|Year : 2014 | Volume
| Issue : 1 | Page : 42-44
Foramen magnum syndrome from a tumor in a neurofibromatosis type 1 patient
Lukman Femi Owolabi1, Hassan Mohammed2, Ibrahim Daiyabu Alhaji3
1 Department of Medicine, Neurology Unit, Aminu Kano Teaching Hospital, Bayero University, Kano, Nigeria
2 Department of Dermatology Unit, Aminu Kano Teaching Hospital, Bayero University, Kano, Nigeria
3 Department of Rheumatology Unit, Aminu Kano Teaching Hospital, Bayero University, Kano, Nigeria
|Date of Web Publication||18-Sep-2014|
Lukman Femi Owolabi
Department of Medicine, Neurology Unit, Aminu Kano Teaching Hospital, Bayero University, P.M.B 3452, Kano
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Foramen magnum tumors are rare in neurofibromatosis type 1. They may present with bizarre symptoms and may mimic many neurological conditions. We report a case of foramen magnum syndrome secondary to tumor misdiagnosed as cervical spine tuberculosis.
Keywords: Foramen magnum syndrome, neurofibromatosis, tumor
|How to cite this article:|
Owolabi LF, Mohammed H, Alhaji ID. Foramen magnum syndrome from a tumor in a neurofibromatosis type 1 patient. Ann Nigerian Med 2014;8:42-4
| Introduction|| |
Neurofibromatosis type 1 (NF1) is a genetic disorder, with incidence of one in 2500-3300,  that can affect multiple systems of the body. NF1 is characterized by the presence of cafe au lait spots, peripheral neurofibromas, Lisch nodules, axillary freckling, and skeletal dysplasia.
Apart from the major cutaneous presentations, NF1 may be complicated by several nervous system diseases. Tumors of the peripheral nervous system are the most frequent tumors of NF1, and malignant peripheral nerve sheath tumors are the major cause of mortality in adult patients.  Central nervous system (CNS) tumors, though less frequent than peripheral nervous system tumors, are important because of their greater impact on morbidity and mortality.  Of the CNS tumors in NF1, optic pathway tumors are the most common, accounting for about 66% of all CNS tumors. Out of the extra-optic pathway tumors, brainstem tumors appear to be the most common. Spinal cord tumors account for 1% of all CNS tumors in NF1.  Tumor located at the junction between the brainstem and spinal cord are uncommon.  Thus, foramen magnum syndrome from such a tumor is a rare clinical entity in neurofibromatosis. We report a case of clinico-radiologically diagnosed foramen magnum syndrome secondary to a tumor in a NF1 patient.
| Case report|| |
A 28-year-old male petty trader presented in our hospital with a 2-year history of progressive neck pain, abnormal sensation, and numbness in the upper and lower extremities; which was more in the lower extremities than in the upper extremities. There was associated clumsiness of the hands, weakness of the limbs; first involving both arms, followed by the left leg and subsequently the right leg. This culminated in inability to walk or use his hands. There was no history of headache, vomiting, dysphagia, dizziness, diplopia or sphincteric disturbance. Before presenting to our facility, he was diagnosed to have cervical spine tuberculosis and hence, was commenced on treatment for tuberculosis.
Skin examination revealed widespread subcutaneous nodules distributed all over his body [Figure 1] with axillary freckles bilaterally. On neurological examination, he had limitation of neck movement in every direction because of neck pain. The cranial nerves were intact. He had slight atrophy of intrinsic hand muscles and quadriparesis with power grade 1 and 2 in the upper and lower limbs respectively. The tone and deep tendon reflexes of all the extremities were brisk and his plantar responses were extensor bilaterally, but jaw jerk was normal. There was reduced sensation to touch and pain up to C2 level and Lhermitte's sign was present. However, joint position sense and vibration sense were intact. Findings on cardiovascular, respiratory and abdominal examinations were unremarkable.
In view of the clinical findings, diagnosis of foramen magnum syndrome from a tumor was made.
X-ray of the cervical spine did not show any abnormality. Magnetic resonance imaging (MRI) of the brain and spinal cord revealed a mass at the level of the foramen magnum extending from the lowermost brainstem to C1-C2 cervical spinal column [Figure 2]. Findings of other investigations including hematological, biochemical and microbiological tests were within normal limits. Anti-tuberculous medications were stopped and the patient was referred for neurosurgical intervention.
|Figure 2: Sagittal T1 (a) and T2-weighted magnetic resonance image obtained in the patient, demonstrating an anteriorly situated foramen magnum tumor (arrow) causing compression and displacement of the caudal brainstem and rostral spinal cord|
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| Discussion|| |
The initial diagnosis for which the patient started receiving treatment was tuberculosis affecting cervical spine traumatic birth syndrome (TBS). This diagnosis was considered less likely in view of rarity of the cervical spine involvement in tuberculosis of the spine  and the clinical features that were rather atypical of TBS. The temporal profile of classic foramen magnum syndrome is characterized by the occurrence of unilateral arm sensory and motor deficits, which progress to the ipsilateral leg, then the contralateral leg, and finally contralateral upper extremity. The symptoms that our patient presented with, the temporal profile and pattern of weakness that is "around the clock" weakness were suggestive of foramen magnum syndrome.
Nevertheless, the clinical appearance of foramen magnum tumor is protean and even at the stage when serious neurological deficits are present, the lesions are often misdiagnosed as another neurological disease.  Although foramen magnum lesions including tumors may give rise to many bizarre symptoms, several reports have taken note of the pitfalls in their diagnoses. 
In a detailed analysis of clinical manifestations of foramen magnum syndrome involving 57 cases from various causes by Yasuoka et al.,  dysesthesia, numbness, and a tingling sensation in the hands, and neck pain, were the most frequent complaints. Our patient presented with similar symptom profile.
In this patient, the diagnosis of NF1 was made based on the National Institutes of Health Consensus Development Conference formulated diagnostic criteria for NF1.  Advancement in the understanding of the disease indicates that in addition to peripheral lesions such as a subcutaneous mass or neurofibroma, many CNS lesions were often found in NF1 patients.  Studies have shown repeatedly that NF1 patients have a higher incidence of both peripheral and CNS tumor incidence than the general population. ,,,, Thus, clinicians who cater for NF1 patients should have a low threshold for evaluation for these CNS tumors. Moreover, some authorities are of the opinion that at least one brain imaging study is mandatory for each NF1 patient to screen for possible CNS lesions, even if the patient has no symptoms and signs of CNS involvement. 
Brain tumors are the second most common tumors that occur in individuals with NF1. Most of the brain tumors that occur in NF1 are low-grade astrocytomas. They can occur anywhere in the brain, but most often occur along the optic pathway; and tumors at the junction between the spinal cord and medulla are relatively uncommon. 
In addition, in NF1 patients, certain CNS objects namely "neurofibromatosis bright objects" and "unidentified bright objects" have been described. , They are usually located in the basal ganglia, thalamus, hippocampus, and brain stem. These lesions, which may remain stable or disappear over several years, may undergo cancerous transformation into brain gliomas. ,
The clinical differential diagnosis of foramen magnum syndrome secondary to a tumor includes cervical spondylosis, amyotrophic lateral sclerosis, syringomyelia, and multiple sclerosis. ,,
Although its clinical presentation is highly variable, the diagnosis of foramen magnum syndrome should be considered in a NF1 patient with occipital neck pain and quadriparesis. High index of suspicion as well as detailed neurological assessment will be of benefit in clinching the diagnosis in such a patient.
| Conclusion|| |
The case presented demonstrated that NF1 may present with foramen magnum syndrome from a tumor, and can be easily misdiagnosed as other neurological diseases. High index of suspicion is required for its diagnosis which can be confirmed using MRI technique.
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[Figure 1], [Figure 2]