What is the management approach for Kennedy Disease (Spinal and Bulbar Muscular Atrophy, SBMA)?

Management of Kennedy Disease (Spinal and Bulbar Muscular Atrophy)

Kennedy disease requires multidisciplinary symptomatic management centered on rehabilitation strategies, respiratory monitoring, nutritional support, and treatment of endocrine abnormalities, as there is no disease-modifying therapy currently available. 1

Initial Evaluation and Diagnosis Confirmation

The diagnosis should be confirmed in a tertiary referral center for motor neuron diseases with genetic testing showing CAG repeat expansion >37 (typically >40) in the androgen receptor gene. 2, 1 The initial comprehensive assessment must include:

• Neurological evaluation: Document the pattern of lower motor neuron weakness (typically starting in lower limbs), bulbar involvement (dysarthria, dysphagia), muscle cramps, and tremor 2, 1
• Electromyography: Identify diffuse motor neuron involvement with denervation patterns and assess for sensory nerve involvement 1, 3
• Cardiac screening: ECG to detect repolarization abnormalities including Brugada syndrome risk 1
• Endocrine assessment: Evaluate for gynecomastia, signs of androgen resistance, glucose intolerance, and hyperlipidemia 1
• Baseline functional assessment: Use standardized motor function scales to document strength and functional capacity 1

Core Management Components

Neuromuscular and Rehabilitation Management

Physical therapy should focus on submaximal, functional, and aerobic exercise while avoiding excessive resistive and eccentric exercise to prevent overwork weakness. 4

• Implement gentle strengthening within physiological limits with adequate rest periods to avoid overexertion 4
• Provide regular assessment every 6 months to monitor disease progression and adjust interventions 5, 6
• Prevent contractures through stretching, positioning, and orthotic intervention as needed 4
• Optimize function with adaptive devices and assistive technology when weakness progresses 4

Bulbar and Respiratory Management

Speech therapy and nutritional evaluation by an expert dietician are essential components of care, with enteral nutrition (gastrostomy) required when dysphagia becomes severe. 1

• Monitor swallowing function regularly and implement dietary modifications (texture-modified foods, thickened liquids) as dysphagia progresses 1
• Screen for aspiration pneumonia risk and provide chest physiotherapy, drainage, positioning, and breath stacking techniques 1
• Consider mechanical insufflation-exsufflation and cough assist devices for secretion management 1
• Non-invasive ventilation is seldom needed but should be available if respiratory failure develops 1

A critical pitfall is underestimating respiratory complications—aggressive management of bronchial obstructions and aspiration pneumonia with antibiotics is necessary, as aspiration pneumonia can be fatal. 1, 7

Cardiac Monitoring

Regular cardiac surveillance is required given the association with Brugada syndrome and cardiac repolarization abnormalities. 1 Perform baseline ECG and periodic monitoring, with cardiology referral if abnormalities are detected. 1

Endocrine and Metabolic Management

Symptomatic pharmaceutical therapy should address pain, glucose intolerance, and hyperlipidemia, but there is no evidence supporting androgen substitution therapy. 1

• Manage glucose intolerance and hyperlipidemia with standard medical interventions 1
• Address gynecomastia if causing significant distress, though it does not require routine intervention 1
• Do not prescribe androgen replacement therapy as it lacks evidence and may worsen symptoms 1

Pain and Symptom Management

Muscle cramps are a common and distressing symptom requiring pharmacological management. 2, 1 Consider medications for tremor control when functionally limiting. 2

Monitoring Schedule and Follow-up

• Routine clinic visits every 6 months with the multidisciplinary team including neurology, rehabilitation medicine, speech therapy, and nutrition 5
• Functional assessments using standardized scales at each visit to track disease progression 1
• Annual cardiac screening with ECG 1
• Regular nutritional assessments to monitor weight and swallowing function 1

Psychosocial Support

Designate a care coordinator to serve as the primary point of contact for the patient and family, providing continuity and navigation through the healthcare system. 5

• Screen for depression and anxiety, which are common in chronic progressive neuromuscular diseases 5
• Provide psychological support for emotional adjustment and coping 5
• Facilitate support groups and connections with patient advocacy organizations 5

Important Clinical Considerations

The disease course is typically slowly progressive with walking ability preserved until late in life, and life expectancy is only slightly compromised in most cases. 2 However, atypical presentations with rapid progression can occur, particularly when bulbar symptoms are prominent. 7

Aspiration pneumonia represents the most significant mortality risk and requires aggressive preventive strategies and early treatment. 1, 7 Respiratory failure requiring ventilatory support is uncommon but should be anticipated in advanced disease. 2, 1

A common pitfall is confusing Kennedy disease with amyotrophic lateral sclerosis (ALS)—key distinguishing features include the X-linked inheritance pattern, sensory involvement, endocrine abnormalities, and slower progression in Kennedy disease. 2, 8 However, preserved or brisk reflexes can occasionally occur in Kennedy disease, potentially causing diagnostic confusion. 7