Journal of Neurology, Neurosurgery, and Psychiatry 1992;55:585-589 585 Risk of sudden death during sleep in J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.7.585 on 1 July 1992. Downloaded from syringomyelia and syringobulbia Martin A Nogues, Ricardo Gene, Horacio Encabo Abstract Patients and methods Clinical, respiratory, and polysom- Case 1 nographic findings in three patients with This 54 year old man first noticed dizziness, syringomyelia and syringobulbia who dysphagia, and dyspnoea at the age of 37. A developed severe respiratory complica- diagnosis of syringobulbia and syringomyelia tions are described. Neurological exam- was made at that time. Though he was treated ination showed evidence of IXth and with radiotherapy, his condition worsened. He Xth cranial nerve involvement with then remained stable for 15 years, after which dysphagia and dysphonia, but there were he noticed progressive weakness of all four no complaints of serious sleep difficulties. limbs. He had been born by an abnormal Two patients died during sleep and the delivery with forceps, suffering postnatal other was resuscitated during a nap. AUl asphyxia. patients showed moderate restrictive ven- On examination in March 1988 his overall tilatory defects with reduced maximal appearance was normal, but he had noticeable buccal pressures and one also showed a wasting and weakness of the shoulder girdle. low ventilatory response to CO2 rebreath- He had an ataxic gait, a left Horner's syn- ing. Protracted central, obstructive, and drome, horizontal and vertical nystagmus, mixed apnoeas and hypopnoeas were definite wasting and weakness of proximal commonly observed during sleep. There muscles in upper limbs, and arreflexia. He had were no changes in heart rate during these a spastic paraparesis, with brisk jerks and events. A combination of respiratory and bilateral extensor plantar responses. Deep cardiovascular mechanisms might have sensation was impaired in both hands, and been responsible for the severe complica- there was an area of dissociated sensory loss tions described. from the face down to T5 bilaterally. An MRI showed atrophy of the right cer- ebellar hemisphere and a cervical syrinx extending upwards to the lower part of the medulla (fig 1). He denied any sleep difficul- Respiratory abnormalities have been described ties. in patients with syringomyelia and syringo- He had posterior fossa decompression with http://jnnp.bmj.com/ bulbia.'-' Several nuclei and pathways known laminectomy at C1 and C2 in June 1988, and to be involved in the voluntary or automatic an extensive cervical arachnoiditis was found. regulation of breathing in animals may even- The floor of the fourth ventricle was also tually be damaged by a syrinx, such as the explored, and a syringocysternal catheter was vagal afferent fibres from the lungs to the placed. After operation his swallowing difficul- medulla; the nucleus tractus solitarius;6 the ties worsened and the left upper limb became inspiratory and expiratory neurons located at weaker. Nine after days surgery the patient had on September 27, 2021 by guest. Protected copyright. the motor dorsal vagus, ambiguus, and tractus a sudden cardiorespiratory arrest while asleep solitarius nuclei7; the ascending afferents and in hospital and was successfully resuscitated. Instituto de Investigaciones descending efferents involved in breathing He received intermittent positive pressure ven- Neurol6gicas Dr Rasil control at the medulla or cervical spinal cord; Carrea, FLENI, and the effector motor neurons to the dia- Buenos Aires, Argentina phragm and intercostal muscles.8 Despite the Martin A Nogues recognition of respiratory hazards in syringo- Horacio Encabo myelia-syringobulbia patients, breathing Hospital de Clinicas abnormalities have so far received scant atten- Jos6 de San Martin, tion, particularly regarding their potential Facultad de Medicina, Universidad de implication in sudden death. Buenos Aires, Buenos The integrity of pathways and centres Aires, Argentina involved in voluntary and automatic breathing Ricardo Gene may be assessed by functional volume and Correspondence to: Dr Nogues, Instituto de pressure studies, together with polygraphic Investigaciones Neurol6gicas recordings during sleep. We describe the clin- Dr Raul Carrea, FLENI, ical and laboratory findings in three patients Ayacucho 2166, (1112) 4000 80.00 Buenos Aires, Argentina with advanced syringomyelia and syringobul- Pet C2 (mm Hg). Received 9 May 1991 bia. Respiratory and polysomnographic studies and in revised form Ventilatory response to CO2 rebreathing: ventilation/PCO2 13 August 1991. disclosing abnormalities may explain the curve slopes in the three patients. Mean response in Accepted 21 August 1991 severe acute complications reported. normal subjects given in open circles. 586 Nogues, Gene, Encabo tilation for a month. He was found dead one syringoperitoneal shunt. Postoperatively, he J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.7.585 on 1 July 1992. Downloaded from morning three months after surgery. recovered gradually, with some improvement of the spastic tone. Case 2 On examination the patient had bilateral This 68 year old man developed wasting and Horner's syndrome and considerable nystag- weakness of both hands at the age of 30. This mus in all directions. There was weakness of was followed by progressive loss of pain and the muscles innervated by the IXth, Xth, and temperature sensation over the right upper XIth cranial nerves. Both upper limbs and limb, and later the left, in a cape distribution shoulder girdles showed definite muscle wast- down to the waist. Over the past 10 years he ing with reduced muscle tone and claw-like developed progressive weakness of the lower deformities of both hands. His upper limbs limbs, severe oscillopsia, dysphagia, and occa- were areflexic. There was severe bilateral spas- sional dyspnoea. The diagnosis of syringomye- ticity with hyperreflexia of the lower limbs, lia was confirmed by myelography. Born by ankle clonus, and bilateral extensor plantar normal delivery, he had suffered meningitis at responses. Sensory testing disclosed an appre- the age of 11. ciable dissociated loss, mainly in a right hemi- On examination in August 1986 the patient cape distribution. Overall, he was severely had a short neck and low hair implantation. disabled with hardly any useful function of his There was a left Horner's syndrome, marked hands and he could walk only with assis- rotatory nystagmus to the left, wasting of the tance. left sternocleidomastoid muscle, and wasting Over the past two years he had had occa- and fasciculations ofthe left side of the tongue. sional respiratory difficulties at night, waking There was noticeable bilateral wasting and up suddenly with breathlessness. Relatives weakness of proximal and distal upper limb were well aware of these episodes, which were muscles, and reflexes were absent. He had worse after heavy meals or alcohol intake. They spastic paraparesis, and bilateral extensor plan- turned him over and woke him up. In Novem- tar responses were elicited. Dissociated senso- ber 1988 the patient went to sleep after a large ry loss down to T4 was found. Vibration sense meal, waking up with shortness of breath. He was impaired in all four limbs, but position sat up in bed, recovered within a few minutes, sense was normal throughout. Although he fell asleep again, and was found dead one hour never complained of sleep-wake difficulties, later. over the past 10 years relatives had noticed irregular breathing during sleep, such as respi- Pulmonary function tests ratory pauses followed by strenuous snoring. The following variables were determined: flow- In December 1988, the patient's wife reported volume curves using a Fleisch pneumotach; he had stopped breathing altogether in the forced vital capacity (FVC); forced expiratory course of an afternoon nap, and became volume at one second (FEV1); FEV,/FVC cyanotic. She aroused him violently and star- ratio; flow expiratory peak; and instantaneous ted cardiopulmonary resuscitation. After sev- flows at 25%, 50%, and 75% FVC. Expiratory eral minutes he began to breathe normally, muscle endurance was estimated from the showing a decerebrate posture for several more values of maximal voluntary ventilation during minutes. He was admitted to hospital and 12 seconds. Respiratory muscle force was http://jnnp.bmj.com/ recovered fully. The patient refused to be estimated from maximal inspiratory buccal investigated by MRI. pressure (PiMax) measured at total lung capacity and maximal expiratory buccal pres- Case 3 sure (PeMax) measured from residual volume. This 38 year old man first noticed progressive Values obtained were compared with normal wasting and weakness of both arms at the age control values from our own laboratory.9 of 25. A year later his legs were also weak and Arterial blood gases were determined from a walking had become difficult. His medical sample obtained by brachial puncture while on September 27, 2021 by guest. Protected copyright. history was unremarkable apart from his birth the patients were breathing room air. Respira- after a prolonged and traumatic labour. tory centre output was then evaluated by In 1975 a myelogram showed widening of means of the response to CO2 rebreathing, the cervical and thoracic spinal cord. A CT with a Collins spirometer containing a volume scan showed moderate hydrocephalus with equal to the subject's vital capacity plus one considerable dilatation of the fourth