seen in the case presented. e patient also demonstrated partial fusion of the left cervicothoracic spine from C4 to T1 (Figure 1). Vertebral anomalies at the cervicothoracic junction are secondary only to the C2-C3 junction in prevalence of fusion anomalies [15]. e classi cation system recently proposed by Samartzis et al. de nes the cervical spine fusion patterns for patients with KFS. e classi cation is determined radiographically such that Type I patients are de ned as having a single congenitally fused cervical segment. Type II patients have multiple, noncontiguous congenitally fused segments, and Type III patients have multiple contiguous, congenitally fused cervical segments [16]. Under this proposed classication, our patient would be classi ed as a Type III KFS.  No surgical intervention, such as disc arthroplasty or fusion of unstable adjacent cervical spine levels, was indicated for our patient, since neurologic symptoms to suggest radiculopathy or myelopathy were not evident. However, Type III KFS patients do have increased risk of developing radiculopathic or myelopathic symptoms when compared to Type I and II patients [16]. Typical age of onset of spinerelated neurologic symptoms is between 10 and 11 years of age for KFS patients when the disorder is identi ed in childhood. However, patients with milder forms of KFS not detected in childhood can present with neurologic symptoms into their 40s [16][17][18]. For this reason, the patient was encouraged to continue routine follow-up to evaluate for future development of neurological de cit.
In addition to cervical scoliosis, the presence of a Sprengel deformity was identi ed. is deformity, the second most common deformity associated with KFS, was rst described by Eulenberg in 1863 [13,19]. Years later, others described cases of the congenitally elevated scapula, but it was Otto Sprengel who described the pathology and proposed a theory of its existence in 1891 [20,21]. e accepted cosmetic classi cation of Sprengel deformity, the Cavendish classi cation, was proposed in 1972 [22]. e Cavendish classi cation system proposed grades based on the deformity. Grade 1 is described as a very mild deformity that is not noticeable when the patient is dressed. Grade 2 is described as a mild deformity that is visible as a lump in the web of the neck when the patient is dressed. Grade 3 is a moderate deformity described as an easily visible deformity with the shoulder joint elevated 2-5 centimeters. Grade 4 is a severe deformity with shoulder joint elevation greater than 5 centimeters or evidence of the superior angle of the scapula near the occiput with or without webbing. Grading can be di cult because of the variation in appearance within a single grade. Although this classi cation does not consider function, it is utilized in the management of the deformity for objective di erentiation when surgical intervention is necessitated to correct both appearance and function.
In the case of our patient, the left shoulder was elevated with scapular elevation to the level of C4-5 on CT imaging (Figure 2), translating clinically to a Grade 3 Sprengel deformity according to the Cavendish classi cation. e undescended scapula seen in Sprengel deformity is at times xed in place to the adjacent vertebra by a pathognomonic omovertebral bone or brocartilaginous bridge preventing necessary scapular rotation during arm abduction past 90° (  Figure 3) [23]. e arm is often unable to abduct and continue over the head due to the downward-facing glenoid cavity which may develop in the setting of a severely malrotated scapula. e treatment for Sprengel deformity depends on the severity of the abnormality. For mild deformities classi ed as Cavendish Grades 1 and 2, nonsurgical options including physical therapy, stretching, and continued observation are most bene cial for the prevention of torticollis and decreased range of motion. Moderate and severe deformities that fall into the higher Cavendish classi cation grades are candidates for surgical intervention. Many surgical procedures for Sprengel deformity correction have been discussed in the literature, but the hallmark techniques involve resection of the omovertebral bone, if present, with caudal relocation of the scapula. Two of the most popular procedures are the Green's and Woodward procedures.
Green's procedure entails detaching muscles from their scapular insertion, elevating the trapezius muscle, and detaching the supraspinatus from the scapula followed by excision of the omovertebral bone. e supraspinous fossa of the scapula is resected, while being cautious not to injure the suprascapular neurovasculature, and the latissimus dorsi and serratus anterior are detached from the scapula as well. Once the scapula is descended to the corrected position, the muscles are reattached to it. Modi cations have been made to the initial Green's procedure including a clavicular osteotomy to reduce the risk of brachial plexus injury, dissection of the insertion of the serratus anterior, and suturing of the inferior pole of the scapula to the thoracic cage into a pocket of the latissimus dorsi muscle [24]. e Woodward procedure was described in 1961 and is often the operation of choice for deformity correction. e procedure involves detaching the trapezius, rhomboid, and levator scapulae muscles at the midline origin followed by removing the omovertebral bone. Next, prominent bony portions of the scapula are removed as well, as the scapula is pulled downward and the muscle attachments are reattached distally to help secure the lowered scapula [25].
Surgical correction is recommended at a young age, usually between 3 and 8 years. However, a few studies have suggested that age does not in uence outcomes [26,27]. Since a higher-grade Sprengel deformity limits the patient's function by impeding necessary rotation of the scapula and shoulder girdle, surgical correction of the Sprengel deformity was indicated in our patient. Surgical correction would improve both function and aesthetics.
Limitations and complications speci c to the surgical procedures for Sprengel deformity correction include hypertrophic scarring, regrowth of the resected bone, neurologic injury to the brachial plexus, and scapular winging [28][29][30][31][32]. Although cosmetic and functional improvements are not always optimally restored to normal, the improvements seen in the aesthetics and function of the scapula can be very signi cant. e mean arm abduction improvements in studies with correctional surgery for Sprengel deformity have been reported between 49°and 77°. Additionally, the mean improvement of Cavendish grading has been reported from 1.5 to 2.0 grades lower in follow-up studies after surgical correction [28,[33][34][35][36][37][38]. e Sprengel deformity was not the only musculoskeletal abnormality resulting in physical limitation. e patient's left upper extremity syndactyly and proximal radioulnar synostosis ( Figure 4) only allowed for exion and extension at the elbow joint. Pronation and supination were not possible secondary to the proximal radioulnar synostosis that kept the left arm xed in 10 degrees of pronation. Surgical correction to restore pronation and supination, however, was not advised. Surgical correction for congenital radioulnar synostosis is rarely indicated except in cases of severe deformity (i.e., ≥60°of pronation) due to high recurrence rates and therefore was not performed [39][40][41].

Conclusion
Congenital musculoskeletal deformities can be di erentiated based on mechanisms of spinal and limb embryology. e presence of extraspinal manifestations, not originating from somite di erentiation, may be indicative of a more severe form of Klippel-Feil syndrome. Important considerations in the workup of the KFS patient include looking for deformities of the shoulder girdle and upper extremities. Identifying these associated abnormalities early is paramount to assess for potential surgical intervention at a young age.

Conflicts of Interest
e authors declare that they have no con icts of interest.