Neuropathic arthropathy of the wrist revealing a syringomyelia

Abstract

Syringomyelia is uncommonly revealed by a neuropathic arthropathy (Charcot joint) and characterised by its slow progression with late neurological symptoms. In this particular field, neuropathic arthropathies mainly affect the shoulders and the elbows.

We report a new case of neuropathic arthropathy of the wrist caused by syringomyelia, because of the rarity of this condition as well as its uncommon location.

Neuropathic arthropathy caused by syringomyelia is poorly published in the literature. This atypical entity should be considered in case of Charcot arthropathy associated with neurological loss, especially when it affects the upper limbs.

Background

Neuropathic arthropathy (NA), also known as Charcot joint, is a chronic form of degenerative arthropathy with destructive and productive articular abnormalities, caused by an underlying neurological disorder.^1–3 This condition is resulting from decreasing or loss of proprioception, pain and temperature sensation with progressive disorganisation in the architecture of the affected joint.^{1 4 5}

The main symptoms of NA are painless joint swelling and joint stiffness. Neurological manifestations are often occult and arise later than articular symptoms. Typical imaging findings include joint destruction, disorganisation and effusion with osseous debris.²

NA is a multifactorial disease that can be seen in many entities that lead to neural damage, especially diabetes mellitus, syringomyelia, chronic alcoholism and tabes dorsalis.^1–7 NA is diagnosed in 20%–30% of all cases of syringomyelia, among whom 80% occur in the upper extremity.1 4 5 7 The most frequently affected joints are the shoulders and elbows in syringomyelia, the ankles and feet in diabetes mellitus, the hips and the knees in tabes dorsalis.²

Syringomyelia is a degenerative disorder of the spinal cord characterised by abnormal longitudinal cavitation filled by cerebrospinal fluid within the spinal cord. This cavitation, called a syrinx, can expand and elongate over time, destroying the spinal cord.^{1 5 6} It is commonly located in the lower cervical and upper thoracic segments, and may propagate proximally.^{3 6 7} The damage to the spinal cord may lead to pain, paralysis, weakness and stiffness in the back, shoulders and extremities. These symptoms begin usually in young adulthood.^{6 7}

We report an unusual location of an NA revealing syringomyelia.

Case presentation

A female in her 50s was referred to our department for swelling of the right wrist evolving for 12 months without any trauma or fever, associated with tingling numbness in the right upper limb and chronic neck pain. Her medical history was significant for iron deficiency anaemia.

Physical examination revealed swelling and deformity of the right wrist with an ulnar drift as well as a reduced range of motion and amyotrophy of the first commissure of the hand (figure 1). The wrist was not painful. She had multiple burn scars in the dorsal aspect of the right wrist. There was an abolition of biceps tendon reflex on the right side, and dissociative anaesthesia in the right upper limb and hemi-trunk affecting pain and temperature senses and preserving proprioception. There were not any signs of involvement of the other joints.

Figure 1.

Clinical photos of the patient revealing a swelling and a deformity of the right wrist.

Investigations

Laboratory investigations included a normal leucocyte count, a normal erythrocytes sedimentation rate and C reactive protein, normal blood glucose and a negative syphilis serology (venereal disease research laboratory and treponema pallidum haemagglutination). The patient also had a negative rheumatoid factor, anticitrullinated peptide antibodies and antinuclear antibodies.

Plain radiographs of the right wrist showed a destructive arthropathy of the wrist, with multiple osteophytes (figure 2). CT scans demonstrated diffuse bone resorption with multiple subchondral cysts in the distal extremity of the radius and ulna, joint space narrowing of the radiocarpal joint and the intercarpal joints, as well as marginal hypertrophic osteophytes of the distal ulna (figure 3). Medullar MRI revealed a cervicothoracic syringomyelia associated with Chiari type I malformation (figures 4 and 5).

Figure 2.

Anteroposterior plain radiograph of the right wrist demonstrating narrowing of the joint space, subchondral condensation and hypertrophic osteophytes of the distal ulna.

Figure 3.

Frontal CT scans of the right wrist showing multiple subchondral cysts, global joint space narrowing and marginal hypertrophic osteophytes.

Figure 4.

Sagittal MRI revealing a syrinx extending from C1 to the thoracic region with Chiari malformation type I.

Figure 5.

T2-weighted sagittal MRI of the cervicothoracic syrinx.

Treatment

Decompressive surgery was indicated but refused by the patient. Immobilisation of the wrist with a splint cuff was prescribed.

Outcome and follow-up

At the last follow-up of 12 months, there were no obvious changes in the symptoms of the wrist arthropathy or signs of involvement of other joints.

Discussion

NA secondary to syringomyelia is a rare condition with only few reports in the previous literature. It is quite uncommon in developed countries contrary to endemic areas for syphilis and lepromatous leprosy.⁸ Worldwide, the most common cause of NA is tabes dorsalis.⁸ In European countries, diabetes mellitus, medullar traumas, syringomyelia and ulcero-mutilating neuropathies are more frequent, since neurosyphilis became very rare.⁹

NA is seen in 20%–30% of all cases of syringomyelia.^{1 4–6} NA may inaugurate and reveal the disease, but at late stages.^{1 4–6} Syringomyelia is often combined with Chiari malformation, but can also result from other medullar diseases such as tethered spinal cord, meningomyelocele and myelodysplasia.²

NA secondary to syringomyelia is often located in the upper limb (80%), given that syringomyelia commonly affects the lower cervical and the upper thoracic segments of the spinal cord.^{1 4 6} The arthropathy affects the shoulder at first, then the elbow, the wrist and the interphalangeal joints.² Sternoclavicular and acromioclavicular joints, as well as the lower limbs, are exceptionally involved.⁷

To our best knowledge, syringomyelic NA of the wrist, as the only affected joint, has been reported in only one case report according to which there was a simultaneous involvement of the shoulder, the elbow and the third metacarpophalangeal joint (table 1).1–3 5–7

Table 1.

Literature review

Author (year)	Number of patients	Location	Follow-up (months)	Syringomyelia management	Charcot arthropathy management	Evolution
Ekim and Armağan (2007)1	1	Shoulder, elbow, 3rd MCP	–	Operative	Conservative	–
Deng et al (2013)2	12	16 joints: 10 shoulders, 3 elbows, 1 wrist, 2 IP	39	Operative (5 cases)	–	Favourable
				Non-operative (7 cases)	–	Unfavourable (5 patients)
Grahovac et al (2011)3	1	1 shoulder	72	Operative	–	Favourable
Panagariya and Sharma (2012)5	1	2 shoulders	24	Conservative	Conservative	Favourable
Vikram (2015)6	1	1 shoulder	–	Conservative	Conservative	Favourable
Atalar et al (2010)7	5	6 shoulders	26	Operative (4 patients)	Conservative	Favourable (3 patients)
				Non-operative (1 patient)	Operative (arthroplasty)	Unfavourable
Our report	1	1 wrist	12	–	Conservative	Favourable

IP, interphalangeal joint; MCP, metacarpophalangeal joint.

In our report, the wrist was the only affected joint by NA.

The diagnosis of syringomyelia should be considered in case of dissociative anaesthesia, in which proprioception and motor function are preserved, while pain and temperature senses are lost. These sensory deficits are thought to induce NA.^{1 3 6} According to Deng et al’s report, the loss of pain and temperature senses may involve the ipsilateral trunk.² Clinical symptoms of syringomyelia also include areflexia, muscle weakness and amyotrophy.^{1 3 6}

According to previous studies, symptoms related to neuropathic joints usually appear earlier than neurological symptoms, which are occult and discreet. Therefore, the work-up of every patient who presents with painless joint destruction must include a thorough history of neurological dysfunctions as well as a careful neurological examination.^{2 5 6}

Regarding radiological features, suggestive findings of NAs look like those of tabes dorsalis. However, they are rarely bilateral and symmetrical with a lower rate of periarticular pathological fractures. Hypertrophic and atrophic radiological findings are believed to be two natural stages of this disease although bone resorption seems to be much more common in Charcot joints.^{2 3} In addition to a marked bone destruction, imaging investigation may demonstrate soft tissue swelling, joint space narrowing, condensation of subchondral bone with fragmentation and intra-articular calcification, new heterotopic bone formation and joint subluxation.^1–4 Imaging findings may change according to the site of the arthropathy. While resorption of the epiphysis is classic in the shoulder, hypertrophic changes are habitual in the elbow and the medial extremity of the clavicle. In our report, there were hypertrophic changes without resorption of the epiphysis or subluxation. However, there were multiple subchondral bone cysts in the distal radius and ulna combined with joint space narrowing. We think that syringomyelic arthropathy of the wrist is characterised by the predominance of bony construction and osteosclerosis, while destructive changes are more common in diabetes mellitus and alcoholic arthropathy. After the evaluation of plain radiographs, a medullar MRI should be performed, since it is the most effective imaging modality to visualise the syrinx.^{6 7} Despite the central location of the syrinx, medullar involvement is usually asymmetrical in syringomyelia. According to a recent retrospective study of 12 patients with syringomyelic arthropathies, the side of the syrinx was identical to the side of the affected limb in all cases, which explains why neurological symptoms are asymmetrical in patients with syringomyelia. This finding was also retrieved in several previous reports.²

The pathogenesis of NA is not fully understood, and still remains a matter of debate. There are two main pathophysiological theories: the neurotraumatic theory and the neurovascular theory. According to the neurotraumatic theory, which was discovered by Volkman and Virchow, NA is caused by an accumulation of repetitive subclinical joint traumas that are unnoticed because of a lack of sensation in the affected joints. The loss of somatic muscle reflexes, which protect the joint from exceeding certain limits of motion, leads to joint destruction. According to the neurovascular theory, introduced by Mitchell and Charcot, NA is due to the damage to the central nervous system that controls joint and bone nutrition secondary to sympathetic dysfunction. The disruption of normal neurovascular reflexes leads to hyperaemia, activation of osteoclasts and massive bone resorption.^{1–5 7}

In the management of NA, treating the underlying neurological disorder is crucial to avoid disease progression.^{2 3 7} According to a previous publication that reviewed 169 cases with syringomyelic arthropathy, all patients who underwent surgical decompression achieved satisfactory outcomes without any signs of disease progression.² Given its rarity, joint surgery procedures (such as arthrodesis, arthroplasty and synovectomy) for the neuropathic wrist are not well documented in the literature. However, the literature review has shown that operative treatment for the arthropathic shoulder has unsatisfactory results, while conservative measures (immobilisation, splinting, bracing, joint fluid aspiration and physical therapy) have much better outcomes.^{3–5 7} In this report, posterior fossa decompression was indicated but refused by the patient. No other surgical procedure was planned, and the patient was advised to wear a splint cuff for her right wrist.

Learning points.

• Neuropathic arthropathy secondary to syringomyelia is a rare entity, poorly published in the literature, with a mysterious pathogenesis.

• The management of neuropathic arthropathy requires an early diagnosis of the underlying neurological disorder, which enables the treating physician to stop the progression of the disease.

• Immobilisation of the affected joint is the keystone of the treatment of neuropathic arthropathy since all surgical methods, which were previously reported, led to poor outcome.

Ethics statements

Patient consent for publication

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