J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.51.8.1106 on 1 August 1988. Downloaded from

1106 Letters nerve, mixed median nerve and mixed ulnar before treatment but a P45 was seen clearly Peripheral Neuropathy 3rd ed. Philadelphia: nerve potentials were 24, 23 and 38 pV at 54 ms, after therapy. WB Saunders, 1984:1925-6. respectively. Following 9 months treatment This patient presented subacutely with the 5 Gilliatt RW, Goodman HV, Willison RE. The they were 19, 25 and 38 pV respectively. The signs and symptoms of spinal cord disease recording of lateral popliteal nerve action minimum F response latency (median nerve due to Vitamin B12 deficiency. The subacute potentials in man. J Neurol Neurosurg stimulation) and the triceps surae Psychiatry 1961;24:305-1 8. H presentation may have been precipitated by 6 Cox-Klazinga M, Endtz U. Peripheral nerve response latency (popliteal fossa stimu- the coincident metabolic stress of surgery8 or involvement in pernicious anaemia. J Neurol lation) were normal before treatment (26-2 by the nitrous oxide anaesthesia.9 In addi- Sci 1980;45:367-71. ms, 32-4 ms respectively) and did not change tion to the clinical evidence, she had electro- 7 Fine EJ, Hallett M. Neurophysiologic study of significantly after treatment (25-5, 30-8 ms physiological evidence of spinal cord subacute combined degeneration. J Neurol respectively). dysfunction which has been documented Sci 1980;45:331-6. Somatosensory cortical responses, previously in three patients.7 Two of these 8 Amess JAL, Burman JF, Murphy MF, Paxton AM, Mollin DIL. Severe marrow referred to Fz, were recorded from 2 5 cm three cases were and elderly had absent sural change associated with unsuspected mild behind the vertex following posterior tibial nerve action potentials which may have Vitamin B12 deficiency. Clin Lab Haematol nerve stimulation at the ankle, and from a affected the latency of their cortical 198 1;3:231-7. point just posterior to C3 and C4 on the responses. The patient reported here was 9 Schilling RF. Is nitrous oxide a dangerous ana- 10-20 system, following median nerve stimu- elderly but had normal peripheral nerve sen- esthetic for Vitamin B12 deficient subjects? lation at the wrist. Erbs point and spinal (C2 sory and mixed nerve action potentials. Thus JAMA 1986;255:1605-6. spine) recordings were also made but are not the cortical delay demonstrated in the 10 McCleod JG, Walsh JC, Little JM. Sural nerve fig Med J shown. Stimuli sufficient to cause a small must be due to some pathological process biopsy. Aus 1969;2:1092-6. muscle twitch were delivered at 3 1 rostral to the dorsal root Hz and ganglion, perhaps Accepted 2 April 1988 two runs of 256 trials were averaged. The rostral to the dorsal root as the H responses N20, P25 and P40 components of the SSEP were within normal limits. Although some from right median nerve stimulation, before delay remained after 9 months' therapy (fig and after treatment, are shown in the fig. b), a definite improvement has been Before treatment the peak latencies were recorded. This conclusion concurs with the approximately 25, 35 and 56 ms respectively. neuropathological data which suggest that Polyneuropathy cranialis following cervicalProtected by copyright. After treatment these latencies fell to 22 5, the initial neurological abnormality in epidural anaesthesia 312 and 48 ms respectively. In addition to Vitamin B12 deficiency is a myelopathy.1 I shorter latencies, the entire waveform was Although the delayed arrival of Sir: Epidural anaesthesia is a relatively safe somato- and better synchronised after treatment. Erb's sensory information at the cortex suggests a useful method of pain control but com- point potentials were normal (latencies to process and a plications may infrequently arise. Most of demyelinating similar delay the peak, 10-2 ms before, 9 9 ms after treat- has been demonstrated in the nerves of the reported neurological complications of or ment). The cervical potentials were poorly lower limb once Vitamin B12 deficiency has epidural spinal anaesthesia primarily affect the lower defined and could not reliably be measured. become established,2 6 this may be due to a extremities.1 Paraplegia may Following right posterior tibial nerve stimu- selective fallout oflarge diameter myelinated result from spinal cord ischaemia due to lation no cortical event could be discerned nerves, as is seen in the peripheral nervous arterial hypotension during surgery or com- system. promise of blood supply to the cord by the or condition of the or i)0 JPR DICK procedure patient, by J~~~~~2pV the of an or subdural I-lo JC SMAJE production epidural P CRAWFORD haematoma.2 Direct injury to the spinal RJ MEARA cord or the nerve roots has also occurred DI SHEPHERD following inadvertant subarachnoid admin- Departments of Neurology, and istration oftoxic chemicals, or chemical con-

Neurophysiology, tamination of anaesthetic solution.2 Cranialhttp://jnnp.bmj.com/ North Manchester General Hospital, nerve palsies are rare. Unilateral trigeminal DeLaunays Road, nerve palsy has been reported after lumbar Crumpsall, Manchester M8 6RB, UK epidural anaesthesia; the proposed mech- anism being an ascending local anaesthetic effect.3 References Hypoacousis, after spinal anaesthesia, has also been reported and it was postulated evoked Fig Somatosensory potentials I Pant S, Asbury AK, Richardson EP. The that a decrease in cerebrospinal fluid pres-

(referred to Fz) from just posterior to C3 myelopathy of pernicious anaemia: a neuro- sure produced a distortion of the structures on September 25, 2021 by guest. following right median nerve stimulation at pathological reappraisal. Acta Neurol Scand of the inner by pressure imbalance, the wrist in a 73 year oldfemale with 1968;44:Suppl 35, 1-36. resulting in a dampening of the response to pernicious anaemia before (A) and after 2 Pallis CA, Lewis PD. The Neurology ofGastro- auditory stimuli.4 I (There is a free commu- (B) 9 months' Vitamin B12 therapy. intestinal Disease. London: WB Saunders, across 1974:34-41. nication the cochlear aqueduct Consecutive runs of 256 trials have been between the fluid and the 3 Shorvon S, Carney MWP, Chanarin 1, Rey- cerebrospinal peri- averaged on each occasion. The latencies of nolds EH. The neuropsychiatry of megalo- lymph of the cochlear apparatus, thus the N20, P25 and P40 are 25, 35 and 56 ms blastic anaemia. Br Med J 1980;281:1036-8. changes in cerebrospinal fluid pressure are respectively before treatment and 22 5, 31 2 4 Victor M. Vitamin B12 Neuropathy. In: Dyck accompanied by changes in cochlear peri- and 48 ms respectively after treatment. PJ, Thomas PK, Lambert EH, Bunge R, eds. lymph pressure). J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.51.8.1106 on 1 August 1988. Downloaded from

Letters 1107 However, Hardy reported acute hypo- ition whilst being mechanically ventilated. trophic lateral sclerosis-dementia complex acousis in three patients at the end of injec- Intrathecal injection would have probably and myokymia. tion of local anaesthetic solution in the resulted in more profound neurological dys- A 62 year old man presented with a 4 lumbar extradural space and postulated that function, involving the upper and possibly month history of progressive dysarthria, the hypoacousis in his cases was a con- the lower limbs. Epidural injection would confusion, muscle cramps, and fatigue. He sequence of the increase in pres- have been unlikely to result in lower cranial was moderately demented. Prominent slow sure which accompanied the increase in nerve palsies because these nerves exit rippling movements (myokymia) were evi- cerebrospinal fluid pressure.6 through the dura which is attached to the dent diffusely, but were most prominent in We report an unusual case of reversible base of the . the muscles of his lower extremities. These bilateral abducens nerve, right facial nerve The occurrence of cranial nerve palsies movements persisted during sleep. There and bilateral vestibulocochlear nerve palsies following cervical epidural anaesthesia is an was mild, symmetric muscle weakness and following epidural anaesthesia. A 65 year uncommon complication of this form of wasting that was worse in the lower old woman who had been having regular anaesthesia which fortunately is of benign extremities. Muscle relaxation was normal. haemodialysis for chronic renal failure for nature with a favourable outcome, provid- Deep tendon reflexes were symmetrically many years was referred for management of ing reassurance to both the attending clin- brisk, and Babinski's sign was present intractable and increasingly severe pain in ician and patient. The timing of the onset of bilaterally. Snout, glabellar, grasp, and her neck and hands. Neurological exam- symptoms from anaesthesia should allow palmomental reflexes were prominent. The ination and upper limb electromyographic differentiation of the underlying patho- following were normal: thyroid function studies were normal. Epidural block was genesis into either a mechanical effect of tests; serum protein electrophoresis; cere- performed through an indwelling catheter at injection or a local anaesthetic effect on brospinal fluid studies; head CT scan with the C6-7 level. Marcain, 8 mls of 0 25% nerve roots. and without contrast; EEG; urinary lead, solution, was injected through this catheter GRAEME J HANKEY mercury, and arsenic determinations from a together with 40 mgs (1 ml) Depo-Medrol. Department of Neurology 24 hour collection; motor and sensory nerve The patient was placed in a head-down posi- DAVID PERLMAN conduction velocities, distal sensory laten- tion and her blood pressure remained con- Department ofAnaesthesia, cies, and amplitude of evoked motor unit stant at 100/60 mm Hg. After 5 minutes she Royal Perth Hospital, potentials. EMG showed abnormally became dyspnoeic due to ventilatory failure. Perth 6001, Australia increased insertional positive waves and con- Protected by copyright. She was mechanically ventilated with 100% References tinuous muscle fibre activity at rest. Most of oxygen via a bag and mask for 30 minutes. the motor unit potentials appeared normal She was then able to breath spontaneously I Dawkins CJM. An analysis of the compli- in form, but some were polyphasic and some but complained of deafness. Neurological cations of extradural and caudal block. Ana- were of increased amplitude. There were examination revealed bilateral abducens esthesia 1969;24:554-63. some rhythmic repetitive bursts of nerve palsies, right lower motor neuron 2 Kane RE. Neurologic deficits following epi- normal-appearing, rapidly-firing motor facial nerve palsy and bilateral ves- dural or spinal anaesthesia. Anesth Anaig units (myokymic discharges), as well as tibulocochlear nerve palsies. The remainder 1981 ;60: 150-6 1. occasional positive sharp waves and of the neurological examination was nor- 3 Shigematsu T, Wang H, Nagano M. Trigem- inal nerve palsy after lumbar epidural anes- fibrillations. An ulnar nerve block at the mal. The patient was observed and managed thesia. Anesth Anaig 1985;64:646-53. elbow did not abolish the continuous muscle conservatively. After 3 hours her lower cra- 4 Gordan AG. Hypoacousis after spinal ana- activity in the first dorsal interosseous nial nerve palsies had completely resolved. esthesia. Lancet 1983;ii:793. muscle. Carbamazepine produced no The absence of long tract signs in this case 5 Panning B, Mehler D, Lehnhardt E. Transient apparent change in the spontaneous move- indicated that the integrity of the spinal cord lower frequency hypoacousia after spinal an- ments. was preserved. It is considered that the ini- aesthesia. Lancet 1983;ii:582. The patient continued to deteriorate, and tial mechanical ventilatory failure was due 6 Hardy PAJ. Hypoacousis following extradural injection. Br J Anaesth 1985;57:573. 9 months after the onset of symptoms, he to anaesthesia of the C3, 4, 5 nerve roots 7 Burn JM, Guyer PB, Langdon L. The spread of developed pneumonia and died. The neuro- that constitute the phrenic nerve, resulting solution injected into the epidural space, a pathology was consistent with amyotrophic http://jnnp.bmj.com/ in diaphragmatic paralysis. As study using epidurograms in patients with lateral sclerosis-dementia complex.2 There diaphragmatic function returned it was the lumbosciatic syndrome. Br J Anaesth was loss of neurons and reactive astrocytosis noted that the abducens nerves and ves- 1973;45:338. in the motor cortex, the motor fifth and tibulocochlear nerves were involved bilater- twelfth cranial nerve nuclei, and the ventral ally in addition to the right facial nerve at horns ofthe spinal cord. Spinal cord sections the nuclear or infranuclear level. The com- Accepted 2 April 1988 showed degeneration of the corticospinal plete return to normal function of these tracts. Skeletal muscle sections showed nerves after 3 hours (the expected duration grouped fibre atrophy. There were rare of action of Marcain) was most consistent Myokymia in motor neuron disease senile plaques in the cortex, but no neuro- on September 25, 2021 by guest. with an ascending local anaesthetic effect of fibrillary tangles. the Marcain on the upper cervical nerve Sir: In motor neuron disease, spontaneous Generalised myokymia is rare. When roots and lower cranial nerves.7 It is sus- motor unit discharges tend to be isolated seen, it almost always reflects a diffuse injury pected that the Marcain solution was injec- (fasciculations), rather than continuous or hyperirritability of peripheral nerves as ted into the extra-arachnoid/subdural space muscle fibre activity or repetitive bursts can be seen in association with toxins,3 and transfer of this medication in a cranial (myokymia). Occasionally, grouped dis- thyrotoxicosis,4 Guillain-Barre syndrome,5 direction was facilitated by gravity as the charges and doublets are seen in such and polyneuropathy.6 This concept is patient had been placed in a head-down pos- patients.' We report a patient with amyo- supported by several lines of evidence.5`7