tropic virus type I11 from the central nervous system. Ann Neurol 1986;20:362-364

14. Navia BA, Jordan BD, Price RW. The AIDS dementia com- plex: I. Clinical features. Ann Neurol 1986;19:517-524

15. Navia BA, Cho E-S, Petito CK, Price RW. The AIDS dementia complex: 11. Neuropathology. Ann Neurol 1986;19:525-535

16. de la Monte SM, Ho DD, Schooley RT, et al. Subacute enceph- alomyelitis of AIDS and its relation to HTLV-111 infection. Neurology 1987;37:562-569

Atlantoaxial Subluxation in Psoriatic Arthropathy Jerry G. Kaplan, MD,* Richard S. Rosenberg, MD,* Trevor DeSouza, MD,” Kalmon D. Post, MD,§ Mark D. Freilich, MD,t Oscar Salamon, MD,? George Iantos, MD,t and Elizabeth Reinitz, MDS

Symptomatic adantoaxial dislocation occurs rarely in psoriatic arthropathy and has previously been reported only as a late complication in this disorder. We report severe upward axial dislocation and acquired basilar im- pression as a presenting manifestation of psoriatic ar- thropathy. Magnetic resonance imaging is useful in evaluating this condition.

Kaplan JG, Rosenberg RS, DeSouza T, Post KD, Freilich MD, Salamon 0, Lantos G, Reinitz E.

Atlantoaxial subluxation in psoriatic arthropathy. Ann Neurol 1988;23:522-524

Atlantoaxial (AA) dislocation is a well-recognized complication of psoriatic arthropathy (PA). Excessive anterior displacement of the axis has been demon- strated in as many as 45% of patients with PA but is rarely of clinical significance El]. Upward axial dis- placement, accompanied by basilar impression, is a rare and dangerous complication and may compromise the medulla or vertebral arteries 121. Severe AA dislo- cation has previously been associated only with severe widespread arthropathy in psoriatics. We report up- ward axial dislocation and basilar impression as the presenting manifestation of PA, emphasizing the role of magnetic resonance imaging (MRI) in diagnosis.

Case Report A 40-year-old woman presented with severe pain at the back of the neck of three years’ duration. During this period she consulted several different specialists, and the diagnosis of temporomandibular joint arthritis was eventually made. Be- fore undergoing surgery of the temporomandibular joint, she sought a rheumatological opinion from one of us (E. R.). The pain was progressive and was accompanied by limitation of neck movement and a feeling of coldness and tingling in the occipital region. Excessive neck movement caused epi- sodes of quadriparesis or left hemiparesis with facial sparing that lasted up to a few hours. During the later stages of her illness, the patient developed a left head tilt. There was a six- year history of mild psoriasis confined to fingers and nails without joint pain, swelling, or limitation of movement.

Physical examination revealed psoriasis confined to the terminal digits and nails, mild head tilt to the left, and severe nuchal rigidity in all directions. No forceful attempt was made to move the neck. On neurological examination, dif- fuse hyperreflexia accompanied equivocal Babinski’s signs. Electromyography, nerve conduction studies, latex fixation, rheumatoid factor, antinuclear antibodies, complete blood count, and radiographs of the hands, lumbar spine, and sa- croiliac (SI) joints were normal. N o evidence of human leukocyte antigen (HLA) €327 was found. Cervical spine films showed subluxation of C1 over C2 with upward hernia- tion of the odontoid Up beyond the foramen magnum. Com- puted tomography (Figs 1, 2) showed superior, anterior, and lateral subluxation of the dens. Sagittal MRI (Fig 3) demon- strated a small mass above the dens with brainstem compres-

~ ~

From the Departments of *Neurology, ?Radiology, and $Medicine, Albert Einstein College of Medicine, Bronx, NY, and the $Depart- ment of Neurosurgery, Columbia University College of Physicians and Surgeons, New York, NY. Received Sep 9, 1987, and in revised form Nov 2. Accepted for publication Nov 6, 1987. Address correspondence to Dr Kaplan, Department of Neurology, Albert Einstein College of Medicine, 1300 Morris park Avenue, Bronx, NY 10461.

Fig 1 . Axial computed tomography scan showing odontoid tip invaginated into and eccentric within foramen magnum. There is anterior, superior, and lateral subluxation of C-1 arch in re- lation to c - 2 with rotational component. Hypertrophic changes (arrowhead) are seen adjacent to tip of clieus on left.

522 Copyright 0 1988 by the American Neurological Association

Pig 2. Sagittal reconstruction of computed tomography of skull base, demonstrating cranial settling. Note the odontoid tip 17 mm above Chamberlain’s line (line of black arrows) and several millimeters above the clivus.

sion by the dens. The lower cervical spine appeared normal on all examinations.

Suboccipital craniectomy, with resection of the posterior arch of C-1 and fusion of the occiput to C-2, disclosed thick- ened connective tissue (pseudonunor) in the suboccipital and C-1 areas. The surgical procedure relieved all symptoms and the patient returned to work. PA involving several distal interphalarlgeal joints and skin lesions has subsequently worsened, requiring low-dose methotrexate therapy.

Discussion Psoriatic arthropathy is a chronic inflammatory ar- thritis. In many patients with psoriasis, nail involve- ment is accompanied by destruction of distal inter- phalangeal joints. Spondyloarthropathy affecting the SI joints or spine occurs in approximately 20% of cases and may antedate skin, nail, and peripheral joint in- volvement (31. This spondyloarthropathy can be dif- ferentiated from ankylosing spondylitis (AS), as SI joint involvement in PA is often asymmetrical and is accompanied by paravertebral ossifications and verte- bral and disc calcification, whereas AS often leads to symmetrical SI joint involvement and a characteristic “bamboo” spine [43. The incidence of HLA B27 is elevated in both disorders, more in AS than PA (31. PA may present as a symmetrical seronegative polyar- thritis that may superficially resemble rheumatoid ar- thritis, a more common cause of AA subluxation, or may present as a monoarthropathy or asymmetrical oligoarthropathy (51.

Patients with PA are predisposed to AA subluxa- tion. The transverse (cruciate) Ugament of the dens is essential for AA joint stability. When this hgament is rendered lax and incompetent by chronic synovitis, the nearly horizontal articular facets of C-1 and. C-2 do little to stabilize the AA joint [b, 73. Consequently, there may be forward or latera! slippage of the atlas with neurological or vascular compromise or both. Ex-

Pig 3. Sagittal magnetic resonance image (spin echo pulse se- quence, TR = 500 msec and TE = 32 msec) demonstrating kinking of cewicomedullary junction. Owing to the eccentric posi- tion of the odontoidprocess in relation to the base of the cranium, the superior aspect of the dens could not be delineated even on sequential scans. An imgular soft-tissue mass (arrow) is seen around the posterior aspect ofthe odontoid process.

cessive anterior displacement of more than 3 mm oc- curs with varying frequency (up to 45%) and is gener- ally asymptomatic (11. Upward displacement of the axis is relatively uncommon. When severe, it is associ- ated with acquired basilar impression, which occurs as the spine is shifted upward relative to the skull, re- sulting in an upturning of the foramen magnum mar- gins E8}. This may compress the spinal cord, brainstem, or vertebral arteries; upward displacement is more dangerous than horizontal movement (93. Subaxial subluxation of the midcervical spine may also occur, resulting in paraplegia and death from spinal cord com- pression (101. In all previously reported cases, AA subluxation occurred late in the course of PA, and was heralded by advanced arthropathy generally involving the spine. Our patient was unique because she devel- oped AA dislocation several years before developing peripheral arthritis. Severe upward dislocation of the axis with acquired basilar impression and kinking of the cervicomedullary junction were present when skin and nail lesions of psoriasis were mild. There was no clinical or radiographical evidence of digital arthritis or SI joint or subaxial spinal involvement.

MRI is an effective means of evaluating the cranio-

Brief Communication: Kaplan et al: Psoriatic Arthropathy 523

cervical junction El 11. It provides a direct, noninvasive demonstration of bony subluxation and distortion of the spinal cord and brainstem. Our experience sug- gests that MRI is helpful in screening for AA dislo- cation in patients with PA and other spondyloar- thropathies. In centers where MRI is unavailable, computed tomographic myelography can be utilized E12J

The operation for severe AA dislocation is usually posterior fusion, the approach used for our patient. Transoral odontoidectomy has recently been used and has the advantage of early mobilization 112).

We conclude that AA subluxation and basilar in- vagination may occur as a monoarthropathy early in the course of PA, predating the onset of systemic ar- thritis, and that MRI should be used when the condi- tion is suspected.

References 1. Killebrew K, Gold RH, Skolkoff SD. Psoriatic spondylitis.

Radiology 1973;708:9-16 2. Peterson CC Jr, Silbiger ML. Reiter's syndrome and psoriatic

arthritis: their roentgen spectra and some interesting similarities. Am J Roentgenol Radium Ther Nucl Med 1967;101:860-871

3. Arnett FC. Psoriatic arthritis: relationship to other spondyloar- thropathies. In: Gerber LH, Espinota LR, eds. Psoriatic ar- thritis. Orlando: Grune & Stratton, 198595-108

4. Resnick D. Hyperostosis and ossification of the cervical spine. Arthritis Rheum 1984;2 7: 5 64-5 69

5. McCormack GD, Barth W. Classification and diagnosis of psoriatic arthritis. Orlando: Grune & Stratton, 1985:59-82

6. Resnick D, Niwayama G. Physical injury. In: Resnick D, Niwayama G, eds. Diagnosis of bone and joint disorders. Phila- delphia: Saunders, 1981 :2292-2296

7. Yeadon C, Dumas JM, Karsh J. Lateral subluxation of the cervi- cal spine in psoriatic arthritis: a proposal mechanism. Arthritis Rheum 1984;27:564-569

8. Martel W. The occipito-atlanto-axial joints in rhematoid arthritis and ankylosing spondylitis. Am J Roentgenol Radium Ther Nucl Med 1961;86:223-240

9. Little H, Swinson DR, Cruickshank B. Upward subluxation of the axis in ankylosing spondylitis. Am J Med 1976;60:279-285

10. Fam AG, Cruickshank B. Subaxial cervical subluxation and cord compression in psoriatic spondylitis. Arthritis Rheum

11. Sze G, Brant-Zawadzki MN, Wilson CR, et al. Pseudotumor of the cranio-vertebral junction associated with chronic subluxa- tion. MR imaging studies. Radiology 1986;161:391-394

12. Stevens JM, Kendall EB, Crockard HA. The spinal cord in rheumatoid arthritis with clinical myelopathy: a computed my- elographic study. J Neurol Neurosurg Psychiatry 1986;49: 140- 155

1982;25:101-106

Motor Neuron Syndrome and Monoclonal IgM with Antibody Activity Against Ganghosides GM 1 and GDlb Ettore Nardelli, MD,' Andreas J. Steck, MD," Thomas Barkas, PhD,* Myriam Schluep, MD,* and Felix Jerusalem, MDt

~~~ ~

We demonstrated that an IgM M-protein from a patient with motor neuron syndrome had antibody activity against gangliosides GM1, GDlb, and asialo GM1. Stud- ies with a sugar-binding lectin suggested that the epi- tope in the patient's M-IgM involved the Gal(p1-3) GalNAc moiety. Immunohistological techniques dem- onstrated staining of axons in the lumbar roots, granular cells, and white matter in the cerebellum by the pa- tient's M-IgM. We propose that, in this case, an autoim- mune mechanism of motor neuron syndrome associated with a monoclonal protein is most likely.

Nardelli E, Steck AJ, Barkas T, Schluep M, Jerusalem F. Motor neuron syndrome and

monoclonal IgM with antibody activity against gangliosides GM1 and GDlb.

Ann Neurol 1988;23:524-528

Attention has been directed toward a possible relation- ship between monoclonal protein (M-protein) and neoplasia with motor ' neuron disease. The patho- genesis of motor neuron disease is still obscure, but an association with serum M-protein El-31 has been found. We report a patient with a motor neuron syn- drome and an IgM M-protein with autoantibody activ- ity against gangliosides GM1, GDlb, and asialo GM1.

Case Report A 64-year-old woman developed progressive generalized muscle weakness and wasting 2 years prior to admission. She had undergone mastectomy for breast cancer 15 years ago. The general physical examination revealed no abnormalities. On neurological examination, muscle atrophy and fascicula- tions in all limbs were evident. Muscle weakness was sym- metrical and more marked proximally; trunk muscles were also affected but there was no involvement of bulbar mus- cles. Tendon reflexes were decreased, and a Babinski's sign was equivocal on the left side. Sensation was normal.

From the *Department of Neurology, Centre Hospitalier Univer- sitaire Vaudois, Lausanne, Switzerland, and the "Department of Neurology, University of Bonn, Bonn, West Germany. Received Jul 10, 1987, and in revised form Oct 16. Accepted for publication Nov 17, 1987. Address correspondence to Dr Steck, Department of Neurology, CHUV, 1011 Lausanne, Switzerland.

524 Copyright 0 1988 by the American Neurological Association