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Neurological soft signs

What are neurological soft signs in bipolar disorder?

Neurological soft signs (NSS) are abnormalities identified by clinical examination. They are referred to as ‘soft’ because they are not related to a localised pathological lesion and are not part of a well-defined neurological syndrome.

NSS can be grouped into three categories: integrative sensory functioning, motor coordination, and complex motor sequencing. Integrative sensory functioning includes deficits in bilateral extinction (difficulty perceiving stimuli when presented to both hemispheres simultaneously), impaired audio-visual integration, agraphaesthesia (inability to recognise by touch letters and numbers drawn on the skin) and astereognosis (inability to identify an object by touch without visual input). Motor coordination involves general coordination, intention tremor, finger thumb opposition, balance, and gait. Motor sequencing measures complex motor tasks, such as repetitive alternating hand positions. Abnormalities in eye movements and developmental reflexes may also be apparent.

What is the evidence for NSS in people with bipolar disorder?

Moderate quality evidence suggests a large effect of more NSS in people with bipolar disorder than controls. This effect remained large in the subgroup analyses of bipolar disorder type, in euthymia patients, and in task type. Tasks included sensory integration, motor coordination, or motor sequencing. There were no moderating effects of age, sex, duration of illness, age of onset, or antipsychotic use.

Moderate to high quality evidence found a medium-sized effect of less NSS in people with bipolar disorder than in people with schizophrenia. Subgroup analyses showed only motor coordination scores were significantly lower in bipolar disorder. There were also no significant differences between people with bipolar disorder with psychotic symptoms, and people with schizophrenia. There were no moderating effects of age, sex, duration of illness or age of onset.

September 2021

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Last updated at: 12:49 am, 8th October 2021
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