Last year we took a close look at the consequences of a hypothermic cardiac arrest. Whilst small numbers emerge unharmed, fatalities are common and many of those who survive are left with permanent disabilities. Following that post we came across a rather unique study that reported on the long term findings of a young woman who endured an extraordinary episode of hypothermia. Here's what they found...
"In May 1999, a 29 year old female junior doctor fell through a frozen river waterfall gully when skiing. She became trapped in the ice-cold water with her head submerged in the water and her skis on the surface of the frozen river. Her friends tried in vain to pull her out with a rope tied around her left ankle. She stopped moving after 40 minutes. She was eventually pulled out of the water through a hole which was cut in the ice after 80 minutes. She was found to be clinically dead, and resuscitation was immediately started. On admission to hospital, approximately 2 hours later, she was connected to a cardiopulmonary bypass machine and slowly warmed. Her lowest rectal temperature measured at the hospital was 13.7 C (56.7 F), which to our knowledge is the lowest temperature reported in a surviving patient. She had cardiac arrest for approximately 3 hours and developed multi-organ failure.
All sedation was stopped after 2 weeks, and she mentally made a full recovery. However, she had almost complete paralysis in both arms and legs with weak proximal movements. Her EEG was normal, and an MRI of the brain showed only minimal frontal white matter abnormalities. She required respiratory assistance for the next 35 days. Her physical condition gradually improved. After 4 months she had regained some strength in her trunk and proximal muscles of both arms and legs. However, the distal muscles, especially in the arms (thenar, hypothenar, intrinsic hand muscles, wrist extensors and flexors) were very weak with symmetrical atrophy.
Atrophy of the thenar eminence still visible 11 years after the incident
She could walk without aid, but had a bilateral drop-foot which was most pronounced on the left side. Stretch reflexes were absent. She had considerably reduced touch and pressure sensibility distally in the upper limbs and to a much lesser degree in her feet. Pain and temperature sensibility were almost normal. She was able to ski 6 months after the accident but she had to tape her hands to the ski poles. Her skiing boots gave her excellent stability, but she had great difficulty putting them on.
In June 2000 there was still pronounced atrophy and weakness of hand and distal arm muscles, but in the lower limbs there was only a slight drop-foot on the left side. She complained of cold intolerance and had hyperaesthesia to light touch distally in both arms and legs (a feeling of ‘‘sparkling water running down the skin’’). Stretch reflexes were now present, but reduced. She started to work again part time from January 2001 and full-time from February 2002. She had, however, had to change medical specialty from surgery to radiology because the strength of her hand grip and wrist extension/flexion was still severely reduced. Three years after the accident the strength of her hand grip had improved. In the following years she has felt progressively stronger, but clinical neurological findings have been almost unchanged. There remains a clear difference between findings in the upper and lower limbs and as there is still severe muscle atrophy of the hand muscles. She is now very active in sports but complains of reduced endurance and reduced capacity to withstand cold temperatures, especially in her hands..."
What was the cause of this long standing neurological deficit?
Critical Illness Polyneuropathy (CIP) is a common complication of life threatening illnesses. Typically, it is seen in up to 70% of those who spend 7 or more days on an intensive care unit. Patients tend to develop flaccid, symmetrical paralysis of their trunk and limbs. Often, patients need several weeks of mechanical ventilation before their respiratory muscles can work independently. Motor and sensory changes in the limbs often take longer to recover and in some cases permanent disabilities can occur.
Critical Illness Polyneuropathy (CIP) is normally symmetric and predominantly affects the lower limbs. Cranial nerves are often spared. Prolonged bed rest, infection and poor glycaemic control are amongst the leading independent risk factors for CIP. A comprehensive review can be found here
In CIP the amplitude of action potentials in both motor and sensory nerves are reduced whilst nerve conduction velocity is often maintained. This reflects damage to the nerve and preservation of the surrounding myelin sheath. However in severe cases of CIP both the nerve and myelin sheath can be damaged. This was certainly the case in our hypothermic victim and much of the clinical picture fits with a diagnosis of CIP. However there are several factors that go against this diagnosis. Unlike the widespread damage seen in CIP, nerve damage in this patient was patchy. In the lower limbs, the tibial nerves were completely spared, whilst others like the common peroneal nerves were damaged and recovered slowly. Meanwhile in the upper limbs, nerve studies revealed more extensive damage and now a decade on recovery is far from complete. Rather than CIP, the authors believe that this is the direct result of hypothermia. The patient was trapped head down in freezing water for 80 minutes. Her head, trunk and upper limbs were likely to have undergone the greatest fall in temperature. Her lower limbs were clear of the water and may have been relatively spared. This would explain why, the upper limbs were most affected and that despite damage to peripheral nerves in the lower limbs, the deep nerves were preserved. According to the authors, any differences in neurological injury between the lower limbs could be explained by the trauma sustained to the left foot following efforts to pull the victim out.
A hypothermic cardiac arrest can have a devastating impact upon the victim. For those who survive, complications can be far reaching and result in life changing disabilities. Those of us involved in mountain medicine need to recognise this and educate others about the consequences of such an overwhelming event.
If you would like to find out more about mountain medicine why not join the British Mountain Medicine Society? See this link for details.