Progressive Non-Infectious Anterior Vertebral Fusion

Progressive non-infectious anterior vertebral fusion (PAVF) is an early childhood spinal disorder characterized by the gradual onset of thoracic and/or lumbar spine ankylosis often in conjunction with kyphosis with distinctive radiological features.

Epidemiology

Prevalence is unknown, but PAVF (mostly isolated cases) has been reported in approximately 80-100 cases. Girls (60%) seem slightly more affected than boys.

Clinical description

Onset is in early childhood and often discovered in young children while exploring a spinal deformity. This is the start of the progressive anterior vertebral ankylosis in the thoracic and/or lumbar areas observed during the disease course (months or years after onset) often clinically manifested by thoracolumbar kyphosis. The anterior vertebral ankylosis extends with time to the posterior part. PAVF usually presents with mild pain, stiffness of neck and/or back with developing thoracolumbar kyphosis. Often however PAVF is asymptomatic. Neurological abnormalities are exceptional. PAVF can occur isolated or less frequently, as part of a syndrome. Syndrome associated manifestations include facial dysmorphism, absence of one cervical vertebrae, radio-ulnar synostosis, exostosis, generalized overgrowth, split cord malformation and/or situs inversus totalis (see this term).

Etiology

Etiology is unknown.

Diagnostic methods

PAVF may be discovered fortuitously. MRI and X-ray confirm PAVF when distinctive radiological features of PAVF are present. MRI examination is favored, since the precise degree of the intervertebral ankylosis of the disc condition can be evaluated. The typical anterior vertebral endplate narrowing associated with irregularities and osteosclerosis of the vertebral corners may be visible early on.

Differential diagnosis

Synspondylism (see this term), spondylothoracic dysplasia and familial Scheuermann disease (see this term) should be considered in the differential diagnosis. Other differential diagnoses in case of infection include infectious spondylodiscitis and congenital vertebral block.

Management and treatment

Conservative treatment includes a routine annual or semestrial (during pubertal growth spurt) clinical and medical imaging check-up and a multi-disciplinary approach. It seems very important to prevent sagittal imbalance at a very young age by a regular clinical monitoring and early bracing as soon as hypolordosis appears. At adult age, bracing has a very limited effect. Surgical treatment has to be discussed on an individual basis. In some patients presenting with lumbar hypolordosis, a lordotic restoration using Boston-type braces with progressive correction, assists in addressing chronic pain in addition to class 1 WHO painkillers. PVO (posterior vertebral osteotomies) can be considered in patients when restoring a satisfying sagittal balance is impossible or very challenging. In patients with moderate deformities but with severe chronical pain, posterior intervertebral fusion is useful. Long term follow-up is recommended.

Prognosis

Prognosis is fairly good as it does not involve vital issues. However, almost all patients complain with low back pain and junctional thoraco-lumbar pain.