Stiff Person Syndrome - Signs and Symptoms

Signs and Symptoms

Individuals with stiff person syndrome tend to present in 3 different stages: early, late and end stage. In the early stages, there are few objective findings indicating SPS during the initial assessment. SPS will begin insidiously in the axial muscles. Patients will present with an exaggerated upright posture and have stiffness and pain in the whole back. Sleep disturbances are also common due to muscle spasms waking them. In the late stages, proximal limb muscle become involved and the patient tends to move slower as fast movements will cause the severe spasms. Emotions such as anger have been shown to have a link to causing the spasms, which begin in this stage. Exaggerated lumbar lordosis becomes more evident in the patients. Depression can be comorbid with SPS at this stage due to the patient’s quality of life decreasing. In the end stage, activities of daily living such as eating and simple movements become hard to perform. Skeletal fractures and muscle ruptures occur quite often along with joint deformities.

Those with the illness experience progressive, fluctuating tonic muscle contractions, particularly the axial musculature. These spasms occur in response to environmental stimuli such as voluntary or passive movements, and unexpected somatosensory or auditory stimulation. Often changes in emotion or stress can trigger spasms as well. Common signs of SPS found during assessment are hypertonia, hyperreflexia and rigidity of muscles.

Reflexive integrity in individuals with stiff person syndrome can be assessed via deep tendon reflexes as well as resistance to passive stretch. Deep tendon reflexes are graded using a 0 to 4+ scale. 0 indicates absent reflexes, 1+ indicates hypoactive (decreased) reflexes, 2+ indicates normal reflexes, 3+ indicates hyperactive (increased) reflexes without clonus and 4+ indicates hyperactive reflexes with clonus. During the examination, individuals with stiff person’s syndrome are likely to have deep tendon reflexes which are graded at 2+ (normal) or 3+ (increased reflexes). Furthermore, they are likely to exhibit increased startle reflex as well as an increased head retraction reflex (HRR).

Symptoms begin in the region of the trunk and the lower extremities before moving proximally in the upper limbs, and eventually affecting facial and laryngeal muscles used for swallowing and speech. Depression and anxiety are often noted although this may be a result of discomfort due to stiffness, rather than underlying neurochemical abnormalities. MRI detection of GABA in the brain have demonstrated reduced levels in stiff-person syndrome.

In the variant Stiff-limb syndrome, symptoms present focally affecting one or more limbs. Motor symptoms occur predominantly in distal limb muscles rather than axial muscles. However, when patients experience severe spasms, motor symptoms can be seen in the trunk, upper extremities and face. Increased distal limb stiffness in ankles and feet leads to feet being in constant plantar flexion. This in turn affects posture during gait and increases fall risks for the patient.