Primary lateral sclerosis

ABSTRACT

Multiple sclerosis (MS) is a neurological disease that occurs in 5 to 100 per 100,000 people. Thus, it is reasonable that, as doctors of chiropractic become increasingly recognized as primary-contact neuromusculoskeletal specialists, most will encounter undiagnosed MS at some point in their careers. In these cases, the doctor of chiropractic will be responsible for making, or at least suspecting, the diagnosis and coordinating the appropriate referral. Reported here is an unusual case of a woman who was referred to a chiropractic spine center with the sole complaint of foot drop, which was ultimately attributed to MS.

Key words: multiple sclerosis, neurology, foot drop, chiropractic

INTRODUCTION

Multiple sclerosis (MS) is defined as "a chronic disease of the central nervous system (CNS), characterized by discrete areas of demyelination and axonal injury associated with inflammatory activity."1 Its prevalence varies from less than 5 per 100,000 to 100 per 100,000, depending on the geographic region. The incidence of MS is distributed geographically; high-risk areas include northern and central Europe (except Scandinavia), Italy, the northern United States, Canada, southeastern Australia, parts of the former Soviet Union, and New Zealand. Medium-risk areas include southern Europe (except Italy), the southern United States, northern Australia, parts of the former Soviet Union, and South Africa (white population only).1 The geographical distribution of MS is attributed to both genetic and environmental influences.2,3 Environmental influences show a trend for an increase in the prevalence with increased latitude.1 There have been several studies reported in which immigrants that migrate have developed a prevalence rate similar to the indigenous population.4,5 Specifically, people who migrate from an area of high incidence to one of low incidence before the age of 15 take on a similar incidence to those native to the area to which they migrated. This, among other lines of evidence, has led some to attribute an etiologic role to childhood infection.6 A genetic link has been shown because of the consistently low rate of certain racial groups such as African American, east Asians, Sami, Inuit, native Americans, Saudis, and Maoris.1 all these data suggest that the susceptibility of the disease is genetically determined and the onset is triggered by an environmental factor.1

The overall prevalence of MS is twice as high in women as in men.2 The mean age of onset is around 30 years, and the peak age of onset is 23 to 24 years.1 Approximately 70% of cases arise between 20 and 40 years of age.1

MS lesions are characterized by discrete areas of demyelination and axon injury in the CNS. The lesions can occur anywhere in the brain or spinal cord, but are most commonly found in specific areas of white matter.1 The most commonly affected areas are tissues bordering the lateral and fourth ventricles, periaqueductal tissue, the corpus callosum, the optic nerves, chiasma and tracts, the corticomedullary junction, and the subpial section of the brainstem.1 The most common areas of the spinal cord are the anterior columns flanking the median fissure, centrally in the dorsal columns, and subpialIy. There seems to be a tendency for lesions to develop in white matter adjacent to cerebrospinal fluid.1 The pathogenesis is mostly hypothetical; all that is known for certain about MS is that the demyelination and axon damage that is characteristic of the disease occur in the presence of immune cells and elevated levels of their products.1 It is thought that this represents an autoimmune process that leads to an inflammatory response, which results in destruction of the myelin sheath and, ultimately, axonal degeneration. Specifically, it is believed that T cells in the periphery that are specific for myelin protein are activated as a result of interaction with a virus, another infective agent, or some other environmental stimulus. The activated T cells migrate across the blood-brain barrier and enter the CNS. Once inside the CNS, activated T cells secrete immune mediators such as cytokines and chemokines, initiating an inflammatory cascade that leads to the death of oligodendrocytes, the destruction of the myelin sheath, and the degeneration of axons.1

Axon damage is thought to be the cause of the permanent neurologic disability characteristic of MS. It is thought that axon damage occurs early in the disease process, but is not evident until later stages due to the nervous system's ability to compensate for the axon damage until the damage reaches a threshold.' The understanding of early axon damage is important to derive a treatment strategy that will limit the amount of damage early in the course of the disease.1

Presented here is a case of a woman whose only presenting complaint was weakness in the lower extremity, but whose examination findings led to a diagnostic process that concluded with a diagnosis of multiple sclerosis.

CASE REPORT

The patient was a 52-year-old crossing guard who was referred by her internist with a complaint of weakness of the right lower extremity, which had started eight months previously. She first noticed it when walking. She found that her right foot would start to "drag" about 40 minutes into her walk. Over time, the weakness became progressively more pronounced and occurred ear lier in the walk, until it would start after approximately 20 minutes. She stated that she had some "soreness" in the right lumbosacral area, but no significant lower-back pain. She denied motor loss, as well as bowel or bladder difficulties, abdominal pain, or lower-extremity swelling, coldness, or discoloration related to the weakness. She did not experience weakness during any other activities.

Past medical history was remarkable for asthma, for which she took Albuterol. Review of systems was remarkable for hot flashes, some increase in urinary frequency of recent onset, and occasional anxiety and depression. She was married with two children. She did not smoke, drank two glasses of wine per night, and walked for exercise. Family history was unremarkable.

Examination revealed a well-nourished, pleasant woman who appeared to be in no acute distress. Blood pressure was 125/80 on the left. Temperature was 98.7 degrees Fahrenheit. Pulse was 72 per minute. Respirations were 16 per minute.

The straight-leg raise and well-leg raise were negative. Heel and toe walking were within normal limits, but she had difficulty with tandem walking. Romberg's position was held with eyes closed without difficulty. Examination of cranial nerves II through XII was within normal limits. Pupils were equal and round and reacted to light and accommodation. Funduscopic examination was unremarkable. Sensory examination to pin in the upper and lower extremities was unremarkable. Vibration sense was absent bilaterally in the feet and reduced bilaterally in the hands. Motor strength was 5/5 bilaterally throughout, with the exception of the right tibialis anterior and extensor hallucis longus, which were both 4+/5. Muscle stretch reflexes were 3+ and symmetric throughout. Plantar responses were upgoing bilaterally. Tromner's signs were present bilaterally. Scapulohumeral reflexes were present bilaterally. Jaw jerk was normal. There were 4 or 5 beats of clonus in the ankles bilaterally. Spasticity was noted in the lower extremities upon rapid knee flexion bilaterally. No clonus was noted in the upper extremities. There was no evidence of pronator drift.

Because of the upper motor neuron findings present on exam, which were localized to below the brainstem, a cervical MRI was ordered, with the suspicion of cervical spondylotic myelopathy, or some other cervical myelopathic process.

The MRI revealed a sharp kyphosis in the mid-cervical spine with spondylosis at C4-5 and disc bulge at C5-6, both of which encroached on the spinal cord. There was mild cord atrophy at the C4-5 level, and hyperintensity could be seen on the T2 weighted images (Fig. 1). These findings were suggestive of cervical spondylotic myelopathy, except that the hyperintensity within the spinal cord was in the posterior aspect of the cord, rather than in the anterior, which was the site of compression on the cord. Because hyperintensity in the posterior cord is a characteristic finding in MS, a brain MRI was ordered. This demonstrated multiple small, circumscribed, deep white matter subependymal T2 hyperintensities, characteristic of multiple sclerosis. The diagnosis was confirmed with lumbar puncture. She was referred to a medical neurologist and was started on Interferon self-injection therapy. There was nothing in her clinical picture that caused the treating clinician to feel that chiropractic co-management would be contributory.

DISCUSSION

Four forms of MS have been delineated, based on the clinical course. These are relapsing/remitting, second-ary progressive, primary progressive, and progressive relapsing.7 The relapsing-remitting form is the most common, occurring in 80 to 85% of cases, and is characterized by episodes of neurologic impairment, with periods of complete or partial recovery between episodes. Some patients with this form eventually develop the secondary progressive form, in which neurologic impairment progresses continuously. With the progressive form, a gradual progressive development of the clinical course occurs without relapses and remissions.8

MS can be a difficult diagnosis to make. The presenting complaint(s) can be varied and can encompass virtually any part of the nervous system. In general, MS should be suspected when a patient presents with neurologic symptoms and dysfunction involving different areas of the nervous system. This differentiates a widespread nervous system disease like MS from a more localized neurological disorder. As demonstrated in this case, however, there may only be localized symptoms early in the process.

The most common initial symptoms of MS include sensory disturbances, unilateral optic neuritis, diplopia, limb weakness, clumsiness, gait ataxia, and neurogenic bladder and bowel symptoms.6 Cortical impairment, including aphasia, apraxia, recurrent seizures, visual field loss, early dementia, and extrapyramidal phenomena (chorea and rigidity) are also observed, but occur much less frequently. Later in the disease process, there may be cognitive impairment, depression, emotional lability, dysarthria, dysphagia, vertigo, progressive quadriparesis and sensory loss, ataxic tremors, pain sexual dysfunction, spasticity, and other manifestations of CNS dysfunction.6·9

The neurologic examination findings depend on the parts of the nervous system that are affected. Upper motor neuron signs are common. Also, Lhermitte's sign is often seen, in which cervical flexion causes an "electric" feeling down the back. In addition, the Uthoff phenomenon may be present, in which clinical signs or symptoms worsen with increased temperature or after exercise.10

Diagnostic tests for MS include MRI, lumbar puncture (LP) for the analysis of CSF, and visually evoked potentials (VEP). Each of these tests has limitations in sensitivity and specificity. MRI is thought to be the most sensitive and specific in making a diagnosis of MS. The following are the imaging criteria for brain abnormality according to the International Panel on MS Diagnosis:6

There must be three of four of the following:

1. One gadolinium-enhanced lesion, or nine T2 hyper-intense lesions if there is no gadolinium-enhancing lesion

2. at least one infratentorial lesion

3. at least one juxtacortical lesion

4. at least three periventricular lesions.

LP adds information about inflammation and immunological disturbances; it is useful when the clinical picture is unusual, or when imaging criteria for diagnosis are not fulfilled.6 LP typically reveals the presence of oligoclonal IgG bands that are different from any such bands in serum and/or the presence of an elevated IgG index.11 Also, the levels of lymphocytic pleocytosis are typically less than 50/mm.3,6 VEP can be used to provide a supplemental objective form of evidence. Correct interpretation of VEP is essential.6 In spite of advances in diagnostic testing, however, MS is still considered primarily a clinical diagnosis, as clinical findings are essential in distinguishing a clinically isolated syndrome from ongoing disease activity.12

The most important differential diagnoses in patients with MS are acute disseminated encephalomyelitis, Bechet's disease, sarcoidosis, brucellosis, Lyme disease, adrenoleukodystrophy, opportunistic infections secondary to HIV, mitochondrial encephalopathy, transverse myelitis, cervical spondylotic myelopathy (as with the case presented here), tropical spastic paraplegia, and vitamin B12 deficiency.9

At this point, no treatment has been demonstrated to be highly effective, but several disease-modifying methods have been developed. Interferon-[beta] is the drug of choice. This is an antagonist to interferon-[gamma] and inhibits some T cells. It has been demonstrated to reduce the frequency of relapse, although its long-term effects on progression are not clear. Glatiramer acetate (Copacone(TM)) is also used. Intravenous immunoglobulin has been reported to facilitate remyelination and produce clinical improvement in the relapsing-remitting form. With regard to symptom management, steroid therapy is often useful during relapses.13

The case reported here was interesting in that the only presenting complaint was unilateral weakness in the lower extremity with walking. This is not typical of MS, but as the disease process was in its early stage, this was the only symptom that the patient was experiencing. It was also interesting in that the examination findings were suspicious for cervical myelopathy. Upgoing toes on plantar response was seen on routine neurologic examination of the lower extremities. This prompted the examining doctor of chiropractic to move up in the central nervous system to attempt to localize the lesion. Tromner's reflexes were present, bringing the lesion to at least the C5 level. The scapulohumeral reflex14 was present bilaterally, bringing the lesion to between C5 and the brainstem. The jaw jerk reflex was normal, bringing the lesion to below the brainstem. Had this reflex been positive, it is likely that brain MRI would have been the imaging modality of choice. There was no sensory deficit, so no sensory level could be established, which also would have helped localize the lesion further.

CONCLUSION

A case was reported of a patient with atypical presentation of MS. This case illustrates the importance of performing an adequate examination on every patient, as the symptoms of which the patient complained were not strongly suggestive of MS. Clinical examination raised the suspicion of cervical myelopathy initially, but cervical MRI changed this suspicion to MS. Confirmation was established by brain MRI and LP.

References

1. O'Connor P. Key issues in the diagnosis and treatment of multiple sclerosis. Neurology 59 (suppl 3) 2002: S1-S33.

2. Ebers GC, Sadovinick AD. Epidemiology. In: Paty DW, Ebers GC, eds. Multiple Sclerosis. Philadelphia: FA Davis, 1997: 5-28.

3. Pryse-Phillips W, Costello F. The epidemiology of multiple sclerosis. In: Cook SD, ed. Handbook of Multiple Sclerosis. 3rd ed. New York: Marcel Dekker, 2001: 111:15-31.

4. Dean G. Annual incidence, prevalence and mortality of MS in white South African-born and in white immigrants to South Africa. BMJ 1967;2:724-730.

5. Gale CR. Migrant studies in multiple sclerosis. Prog Neurobiol 1995;47:425-448.

6. Hanson LJ, Cafruny WA. Current concepts in multiple sclerosis: Part I. South Dakota JMed. 2002;55(10):433-6.

7. Lublin FD, Reingold SC. Denning the clinical course of multiple sclerosis: results of an international survey. Neurology 1996; 46: 907-911.

8. McDonald WI, Compston A, Edan G, et al. Recommended diagnostic criteria for multiple sclerosis: guidelines from the international panel on the diagnosis of multiple sclerosis. Ann Neurology 2001;50:121-127.

9. Brinar W. The differential diagnosis of multiple sclerosis. Clin Neurol Neurosurg. 2002;104(3):211-220.

10. Zadat 00, Lerner AJ. The Little Black Book of Neurology. 4th Wolinsky JS, PROMiSe Study Group. The diagnosis of primary progressive multiple sclerosis.

11. Wolinsky JS, PROMiSe Study Group. The diagnosis of primary progressive multiple sclerosis. J Neurol Sciences. 2003;206(2):145-152.

12. Simon JH, Thompson AJ. Is multiple sclerosis still a clinical diagnosis? Neurology. 2003;61:596-597.

13. Hanson LJ, Cafruny WA. Current concepts in multiple sclerosis: Part II. South Dakota J Med. 2002; 55(11):477-481.

14. Shimizu T, Shimada H, Shirakura K. Scapulohumeral reflex (Shimizu): its clinical significance and testing maneuver. Spine 1993; 18:2182-2190.

Donald R. Murphy, DC, DACAN*#

David S. Williams, DC

* Clinical Director, Rhode Island Spine Center

# Clinical Teaching Associate, Department of Community Health, Brown University School of Medicine

Address all correspondence to:

Donald R. Murphy, DC, DACAN

Rhode Island Spine Center

600 Pawtucket Ave.

Pawtucket, RI 02860

Phone 401-728-2200

Fax 401-728-2031

rispine@aol.com

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