FATAL DESTRUCTIVE CERVICAL SPONDYLOARTHROPATHY IN TWO PATIENTS ON LONG TERM DIALYSIS

Jeffrey C. Allard

Maria E. Artze

Guy Porter

G. O. Perez

L. Ghandur-Mnaymneh

R. deVelasc


                From the Departments of Radiology, Medicine, and

Pathology, University of Miami School of Medicine, and the

Veterans Affairs Medical Center, Miami, Florida.

Correspondence to JCA, PO Box 016960 ® 109), Miami, FL

33101, Tel. 305 549 7844


FATAL AZOTEMIC DESTRUCTIVE SPONDYLOARTHROPATHY; FINDINGS- -AND IMPLICATIONS

Abstract

Two patients with fatal cervical cord compressive

myelopathy are described, both of whom had been on

dialysis for over fifteen years. Destructive changes were

noted in mid and upper cervical regions, with soft tissue

mass in atlanto_occipital region in one patient. Clinical,

radiographic, and biopsy findings suggest both amyloid and

hyperparathyroidism as etiologies for these destructive

spinal changes. These cases emphasize the aggressive

potential of destructive spondyloarthropathy associated

with dialysis which has not been reported to date.


Introduction


                Erosive arthropathy in patients on chronic dialysis

was initially described in the hands. Because up to 30% of

patients had these findings and were asymptomatic, the

entity was initially felt to be "innocuous" [1]. Since

1980 the spectrum and severity of changes in renal

osteodystrophy has been expanded to include erosions in

the axial as well as the peripheral skeleton [2]. A

destructive spondyloarthropathy (DSA) associated with

dialysis was first described in 1984, with a total of 73

cases being reported to date [3-15]. Although

approximately 20% of ADS cases have had neurologic

compressive symptoms, there have been no cases of

paralysis or death attributed to the spinal lesions thus

far [2-15]. We report two cases of fatal cervical cord

compression related to ADS and discuss etiology and

clinical implications.

Case reports


Case one


A 51_year_old woman on maintenance hemodialysis for

17 years was admitted for neck pain and quadriparesis.

Imaging studies disclosed odontoid destruction with

associated mass which caused cervical cord compression as

well as peripheral arthropathy and other evidence of renal

osteodystrophy (Fig. 1). Surgical specimen revealed

fibrocartilage with degenerative change and synovial

hyperplasia with hemosiderin and fibrosis. No amyloid or

crystals were found, despite electron microscopy. Patient

expired two months later with evidence of progressive

neurologic deterioration

Previous history included multiple blood

transfusions, spontaneous rib fractures, hip and knee

joint replacement surgery, and carpal tunnel surgery.

Laboratory values included negative rheumatoid factor,

normal aluminum levels, and calcium, phosphorus, and

alkaline phosphatase levels which varied from normal to

elevated.


Case two


A 67 year old man on dialysis for 15 years was

admitted for neck pain and spastic paraplegia. Seven years

previously he had undergone anterior decompressive

diskectomy with fusion at C3-5 for spinal stenosis and

cervical root syndrome. Imaging studies at that time

demonstrated findings of DSA involving C3-4 and C5-6

levels (Fig.2a)

On this admission, MRI disclosed increased kyphosis

from C3 to C6 with spinal canal stenosis and cord atrophy

(Fig. 2b). Erosive arthropathy of hands with carpal cyst

formation was also present and noted to have progressed

from previous studies (Fig. 2c). Iliac crest bone biopsy

showed aluminum deposits and increased osteoclastic and

osteoblastic activity consistent with secondary

hyperparathyroidism. There was marked elevation of serum

parathormone, calcium, and phosphorus levels. Patient

expired prior to surgical decompression related to sepsis

from complicating decubitus ulcers.

Discussion

Although the frequency of spinal erosive changes

associated with dialysis is up to 25%, destructive changes

are less common [6]. The frequency of changes increases

with the duration of dialysis and a recent report also

indicates that dialysis is not required for the

development of DSA, but that duration of renal failure may

be the more important factor [4,13]. Most cases of DSA

with follow-up have demonstrated relatively rapid

progression of destructive changes over a period of months

[2-12]. Early radiologic findings include erosions of

anterosuperior or anteroinferior corners of vertebral

bodies which are similar to the Romanus lesion in

ankylosing spondylitis [6,9]. Osteophytes are absent.

Later changes include disk space narrowing with

associated end plate erosions and irregularity caused by

cystic erosions and end_plate sclerosis [4,8]. CT

scanning, as in our cases, best demonstrates the erosions

which are well defined and variably sized [5-8,14]. At

this stage differentiation from infection or neuropathic

change is difficult with plain films alone. Needle biopsy,

bone scan, and MRI have been used to exclude infection in

some cases [3,6-10]. Both of our cases had MRI and showed

no evidence of T2 prolongation to indicate inflammation or

infection, in agreement with other reported cases except for

one [9]. Erosions at multiple sites in the appropriate

clinical context, as in our cases, indicates that

infection is less likely [3-13]. In addition, the absence

of associated paravertebral swelling or soft tissue mass

has ruled against infection [6,8,10].

Most reported cases of DSA have involved the cervical

spine, and multilevel disease is common [4-14]. Mid¬cervical

disease is most frequent. Lumbar is more common

than thoracic spine involvement. Vertebral subluxation is

an increasingly recognized complication of DSA and is of

particular importance because of potential neurologic

complications. 13 cases of DSA in the literature have had

subluxations, particularly at the C3-4 level [5-8,10-13,15].

Of five reported instances of surgical

intervention, all cases had subluxation. Three cervical,

one thoracic, and one lumbar decompression have been

performed [5,10,11,13]. Three additional cases of cord

compression have been mentioned which did not require

surgery [5,14]. Spinal subluxations have also been noted

in dialysis patients independent from DSA, suggesting

possible ligamentous laxity in these patients [15].

A recent report has described pseudotumors of the

craniocervical junction on MRI, defined as retrodental

soft tissue wider than 5 mm, in 28% of a population on

dialysis for greater than 10 years [14]. Prior to this

report, only one other case of atlantoaxial involvement

had been reported which had unilateral narrowing [9]. Only

one of the pseudotumor patients had plain film findings.

In 5 of 7 pseudotumor patients, CT demonstrated bony

cystic erosions adjacent to the soft tissue mass [14]. The

absence of other rheumatoid features such as subluxation

was noted in all cases. Our case one is an advanced

example of pseudotumor formation with associated

horizontal atlanto_axial subluxation. As with

intervertebral imaging in DSA, our pseudotumor like others

reported was low to intermediated signal on T2-weighted

MRI. One should also appreciate that pathological and

radiologic changes at atlanto-axial level are likely to be

unique as this is a synovial joint.Many etiologic agents have been postulated in ADS,

including amyloid, crystal deposition, iron, and aluminum

[2_16]. Only biopsy specimens containing amyloid (beta 2

microglobulin){n=10}, hydroxyapatite {n=2}, and

pyrophosphate crystals {n=1} have been documented to date

[3_5,7,9,11,14]. We were able to demonstrate neither

crystals nor amyloid in our biopsy specimens. The

discovery of aluminum in one of our specimens is probably

not related to DSA Indeed, aluminum deposits are present

in up to half of all bone biopsy specimens in chronic

dialysis patients and are correlated only with the

presence of osteomalacia [2,17].

Although some initial reports suggested crystal

deposition as etiologic, recently reported cases have

failed to show these [2-13]. Generally, chondrocalcinosis

is probably no more frequent in dialysis patients than in

age_matched controls, which should also discredit the

crystal theory [4]

Recovery of beta 2 microglobulin, the specific

amyloid protein which is elevated in dialysis patients, is

more frequent. In several cases, however, recovery of

amyloid has been distant to the site of DSA, particularly

in the cases with carpal tunnel syndrome [4,14].

Peripheral juxtarticular cystic changes have also been

demonstrated to contain amyloid, particularly when located

in the carpal bones or heads of humerus or femur [16].

Some authors have used this association as collaborative

evidence for an amyloid etiology in DSA [5,9,14,15]. That

one of our cases had carpal tunnel surgery and both had

carpal cysts is our only evidence for an amyloid etiology.

Although discal, synovial, and perivertebral accumulations

of amyloid have been found, it is still unclear as to how

this results in DSA [2,3,5].

Severe hyperparathyroidism has been noted in

approximately 80% of DSA patients, many of whom underwent

parathyroidectomy [3-5,12-14]. In at least three patients

with DSA, surgical parathyroidectomy resulted in dramatic

symptom relief, and a stabilization of radiographic

findings [12]. Peripheral erosive arthropathy has correlated

poorly with hyperparathyroidism in most cases

and correlated variably with DSA [2-7,9]. Correlation of

subperiosteal erosions and rugger_jersey spine has not

been studied frequently enough to make conclusions. Both

of our patients had biochemical evidence of secondary

hyperparathyroidism. In addition, case one had central

osteosclerosis and case two had biopsy evidence to support

this as an etiology. Although parathormone might cause

bony resorption with associated ligamentous weakening, the

exact mechanism of DSA production remains speculative, and

perhaps is multifactorial.

In summary, DSA is an increasingly recognized

and sometimes lethal process associated with long standing

renal failure usually in conjunction with dialysis.

Radiographically, the presence of disk space narrowing

with irregular end plate destruction resembles infection

and biopsy may be needed to exclude this diagnosis when it

is clinically suspected. Pseudotumor formation in

atlantoaxial region, with bony erosion, is a second

manifestation of ADS. As ADS is most frequent and

potentially lethal in the cervical region, we recommend

lateral radiographs and perhaps MRI of this region

especially if the patient is symptomatic, or has been on

hemodialysis for more than five years

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Figure legends

_1a. Sagittal SE 1800/60 one year prior to admission shows

pseudotumor (white arrows) surrounding odontoid and

narrowing spinal canal.

1b. Post myelography CT at same time shows multiple cystic

erosions of odontoid and C2 with large retrodental soft

tissue mass which impinges on anterior subarachnoid space.

These changes progressed on studies one year later

resulting in cord compression

1c. Advanced erosive arthropathy of hands involving both

distal and proximal portions. Cortical tunneling indicates

secondary hyperparathyroidism.

1d. Central osteosclerosis, healed right rib fractures,

and advanced erosions of left humeral head shown1e. Marked joint space narrowing with irregular erosion of

medial tibial plateau led to joint replacement.

1f. Lateral operative view confirms needle placement in

region of pseudotumor. There is significant anterior

atlanto_axial subluxation.

2a. Lateral cervical view 7 years prior to admission shows

disk space narrowing at C3-4 and C5-6 with end plate

erosions, irregularity, and sclerosis which is

characteristic for DSA.

2b. CT at same time at C5 level shows cystic erosions in vertebral body and lateral mass much better than plain

film.

2c. SE 600/20 sagittal MR at time of admission shows

cervical malalignment with kyphosis and cord compression

with atrophy from C3 to C6. Note metallic artifact

anteriorly at C5-6 level related to previous surgery.

2d. Hands demonstrate cortical tunneling, juxtarticular

erosions, and carpal cysts.