Werdnig-Hoffman disease (also known as "Infantile spinal muscular atrophy", "spinal muscular atrophy type 1", or "spinal muscular atrophy type I") is an autosomal recessive muscular disease. It is the most severe form of spinal muscular atrophy. Werdnig-Hoffman affects the lower motor neurons only. It has been linked to an abnormal survival motor neuron (SMN) gene.
It is evident before birth or within the first few months of life. There may be a reduction in fetal movement in the final months of pregnancy. Symptoms include floppiness of the limbs and trunk, feeble movements of the arms and legs, swallowing and feeding difficulties, and impaired breathing. Affected children never sit or stand unassisted and will require respiratory support to survive before the age of 2. Other symptoms include:
- Fasciculations of the tongue
- Marked Hypotonia in Proximal, Distal muscles, Intercostals & bulbar muscles (Patient lies in a Frog-Leg position,i.e. hips abducted & knee flexed)
- Flaccid Quadriplegia
- Difficulty breathing
- Poor feeding - need gastrostomy
- Weak cry
- Areflexive extremities
- Normal Intelligence
- Electro-Myelo Gram (EMG) will show Fibrillation & Muscle Denervation
- Serum Createnine-Kinase may be normal or Increased
Treatment is symptomatic and supportive and includes treating pneumonia, curvature of the spine and respiratory infections, if present. Also, physical therapy, orthotic supports, and rehabilitation are useful. For individuals who survive early childhood, assistive technology can be vital to providing access to work and entertainment. Genetic counseling is imperative.
The patient's condition tends to deteriorate over time, depending on the severity of the symptoms. Children with Werdnig-Hoffman disease / SMA Type 1 face a difficult battle. They are constantly at risk of respiratory infection and pneumonia. Feeding difficulties make it a real challenge for parents to give their children adequate nutrition and supplemental feedings may be required. Tubes placed through the nose or directly onto the stomach may be necessary. Recurrent respiratory problems mean that mechanical support for breathing - usually initially in the form of BiPAP and later often tracheostomy and ventilation - are necessary for the baby to have any chance of long-term survival. Affected children never sit or stand and usually die before the age of 2 if the decision is made not to provide breathing support. However, some individuals have survived to become adults, in which case sexual function is unimpaired.