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KEY INFORMATION FOR EMERGENCY MANAGEMENT OF: KENNEDY’S DISEASE – SBMA

BACKGROUND

Kennedy’s disease (KD) or spinal and bulbar muscular atrophy (SBMA), is a rare, adult onset, X-linked neuromuscular disease caused by a CAG repeat mutation in the Androgen Receptor gene.

It is characterised by fasciculation, cramps, and muscle weakness, predominantly affecting the limbs, face and bulbar area. These symptoms may be accompanied by systemic effects related to androgen insensitivity.  Symptoms typically present between the ages of 30 and 50 and it predominantly affects males. Although disabling, 90 % of people with KD have a normal lifespan. Treatment is symptomatic and supportive.

AIRWAY

  • Muscle weakness can affect the jaw, face, mouth, tongue, soft palate and larynx leading to difficulties in chewing, dysphagia and mild dysarthria characterised by nasal speech.
  • Mild episodes of choking episodes are common due to bulbar involvement. Rarely, these can be severe and life threatening.
  • Patients can experience laryngospasm, often accompanied by stridor. This can be triggered and exacerbated by gastro-oesophageal reflux and upper airway infections. Although these events can be frightening and distressing, they seldom escalate to prolonged episodes. Techniques such as straw breathing can be helpful to manage these events. Pharmaceutical interventions may be indicated in severe cases and recurrent episodes.
  • Particular attention is warranted during endotracheal extubation due to the risk of laryngospasm. Severe postoperative glottic oedema has also been reported.

BREATHING

  • Minor breathing difficulties have been reported in KD, but non-invasive ventilation is rarely needed (0.5% of patients in a recent survey). Breathing muscles are typically spared from weakness.
  • Dysphagia can lead to recurrent aspiration pneumonias. Pneumonia is identified as the most frequent cause of premature death (10% of patients).
  • Pulmonary function testing may be advised pre-operatively.
  • The action of depolarising blocking agents, such as Succinylcholine, can be prolonged or enhanced in KD patients. When using neuromuscular blocking drugs, it is necessary to observe the degree of relaxation using a muscle relaxation monitor.

CIRCULATION

  • In rare cases (1-2% but possibly higher in patient of Asian descent), KD patients can develop Brugada-like Syndrome. ECG atrial high lead placement is useful in detecting Brugada syndrome. If detected, specific antiarrhythmic, psychotropic, anaesthetics and analgesic drugs should be avoided (a list can be found here: https://www.brugadadrugs.org/avoid/
  • KD patients can present with raised Troponin T and CK unrelated to cardiac damage. Troponin I testing should be preferred or used alongside Troponin T when evaluating potential cardiac damage.
  • Subclinical autonomic dysfunction has also been reported in KD patients.

 

DISABILITY

  • KD affects predominantly the lower motor neurones and skeletal muscle. Deep tendon reflexes will be diminished.
  • Patients may present with sensory disturbances in the distal lower limbs.
  • Balance and mobility issues are common, so early assessment by physiotherapy and occupational therapy (PT/OT) is recommended to mitigate fall risks. Early mobilisation and sitting out of bed should be encouraged as soon as medically appropriate to reduce deconditioning and minimise care needs at discharge.
  • Cognitive and neuropsychological function is normal in KD.

EXPOSURE

  • High prevalence of insulin resistance, metabolic syndrome and non-alcoholic liver disease has been reported in KD.
  • Statins are not usually prescribed due to the potential for statin induced myopathy.
  • Elevated aspartate aminotransferase, alanine aminotransferase and lactate. dehydrogenase along with low creatinine are indicative of muscle pathology.
  • Osteopenia is common and people with KD can be more susceptible to fractures following falls.

SOURCES

  • Alqahtani A, Kokkinis A, Zizzi C, et al. Patient-reported impact of symptoms in spinal and bulbar muscular atrophy. Neurol Clin Pract. 2023;13(6):e200213. doi: 10.1212/CPJ.0000000000200213 PMID: 39140081 PMCID: PMC11318780
  • Manzano R, Sorarú G, Grunseich C, Fratta P, Zuccaro E, Pennuto M, Rinaldi C. Beyond motor neurons: expanding the clinical spectrum in Kennedy’s disease. J Neurol Neurosurg Psychiatry. 2018 Aug;89(8):808-812. doi: 10.1136/jnnp-2017-316961. Epub 2018 Jan 20. PMID: 29353237; PMCID: PMC6204939.
  • Niesen AD, Sprung J, Prakash YS, Watson JC, Weingarten TN. Case series: anesthetic management of patients with spinal and bulbar muscular atrophy (Kennedy’s disease). Can J Anaesth. 2009 Feb;56(2):136-41. doi: 10.1007/s12630-008-9018-1. Epub 2009 Jan 10. PMID: 19247761.
  • Pradat PF, Bernard E, Corcia P, Couratier P, Jublanc C, Querin G, Morélot Panzini C, Salachas F, Vial C, Wahbi K, Bede P, Desnuelle C; French Kennedy’s Disease Writing Group. The French national protocol for Kennedy’s disease (SBMA): consensus diagnostic and management recommendations. Orphanet J Rare Dis. 2020 Apr 10;15(1):90. doi: 10.1186/s13023-020-01366-z. PMID: 32276665; PMCID: PMC7149864.
  • Practical Guidance for Patients : Living with KD : Kennedy’s Disease Association (kennedysdisease.org)

Reviewed and approved on 12th November 2024 by:

Carlo Rinaldi, Dipa Jayaseelan and Pietro Fratta

Consultant Neurologists – Kennedy’s Disease Clinical and Research Service  

National Hospital for Neurology and Neurosurgery – University College London Hospitals

Dr. Christopher Grunseich – Head of the Inherited Neuromuscular Diseases Unit, NINDS