Eur Arch Psychiatry Clin Neurosci (1992) 241 : 205-209 Archives of and Psychiatry Clinical Neuroscience 9 Springer-Verlag 1992 Anterior Spinal Artery Syndrome of the Cervical Hemicord Ralf W. Baumgartner and Walter Waespe Department of Neurology, University Hospital, Zt~rich, Switzerland Received July 12, 1991 Summary. Three patients developed signs of a unilateral cervical cord lesion 6 to 36 h after the acute onset of severe cervico-brachial pain. The neurological deficit progressed over 6 to 18 h. On the painful side a central Horner's syndrome, a hemiparesis with plegia of the hand, and a slight pallhypaesthesia were found. On the opposite side thermhypaesthesia and hypalgesia were noted with a level at the dermatome C5 or C6. T2-weighted MR images revealed in one patient a small area of increased signal intensity restricted to one half of the cervical cord, and electromyography in another patient showed after 6 months evidence of segmental chronic denervation. Both abnormalities were found at the clinically expected level. The findings are consistent with a small infarction of the cervical cord in the perfusion territory of a central (sulco-commissural) artery, a duplicated anterior spinal artery or an anterior spinal branch of the vertebral artery. Key words: Spinal cord - Ischaemic infarction - Anterior spinal artery syndrome. Introduction The anterior spinal artery syndrome (ASAS) was first described by Spiller [33] in 1909. It is a well-defined clinical entity due to bilateral infarction in the perfusion territory of the anterior spinal artery (ASA) [12, 20, 24, 33]. Spinal cord infarctions restricted to a unilateral perfusion territory of the ASA have very rarely been described to our knowledge [7, 15]. We therefore report and discuss the clinical, radiological, electrophysiological and laboratory findings of three patients, whose symptomatology is assumed to result from an infarction in the perfusion territory of a central (sulco-commissural) artery, a paired cervical ASA or an anterior spinal branch of the vertebral artery. Case Reports The main clinical, and all radiological, Doppler, electrocardiographic, CSF and blood examination findings in the three patients are summarized in Table 1. Patient 1 A 54-year-old healthy man suddenly experienced severe pain in the neck with diffuse irradiation to his right arm. Pain disappeared after 3 h to return the next morning. After 36 h he noticed weakness in his right extremities progressing within 6 h to plegia of the hand and inability to walk. Medical history was unremarkable - as in the other two patients to be reported - for cervical trauma, chiropractic manipulation, vertebral angiography, drug abuse, smoking, hypertension, diabetes mellitus, dyslipidaemia, syphilis, or collagen-vascular disease. General physical examination was normal including movements of the diaphragm. Neurological examination disclosed on his right side a central (pharmacologically tested) Horner's syndrome and a flaccid hemiparesis affecting especially the hand with an extensor plantar response. On the left side hypalgesia, thermhypaesthesia and a slight hypaesthesia with an upper level at the dermatome C5 were noted. Cervical MRI (1,5 Tesla; spin echo: repetition time 1700 ms, echo time lOOms) showed a small area of increased signal intensity restricted to the right half of the spinal cord at the C5 vertebra (Fig. 1). 8 months later, the residual signs were a slight spastic hemiparesis affecting especially the distal parts of the upper extremity (armparesis grade 4-5 without muscle atrophy, and ability to walk without mechanical aids) and miosis on the right side, whereas contralaterally the dissociated sensible deficit remained essentially unchanged. Patient 2 While driving his car and moving his head to the left this healthy 52-year-old man suddenly felt excruciating pain in the neck irradiating to his left ulnar forearm. After 6 h he developed left-sided hemiparesis which progressed over 24 h. General physical examination was normal. Neurological examination revealed on the left side a central (pharmacologically tested) Horner's syndrome, a flaccid hemiparesis affecting especially the hand with an extensor plantar response and a slight pallhypaesthesia. On the contralateral side there was hypalgesia and thermhypaesthesia with an upper level at the dermatome C6. On the seventh hospital day the patient suddenly veto- 206 Table 1. Summary of the findings in patients 1-3 Patient 1 2 3 Sex Age (years) Initial symptom Neurological deficit: Latency (h) Progression over (h) Homer's syndrome Motor hemiparesis Hemipallhypaesthesia Diss. hemis, deficit" Cervical myelogram Cervical MRI Brain CT Brain MRI EMG Doppler sonography Electrocardiogram CSFe Bloods Male 54 Pain neck and right arm Male 52 Pain neck and left arm Female 62 Pain right shoulder 36 6 Right Right No Left (C5) No Right hyperintensity No No Nd No No No No 6 24 Left Left Left Right (C6) Nd No Nd PICA-inf. Nob No No No No 12 10 Right Right Right Left (C5) No No No Nd Pa ~ No d No No No a = dissociated hemisensory deficit with the upper level in parentheses b = needle myography of deltoid, biceps, triceps and abductor digiti quinti muscles c = pathologic (signs of chronic denervation in the deltoid muscle) d = this patient showed haemodynamically insignificant plaques at both carotid bifurcations e = CSF examinations included oligoclonal banding, determination of antibody titres against Borrelia burgdorferi, several viruses including the herpes group ant ri- - ~ le post Fig. 1. Axial T2-weighted magnetic resonance images at the C5 vertebra in patient 1 (1,5 Tesla; spin echo: repetition time 1700 ms, echo time 100ms; slice thickness 6mm). For further explanation see text = Blood examinations included complete white cell and red cell counts, platelet count, Westergren sedimentation rate, glucose, cholesterol, protein electro- and immunoelectrophoresis, activated partial thromboplastin time, prothrombin and thrombin time, fibrinogen, antinuclear and anti-DNA titres, anticardiolipin antibodies, TPHA and VDRL tests, antibody titres against Borrelia burgdorferi, several viruses including the herpes group Nd = not done; No = normal minogen activator. T h e spontaneous nystagmus disappeared within 3 days. 6 months later the H o r n e t ' s syndrome and pallhypaesthesia had disappeared and the hemiparesis had improved (distally accentuated arm paresis grade 4 - 5 , walking without mechanical aids). The contralateral dissociated sensory hemisyndrome remained essentially unchanged. Needle electromyography of the deltoid, triceps, biceps and abductor digiti quinti muscles showed a slightly reduced interference pattern. Patient 3 ited and complained of severe vertigo. Neurological examination disclosed a spontaneous horizontal nystagmus beating to the left side which increased in intensity in left gaze positions. Cerebral M R I (1,5 Tesla; spin echo: repetition time 2000ms, echo time 100ms) on the same day showed hyperintense areas in the cerebellar perfusion territory of the left P I C A , i.e. ipsilateral to the paresis. A n echocardiogram disclosed an atrial septal aneurysm without interatrial shunting. Investigations for coagulopathy showed a slightly diminished fibrinolytic activity due to an impaired mobilisation of tissue plas- This 62-year-old healthy woman experienced sudden pain and paraesthesias in her right shoulder. Twelve hours later ipsilateral paraesthesias in all fingers and the whole leg and a hemiparesis reaching its m a x i m u m within 10 h were added. H e r medical history was remarkable only for intermittent cervical pain of 5 years duration. Neurological examination revealed on the right side a flaccid hemiparesis of the extremities with plegia of the hand, a slight pallhypaesthesia, a central (pharmacologically tested) H o m e r ' s syndrome and a thermographic brachiofacial a s y m m e t r y with hyperthermia on the right side (right: forehead +0.3~ cheek +1,0~ lower jaw +0.2~ 207 upper arm +1.6~ forearm +1.5~ hand +0.2~ A ninhydrin test showed a hypohidrosis of the right palm. Contralaterally hypalgesia and thermhypaesthesia were noted with an upper level at the dermatome C5. Fluoroscopic examination demonstrated normal movements of the diaphragm. Nine days after clinical onset electrical stimulation of the median, ulnar and radial nerves showed normal excitability of the right hand and forearm muscles. Magnetic stimulation of the motor cortex (Magstim 200, Novametrix Medical Systems, England) and electrical stimulation at C7/T1- and T12FLl-interspace (Digitimer 180, Digitimer Ltd, Hertfordshire, England) with bilateral recording (surface electrodes) over the belly and tendons of abductor digiti minimi, biceps brachii and anterior tibial muscles respectively were performed. On the paretic right side no muscle potentials could be elicited with magnetic stimulation, whereas the electrically elicited potentials showed latencies and amplitudes within normal limits. On the left side central motor conduction times and the amplitude of the compound motor action potentials were normal. Somatosensory evoked potentials elicited by stimulation of both median nerves at the wrist and recorded from Erb's point, from the cervical spine at C6 and from the scalp were normal. 6 months later there was still a slight spastic hemiparesis on the right side more marked on the distal portions of the upper extremity (armparesis grade 4-5, walking without mechanical aids). The dissociated hemisyndrome on the contralateral side remained essentially unchanged. Needle electromyography of the right deltoid muscle showed an increased mean duration (+52%) and incidence of polyphasia (+20%) in 20 analysed motor unit action potentials (MUAP). The interference pattern was only slightly reduced and the MUAP amplitudes were normal. Electromyography of the right deltoid, triceps, biceps and abductor digiti quinti muscles showed only a slightly reduced interference pattern. Discussion We describe three patients who presented with a uniform neurological deficit that developed 6-36 h after the sudden onset of excruciating unilateral cervico-brachial pain and progressed over 6-18 h. The clinical symptomatology was characterised on the painful side by a central Homer's syndrome, a flaccid hemiparesis with plegia of the hand and unability to stand without assistance, and a slight pallhypaesthesia. On the contralateral side there was a hypalgesia and thermhypaesthesia with an upper level at the dermatome C5 or C6. On the painful side no segmental hyper- or hypaesthesia were noted. Motor function was normal in the neck as were the movements of the diaphragm. T2-weighted cervical MR images were abnormal in patient 1, disclosing a small area of increased signal intensity within one half of the spinal cord. This abnormality was localised ipsilateral to the hemiparesis and at the clinically expected level. All radiological examinations of the brain were normal except in patient 2 (to be discussed). Extensive electrophysiological examinations in patient 3 strongly suggest that her hemiparesis was caused by a lesion of the cortico-spinal tract. Followup needle electromyography showed only in this patient's deltoid muscle evidence of chronic denervation suggesting segmental damage of anterior horn cells and/or of motor root fibres. All the clinical, radiological and electrophysiological findings point to a lesion in the anterolateral cervical hemicord with a rather small vertical extent. These and the normal CSF and blood findings as well as the benign clinical outcome argue against an inflammatory, neoplastic or haemorrhagic process or a vascular malformation. Venous spinal cord infarctions show a different clinical picture owing to bilateral involvement of the cord [30, 41]. Taking into consideration that the clinical course resembles that of an ASAS, it is assumed that all these patients suffered from an arterial infarction in the perfusion territory of the cervical ASA. In support of the vascular origin is the subsequent occurrence of a MRI-verified PICA-infarction ipsilateral to the cervical lesion in patient 2. Because an ASAS is known to result in a bilateral infarction, the question arises as to which alterations in the blood supply of the cervical cord could cause unilateral infarction. At a certain stage of human embryonic development the arterial vasculature of the spinal cord is based on longitudinal anastomotic channels and their penetrating vessels [20]. Later, the two primitive anterior longitudinal anastomotic channels (ALAC) migrate medially and fuse to form the ASA. As the two ALAC's often do not merge completely, the ASA may be duplicated for short distances [38]. The central arteries derive from the anterior penetrating vessels and therefore supply only the half of the cord from which they originate [38], Moreover in about 10% of humans the union of the anterior spinal branches of the vertebral artery is delayed as far down as the lower cervical region [20]. Therefore ischaemia in the perfusion territory of a central artery, or a duplicated ASA, or an anterior spinal branch of the vertebral artery could provoke an unilateral infarction. This assumption is in accord with the patient of Decroix [7] who showed a Brown-S6quard syndrome due to a pathologically verified infarction of the spinal hemicord. We did not perform spinal angiography because this would not have benefited the patients, although it would probably have provided confirmatory data for our assumption. It is important to note that all the patients showed a central Homer's syndrome due to a lesion of the central sympathetic pathway on the hemiparetic side. This pathway descends in the cervical cord between the lateral spino-thalamic and cortico-spinal tracts [32], a region irrigated by the ASA [20, 38]. In contrast to our patients we found no description of a Homer's syndrome in a literature survey of 45 cases with a cervical ASAS [2-6, 9-11, 13, 14, 16-19, 21-23, 25-27, 29, 31, 33-37, 40, 41]. As the signs of a central Homer's syndrome are often discrete [32] and are expected to occur bilaterally in ASAS, they may easily be overlooked. However, in the two patients with pathologically verified unilateral infarction of the cervical cord an ipsilateral Homer's syndrome was described [7, 15]. The hemiparesis is caused by interruption of the cortico-spinal tract between the C4 to C6 level. The arm is most strongly affected, because its 208 u p p e r m o t o r n e u r o n fibres run medially in the corticospinal tract and are therefore closer to the core of the perfusion territory of the A S A than the c o r r e s p o n d i n g fibres o f the leg. T h e contralateral dissociated hemisensory deficit results f r o m interruption of the crossed fibres ascending in the spino-thalamic tract. The slight hemipallhypaesthesia on the paretic side is explained by interruption of pallaesthetic fibres, s o m e of which are r e p o r t e d to ascent in the medial part of the lateral c o l u m n [28]. Infarction in the cervical perfusion territory o f the A S A has b e e n d o c u m e n t e d in a variety of conditions: fibrocartilagineous e m b o l i s m [4, 17, 19, 22, 23, 27, 34], A S A thrombosis [16], occlusion of the vertebral artery [29], syphilis [33], cocaine-abuse [26], caisson-disease [6], t r a u m a [29], a n g i o g r a p h y of the vertebral artery [6, 9, 11, 18, 25, 36], H a r r i n g t o n rod i n s t r u m e n t a t i o n [39] and intrathecal p h e n o l injection [39]. H o w e v e r , in m a n y cases the aetiology r e m a i n e d u n k n o w n [3, 5, 10, 11, 14, 21, 29, 31, 35, 40, 41]. I n spite of extensive examinations the aetiology of the suspected unilateral, cervical infarction could not be d e t e r m i n e d in patients 1 and 3. In patient 2 the infarction in the territory of the ipsilateral P I C A is in favour of arterio-arterial emboli originating in the left vertebral artery, but D o p p l e r s o n o g r a p h y of the subclavian, extra- and intracranial vertebral arteries was normal. Cardiac e m b o l i s m f r o m his atrial septal aneurysm is possible, but the f r e q u e n c y of cerebral emboli in this condition is disputed [1, 8]. Finally the possibility of p r i m a r y a t h e r o t h r o m b o s e s due to the decreased fibrinolytic activity of his s e r u m c a n n o t be ruled out. T o summarize, we suggest that in patients presenting with rapidly evolving neurological signs which are prec e e d e d by severe cervico-brachial pain and which point to an unilateral lesion of the cervical cord, a progressive stroke of the cervical h e m i c o r d should be considered. References 1. 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