|Year : 2016 | Volume
| Issue : 1 | Page : 41-46
Magnetic Resonance Imaging of multiple sclerosis: A rare but real disease entity in Africans
Muhammad Zaria Ibrahim1, Abdulkadir Musa Tabari2, Joseph Bako Igashi1, Turaki Tahir Mohammed3, Sani Atta Abubakar3, Reginald Onyeadumarakwe Obiako3
1 Department of Radiology, Ahmadu Bello University/Ahmadu Bello University Teaching Hospital, Zaria, Nigeria
2 Department of Radiology, Bayero University/Aminu Kano Teaching Hospital, Kano, Nigeria
3 Department of Internal Medicine, Ahmadu Bello University/Ahmadu Bello University Teaching Hospital, Zaria, Nigeria
|Date of Web Publication||28-Jul-2016|
Dr. Muhammad Zaria Ibrahim
Department of Radiology, Ahmadu Bello University/Ahmadu Bello University Teaching Hospital, Zaria
Source of Support: None, Conflict of Interest: None
Background: Multiple sclerosis (MS) is the most common inflammatory demyelinating disease of the central nervous system in young and middle-aged adults; it also affects older people. There is an important role for magnetic resonance imaging (MRI) in the diagnosis of MS since an MRI can show multiple lesions, some of which can be clinically occult and MRI can show new lesions on follow-up scans. This is aimed to create awareness on the existence of MS in our environment and the role of MRI in the diagnosis of MS.
Patients and Methods: Five cases (three females and two males) of MS referred from the medical outpatient clinic and medical ward were seen in the MRI suite at the Department of Radiology, Ahmadu Bello University Teaching Hospital Zaria, Nigeria in the year 2014 whose diagnoses were missed on computed tomography (CT) but clinched on MRI were reviewed. The findings on MRI were correlated with clinical presentation.
Results: Titubation and amnesia were the most common mode of clinical presentation in the patients examined. Typical MS lesions involving the corpus callosum, U-fibers, temporal lobes, brainstem, cerebellum, and spinal cord were best depicted on MRI while CT scan did not show any evidence of such lesions.
Conclusion: MRI is the imaging modality of choice in the diagnosis of MS. Patients with typical symptoms in Africa should be subjected to MR examination in order to exclude MS.
Keywords: Africans, magnetic resonance imaging (MRI), multiple sclerosis (MS)
|How to cite this article:|
Ibrahim MZ, Tabari AM, Igashi JB, Mohammed TT, Abubakar SA, Obiako RO. Magnetic Resonance Imaging of multiple sclerosis: A rare but real disease entity in Africans. Arch Int Surg 2016;6:41-6
|How to cite this URL:|
Ibrahim MZ, Tabari AM, Igashi JB, Mohammed TT, Abubakar SA, Obiako RO. Magnetic Resonance Imaging of multiple sclerosis: A rare but real disease entity in Africans. Arch Int Surg [serial online] 2016 [cited 2021 Dec 3];6:41-6. Available from: https://www.archintsurg.org/text.asp?2016/6/1/41/187199
| Introduction|| |
Multiple sclerosis (MS) is the most common inflammatory demyelinating disease of the central nervous system in young and middle-aged adults; it also affects older people with a prevalence of 4/100,000 in South America and sub-Saharan Africa. In Nigeria, the reported hospital incidence of MS was 1.26 per 1,000 (5/3960) and the female to male ratio was 3:1.
Magnetic resonance imaging (MRI) has been shown to be the imaging modality of choice in the diagnosis and follow-up of patients with MS. Lesions are usually not visible on computed tomography (CT) scan while on MRI, the sensitivity and specificity of the lesions' detection reaches 80% and 90%, respectively.
There is an important role of MRI in the diagnosis of MS since MRI can show multiple lesions (dissemination in space), some of which can be clinically occult and MRI can show new lesions on follow-up scans (dissemination in time).
Different white matter diseases can mimic MS on MRI; however, there are peculiar features that are reserved for MS. According to the McDonald criteria for MS, the diagnosis requires objective evidence of lesions disseminated in time and space.
In view of the recent proliferation of MRI service facilities and paucity of reported cases of MS in Nigeria, the cases presented in this report are meant to create awareness on the existence of MS in our environment and advocate the role MRI in it diagnosis.
| Patients and Methods|| |
These five patients (three females and two males) with clinical and radiologic features of MS were referred from the medical outpatient clinic and medical ward were seen in the MRI suite (Siemens 0.2 T open low-field unit (Magnetom Concerto) USA 2005 MODEL) at the department of Radiology, Ahmadu Bello University Teaching Hospital Zaria, Nigeria in the year 2014 whose diagnoses were missed initially on CT scan but confirmed on MRI were reviewed. Findings on MRI were correlated with clinical presentations. All patients had the following MRI Protocols: T1W sagittal, axial pre- and postcontrast T1W postcontrast coronal, T2W axial, and T2W axial Fluid-Attenuated Inversion Recovery (FLAIR).
AK was a 36-year-old lady from Katsina State of Nigeria. She presented with a 12-year history of amnesia, right-sided hemiparesis, and progressive weight loss. Her disease started with severe vomiting followed by weakness of all limbs; she was not able to speak, eat, and move, and was fed via a nasogastric tube. However, her vision was normal. She regained power in all her limbs and was able speak and eat after 3 weeks. Subsequently, she developed behavioral and cognitive changes; the onset was chronic and gradually progressive. There was no premorbid history of any neurological deficit.
On examination, she was found to be conscious, restless, and wasted [body mass index (BMI) <12 kg/m 2]. Other laboratory investigations showed normal findings. Human immunodeficiency virus (HIV) status was negative. Cerebrospinal fluid (CSF) findings showed increased immunoglobin G (IgG) index and three oligoclonal bands.
MRI findings on axial FLAIR revealed bilateral hyperintense periventricular lesions of the same patient with normal CT scan in [Figure 1].
|Figure 1: Showing an axial brain Computed Tomographic (CT) Scan at the lateral ventricular body in a patient with MS, showed normal findings (no MS lesions seen)|
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She visited the UK where the diagnosis of MS was upheld and she was started on Tysabri (natalizumab) injection once every month, a drug for the treatment of relapsing MS. She is doing very well now.
AM was a 65-year-old housewife who presented with a longstanding history of titubation (>20 years) that had been progressively getting worse in the past 3 years. She had a past history of head injury following the collapse of a wall on her about 40 years ago. This was associated with the history of loss of consciousness lasting for more than 1 week and trauma to the back that left her bed-bound for more than 3 months. She has had no other neurological symptom since then. She was HIV-negative. Her neurological examination showed no obvious deficits including coordination, position, and vibration sense.
An MRI examination to rule out cerebellar lesions revealed cerebral atrophy (evidenced by reduced cortical gyration volume, prominent ventricles, sulci, and extraaxial fluid spaces) and radiological features suggestive of MS (on FLAIR axial brain MRI showing bilateral periventricular white matter hyperintense lesions similar to what is shown in [Figure 2]). She is presently on steroids and multivitamins and is doing well.
|Figure 2: FLAIR axial MRI of the brain showing bilateral periventricular white matter hyperintense lesions|
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SA was a 61-year-old man from Kano State who presented with a 2-week history of amnesia, generalized body weakness, and titubation. The amnesia was progressive to the extent to which his daily activities and names of his brothers could not be recalled occasionally. He had no preceding history of trauma.
On examination, he was restless and disoriented in time, person and place. There was no focal neurological deficit, visual impairment, or unstable gait. HIV status was negative.
The initial CT scan was normal while on MRI scan, features of MS were seen [Figure 3]. He is presently on steroids and antioxidants and is doing well.
|Figure 3: Showing Axial T2W MRI of the brain in MS patient showing bilateral periventricular white mater hyperintense lesions|
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AM was a 52-year-old teacher from Minna, Niger state who presented with a 3-month history of visual loss in the right eye with retrobulbar pains and amnesia. It was sudden and there was no redness in the eye or body part weakness. He was seen by an ophthalmologist then referred to a neurologist. He underwent brain CT scan, which showed acute ischemic stroke. Six weeks later, he developed a similar loss of vision in the left eye. Further evaluation revealed optic nerve atrophy and optic neuritis. Five months after, he developed gradual paraesthesia and weakness in both legs. His past medical history was unremarkable. He smoked 10 cigarettes/day for >20 years. He was HIV-negative. His MRI of the brain and spine showed features of MS [Figure 4]. At present, he is on prednisolone and his vision has improved remarkably.
|Figure 4: T2W axial MRI of the brain showing hyperintense lesion in the left temporal lobe with no mass effect or midline shift|
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SD was a 19-year old single lady from Zaria, Kaduna State who presented with a 2-month history of progressive weakness in the lower limbs, amnesia, and impaired vision. There was no previous history of trauma, catarrh, food poisoning, or cough. There was no family history of similar illness. She was HIV-negative.
On examination, she was found to be a stable patient. Power was 3/5 in all the limbs. No focal neurologic deficit was noted. Visual acuity: RE = 4/6, LE = 3/6. Fundoscopy was intact. Other systems were stable. CT of the brain was normal. MRI of the brain revealed features suggestive of MS [Figure 5]. She is presently on steroids and antioxidants and is getting better.
|Figure 5: Postcontrast T1W MRI of the coronal brain showing ring-enhancing isointense lesion in the left temporal lobe with absent mass effect in keeping with tumefactive multiple sclerosis|
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| Discussion|| |
The rarity of MS in Blacks, especially Africans is well-documented. However, Blacks who live in countries with a very high incidence tend to have the disease more than those resident in Africa, suggesting an environmental role in the etiology. This environmental contribution is also apparent with the increased incidence of MS noted in countries with higher latitudes and colder climates, regardless of ethnicity.
In South South Nigeria, a case of MS in a 41-year-old university lecturer with the locked-in-syndrome had been reported. Unfortunately, the patient did not have the benefit of either a CSF examination or MRI of the brain. Similarly, a 40-year-old alcoholic farmer was reported in Southeastern Nigeria with recurrent weakness in the lower limbs that progressed to paraplegia and whose MRI of the brain and spine showed features of MS. MS is considered to be uncommon in people of non-Caucasian origin. Yet the prevalence of MS has dramatically increased in Asian countries such as Japan  and Iran  as evidenced by recent epidemiological studies.
Awareness of MS among doctors and laypersons is still very low and specialist care is available to a limited few. Prevalence studies of MS and long-term follow-up of patients presenting with clinically isolated syndromes suggestive of demyelination are lacking. This could probably be due to a clinicoradiological paradox in which case the presentations are not typical with imaging findings on MRI of the brain, which can lead to misdiagnosis. Promising improvements have been made to clarify the pathological specificity and sensitivity of MRI techniques by performing combined histopathologic-MRI correlation studies. Despite these advantages of MRI, some of the limitations of MRI in diagnosing MS include the magnetic field strength, the pulse sequence parameters, partial volume effects, and acute nonenhanced lesions.
Conventional MRI is associated with shortcomings including low sensitivity to gray matter lesions and diffuse white matter involvement and a low capacity to predict clinical status. Advanced structural MRI techniques such as diffusion tensor imaging (DTI), magnetization transfer imaging (MTI), magnetic resonance spectroscopy (MRS), and relaxometry have evolved as superior tools to examine injury in both lesions and normal-appearing brain tissue with more specificity and sensitivity. The application of novel pulse sequences and postprocessing techniques, the use of high-field (3 T) and ultrahigh-field (UHF) >3 T MRI, and combined histopathologic-MRI studies has been playing significant role in the present knowledge on MS.
Typical MS lesions involving typical areas of the brain, the corpus callosum, U-fibers, temporal lobes, brainstem, cerebellum, and spinal cord are best depicted on MRI while CT showed no evidence of such lesions. Typical MRI appearances of MS are — on T1W isotense to hypointense lesions, T2W: Hyperintense lesions, FLAIR; hyperintense lesions, T1W + contrast: Active lesions show enhancement, incomplete enhancement around periphery (open ring sign) seen in tumefactive lesion. In addition, brain atrophy in MS usually appears as enlarged ventricles and the reduced size of the corpus callosum. Recently, numerous quantitative methods have been developed for the precise measurement of global and regional brain tissue losses. Atrophy is seen in all stages in a progressive manner including patients with early MS, emphasizing the need for earlier involvement of neuroprotective intervention. The rate of brain atrophy is higher in MS (0.6-1.0% annually) than in the normal aging process (0.1-0.3% annually).,, Although the exact mechanism of atrophy in MS is not completely clear, it may result largely from myelin and axonal losses. These typical appearances are similar to those seen in these case series.
Tumefactive MS is a variant of MS, which on MRI presents as a large intraparenchymal lesion with usually less mass effect than would be expected for its size. After the administration of gadolinium, there may be some peripheral enhancement, often with an incomplete ring. This is similar to what was seen (on postcontrast MRI images) in the index patient (case number 4) presented in this report. These lesions can be distinguished from gliomas or intraparenchymal abscesses, which typically have a closed-ring enhancement. Occasionally, postinfectious demyelinating disorders may present as multiple cystic lesions. These lesions may have a complete ring enhancement pattern on contrast MRI similar to active MS lesion.
Differential diagnosis for complete ring-enhancing cystic lesions commonly include brain abscess, cysticercosis, tuberculoma, and toxoplasmosis in a tropical country setup. Alternatively, acute disseminated encephalomyelitis (ADEM) may present with cystic lesions that have an open ring enhancement pattern on MRI with gadolinium, which may be of value in differentiating demyelinating from nondemyelinating diseases. MRI lesions in ADEM may be larger, more symmetric in the cerebral and cerebellar hemispheres, and also involve the thalamus more often than in MS. Uniform enhancement of all lesions is considered to favor a diagnosis of ADEM since theoretically all lesions are of the same age unlike MS, which could be active or relapsing lesion. However, the lesions in ADEM may evolve over days to weeks and in such situations, all lesions may not enhance., The presence of Dawson's fingers (lateral ventricles, long axis, perpendicular lesions) and periventricular lesions favor MS more than ADEM. In spite of these distinctions, there is no radiological feature that can confidently distinguish ADEM from the first attack of MS.,
Clinical evidence of complete transverse myelitis coupled with MRI evidence of inflammation of the cord extending three or more vertebral segments is strongly against the diagnosis of MS. Patients with acute partial transverse myelitis characterized by MRI lesions that are asymmetrically placed and spanning fewer than two vertebral segments in length may develop MS.
HIV encephalomyelopathy (HIVE) shows bilateral, symmetrical, and diffuse white matter lesions in the periventricular region and centrum semiovale, with relative sparing of the subcortical white matter and posterior fossa structures. On MRI, these lesions have high T2W and isointense T1W intensity signals and there is no mass effect or contrast enhancement.,
| Conclusion|| |
MS is a rare demyelinating disease in Black Africans; these case reports of Nigerians with clinical and radiological features consistent with MS suggest the need for increased awareness as well as a high index of suspicion among radiologists and clinicians practicing in Africa. The recent availability of MRI in some centers as an imaging of choice will help in the disease's diagnosis and follow-up in most cases.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]