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OA: Clinical Case Report (CARE Compliant)

Sudden bilateral lower limb paralysis with dural ectasia in Neurofibromatosis type 1

A case report

Mutua, Victor BSc Physiologya,∗; Mong’are, Newnex BSc Physiology, MBChBa; Bundi, Brian BSc Anatomy, MBChBa; von Csefalvay, Chris MA(Oxon), FRSPHb; Oriko, David MBChBa; Kitunguu, Peter BSc Anatomy, MBChB, MMEDa

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Medicine Case Reports and Study Protocols: September 2021 - Volume 2 - Issue 9 - p e0165
doi: 10.1097/MD9.0000000000000165
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1 Introduction

Neurofibromatosis is a heterogeneous group of genetic diseases that results in tumors of the central and peripheral nervous systems.[1] While mostly hereditary, spontaneous developing cases have also been documented. The most common form is neurofibromatosis type 1 (NF-1, 96%), followed by neurofibromatosis type 2 (3%), and a lesser known form, schwannomatosis.[1]

Both hereditary forms of NF-1 and neurofibromatosis type 2 follow an autosomal dominant pattern of inheritance; therefore, only 1 faulty gene is required from the parents for the offspring to develop the disease. In both hereditary and spontaneous NF, the mutations involve tumor suppressor genes, whose mutation leads to uncontrolled division of cells, resulting in the neurofibromas characteristic of the disease.[2] Neurofibromas are generally indolent, slow-growing tumors thatcommonly affect the skin, but can also affect other regions, notably the central nervous system.

The hallmarks of NF-1 symptoms are primarily cutaneous neurofibromas, skin café-au-lait spots, and skinfold freckling.[3] Other manifestations include pigmentary abnormalities, skeletal dysplasia, and low-grade gliomas.[4] The condition is progressive and symptom burden typically accumulates over the patient's lifespan, with life expectancy of NF-1 approximately 8 to 12 years lower than that of healthy controls.[5]

To the best of our knowledge, no report has hitherto described a patient with NF-1 who developed sudden bilateral lower limb paralysis with no evidence of cord compression on imaging studies. In this case report, we describe a 30-year old male with NF-1 who developed sudden bilateral lower limb paralysis following a mild trauma, and discuss the clinical features and associated complications of the disease.

2 Case presentation

A 30-year-old male presented with sudden-onset bilateral lower limb paralysis and lower back pain, which he stated began just after he fell while trying to stand up from his seat. He stated that he was not able to stand up or feel his lower limbs. The patient walked to work that day, where he worked as a secretary. He denied any prodromic signs that preceded the fall, such as pain, confusion, or body weakness. There was no prior history of back pain, significant illness, or lifting of heavy objects. According to the patient, he developed lower limb paralysis and lower back pain only after the fall. In addition to lower limb paralysis and lower back pain, the patient also complained that he was unable to pass urine or stool.

The patient did not present with any symptoms suggestive of pulmonary tuberculosis (TB) and was not previously treated for TB. He had no history of any other motor symptoms (such as previous episodes of muscle weakness, loss of balance, or coordination issues) or sensory symptoms prior to that day.

Upon physical examination, the lungs, heart, and abdomen were unremarkable, and the patient exhibited normal vision and hearing, with no abnormalities of the eye and no Lisch nodules. A neurological examination showed a Glasgow Coma Score of 15/15, normal muscle bulk, but a muscle power grade of 0 in all muscle groups of the lower limbs. The patellar tendon and Achilles tendon reflex, as well as plantar extensor response, were absent bilaterally. Sensation was absent in the T11 dermatome.

The patient's liver function test, renal function test, serum electrolyte levels, and C-reactive protein levels were normal upon admission. His plasma lactate dehydrogenase level was normal at 118 U/L (reference range, 109–245). He tested negative for HIV, anti-nuclear antibodies, and rheumatoid factor. The GeneXpert test for TB from sputum was negative. Cerebrospinal fluid biochemistry was normal, and a Ziehl-Neelsen stain for acid-fast bacilli was negative.

Chest radiography was performed to rule out pulmonary tuberculosis, as Pott disease was initially entertained as a differential. The chest X ray was normal and did not support the diagnosis of TB or Pott disease. A lumbar sacral radiograph (Fig. 1) showed an enlarged vertebral canal but no vertebral fractures. Magnetic resonance imaging (MRI) of the spine (Fig. 2) showed a normally maintained kyphotic curvature of the dorsal spine. No evidence of spondylolisthesis was found. The intervertebral discs were normal in morphology, facet joints were normal at all levels, and pre/paravertebral collection was observed. Posterior erosion/scalloping of the vertebral bodies was observed at L2 to L5 and S1. The vertebral canals in the lumbar and sacral segments were markedly increased. There was no evidence of cord compression on either the computed tomography or MRI. It was only after repeated MRI studies that herniation of nerve root sleeves, with marked compression of traversing nerve roots, was noted.

Figure 1:
X- ray: Widened vertebral canal at the lumbar vertebra.
Figure 2:
MRI scan: Sagittal MRI showing dural ectasia with posterior vertebral scalloping from L2 to L5 and S1. Herniation of nerve root sleeves with compression of traversing nerve roots and lateral meningoceles were also noted.

The diagnosis of NF-1 was made using the clinical diagnostic criteria agreed upon at the consensus meeting of the National institute of Health [Table 1] (NIH criteria).[6] The patient showed characteristic subcutaneous nodules over the face and trunk associated with café-au-lait spots, but no axillary or inguinal freckling. The patient's mother and all 4 siblings had similar subcutaneous nodules. The patient reported that these subcutaneous neurofibromas have been present since childhood. This led to the diagnosis of NF-1.

Table 1 - NIH Diagnostic criteria for type 1 neurofibromatosis.
Two or more of the following criteria are required for diagnosis:
1. Six or more café-au-lait spots over 5 mm in prepubertal individuals and over 15 mm in postpubertal individuals
2. Two or more neurofibromas of any type or 1 plexiform neurofibroma
3. Freckling in the axilla or groin
4. Optic glioma
5. Two or more Lisch nodules
6. Presence of a distinct osseous lesion, sphenoid wing, dysplasia or thinning of a long bone with or without pseudoarthrosis
7. A first degree relative who meets the above criteria for NF1.
NF-1 = neurofibromatosis type 1.

No treatment was initiated specifically for NF-1. In the hospital, the patient received analgesics, antibiotic cover (gentamicin and cefuroxime) for management of a urinary tract infection that the patient developed in the ward, lactulose (to manage constipation), and enoxaparin (prophylactic anticoagulation). There was no improvement in NF symptoms. The patient eventually developed sepsis, and following a clinical decline, he succumbed to his illness 6 weeks after admission. Sepsis is thought to be a complication of urinary tract infection and not directly linked to NF-1.

3 Discussion

We present a case involving a 30-year-old man with NF-1 who developed bilateral lower limb paralysis. Although his NF-1 gene was not investigated, he was diagnosed with NF-1 based on the clinical criteria established at the National Institutes of Health consensus conference.[6] The clinical diagnosis of NF-1 relies on identifying at least 2 of the following 7 diagnostic criteria: neurofibromas, café-au-lait macules, Lisch nodules, skinfold freckling, optic pathway tumors, family history, or bone dysplasia.[7] In addition to the 7 diagnostic criteria, there are other features that are increasingly reported as common manifestations of NF-1. These include motor deficits, muscle weakness, and poor coordination.[8,9] Historically, these deficits in NF-1 were solely attributed to central nervous system dysfunction from intracerebral neurofibromas, although recent studies have shown a role for the NF-1 gene product, neurofibromin, in metabolism and muscle growth, which may indicate a more direct effect.[7]

Dural ectasia is a circumferential expansion of the dural sac and has been frequently reported to be associated with NF-1, with as many as 70% to 80% of all cases of dural ectasia found in patients with NF-1.[10] Dural ectasia is also associated with Marfan syndrome, Ehlers-Danlos syndrome, and ankylosing spondylitis, and may also occur idiopathically.[11] The expanding dura can cause erosion of the vertebral body and pedicle, and may in severe forms result in destabilization, fracture, or dislocation of the spine. Destabilization of the spine due to severe erosion of the vertebral bodies in NF-1 can occasionally lead to spontaneous subluxation or dislocation and, subsequently, spinal cord injury.[12–14] Spinal deformity is the most common orthopedic complication in NF-1, classified into non-dystrophic and dystrophic types based on the absence or presence, respectively, of skeletal deformities on plain radiographic evaluation.[15,16] Dystrophic changes include vertebral scalloping, widened spinal canal and foramina, rib penciling, elongated and attenuated pedicles, and associated paraspinal masses.[15,17,18] Our patient presented with dural ectasia and vertebral scalloping localized mainly at the lumbar vertebrae, with evidence of herniation of nerve root sleeves with compression of traversing nerve roots on MRI.

Nakamura et al. reported 7 cases of NF-1 with symptoms of spinal cord compression following mild trauma.[19] Imaging studies of all 7 cases showed dysplastic changes associated with NF-1, including vertebral scalloping, dural ectasia, and paravertebral soft tissue mass. Following the recognition of spinal deformities, stabilization of the vertebral column can be achieved either through posterior fixation and/or anterior fixation.[18,20] Posterior fixation is preferred because anterior fixation is associated with a higher risk of dural injury and uncontrollable leakage of cerebrospinal fluid.[19] These 2 procedures were the mainstay treatment in Nakamura's study and resulted in a good outcome in 6 out of 7 patients.[19]

While our patient presented with features of cord compression, there was no evidence of cord compression, vertebral subluxation, or dislocation. It was only after repeated MRI studies that herniation of nerve root sleeves with marked compression of traversing nerve roots was noted. This was thought to account for the patient's neurological symptoms. The patient unfortunately developed sepsis, while in the ward and succumbed before a multidisciplinary team could discuss his definitive management.

Based on these findings, it should be noted that dystrophic changes in NF-1 might lead to rapid aggravation of neurological symptoms even after a mild trauma, and that these patients may present with or without evidence of cord compression on imaging. Clinicians should anticipate both dystrophic changes and orthopedic complications associated with NF-1, such as spinal cord injuries, which, if managed early, may have a favorable clinical outcome.

3.1 Uncited reference


Author contributions

Conceptualization: Victor Mutua.

Informed consent: Written consent was obtained from the patient for publication of the case details.

Investigation: All authors

Writing – original draft: Victor Mutua, Newnex Brian Mong’are, Brian Nyamweya Bundi.

Writing – review & editing: Victor Mutua, Newnex Brian Mong’are, Brian Nyamweya Bundi, David Oriko, Peter Kitunguu, Chris von Csefalvay.


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case report; dural ectasia; neurofibromatosis type 1

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